 Good evening to everyone and welcome to Faculty Colloquium, right, organized by, of course, our Faculty Colloquium team, Rasa Ratnakumar and Rasa Dilip and the whole team, and Office of the Alumni and Corporate Relations. So this is the second talk in the series concerning the recent works which were awarded the Nobel Prize and this time we requested Professor Sudhakar Chandran from our Department of Physics to enlighten us with his talk in the series concerning the recent works which were awarded the Nobel Prizes. The title of this talk, what Professor Sudhakar Chandran has decided is to Professor John B. Goodenough and the Lithium-Ion batteries. So as all of us know very well that the Lithium-Ion battery has is the advance is it's an advanced right battery technology that uses Lithium-Ion as a key component of its electrochemistry and Lithium-Ion batteries are capable of having a very high voltage and a charge storage per unit mass and a unit volume and as Professor Sudhakar Chandran has pointed out in his abstract that the Lithium-Ion batteries are ubiquitous as today we are using it everywhere every one of us hold it in one or the other electronic device we have with us. This was possible due to the tireless research and development and enabling technology where many have contributed in the last four to five decades and certainly Professor John B. Goodenough, Professor B. Stanley Wydingham and Professor Akira Yoshino their work has helped us to write use this battery for many many applications and for that they received the Nobel Prize in Chemistry in 2019. So Professor Sudhakar Chandran who is going to enlighten us in this regard in this work he is an associate professor at IIT Madras in our department of physics. Earlier he has worked in KTH that is Royal Institute of Technology Sweden and Wayne State University Detroit as a postdoctoral fellow and research assistant professor. His major research interests are in understanding the defect structure property correlations of multifunctional materials. The materials of interest includes oxides, calcogenides and nitrites and developing tailoring and engineering the material and its properties for the energy applications including lithium ion battery. Solar cells and multi ferroics are in his current research. So may I request Professor Sudhakar Chandran to write and deliver a talk which can write we will be very much very happy to hear you. Thank you very much for your time as well in preparation. Thank you Professor Vasan. I must thank the faculty association and the team for inviting me to present the work done by Professor John B. Goodenough and his contributions on lithium ion batteries. Last year Nobel Prize that is the 2019 Nobel Prize in Chemistry was awarded to three researchers. Professor John B. Goodenough is one among them. The other two are Professor Stanley Whittingam and Akira Yoshino. So all these three were given the Nobel Prize for their development for their contributions in developing the lithium ion batteries. So I will present in this talk the contribution mostly I will highlight the contribution is which John B. Goodenough did. So let me start with a brief introduction to Professor Goodenough. He was born in Gena, Germany of course an American citizen and he grew up mostly in New Haven, Connecticut. Initially he did his undergrads in maths at Yale. Then after after he served as an army captain during the World War II he went back to school in the University of Chicago where he found the intuition to pursue physics. After his graduation he spent almost one of the decades at the MIT Lincoln Laboratory as a research scientist and team leader mostly working on transition metal oxides for random access memory applications. And then he moved to Oxford University in 1976. There he led an inalwani chemistry group though he didn't have any chemistry background as such. In 1986 he went back of course in Oxford University only his prize winning work came out and he went back to the University of Texas Austin in 1986. He had received many metals and just to point out the one given by the president of the National Medal of Science. Of course he is the one of the oldest person to have ever won the Nobel Prize. So with that brief interaction let me get it let me summarize this he's basically a solid state physicist. He had contributed he had made outstanding contributions in solid state physics. His investigations on cooperative atomic orbital ordering in transit metal compounds has led to the realization of first random access memory. Of course from the work he did on transition metal oxides he formulated rules for sign of magnetic interactions in between transfer metal ions with the different d orbital configurations and different geometric configurations. So this is known as a good enough Kenamari rule. Mostly you will point this as a book material in magnetic magnetism topic. So just to give an idea about its super exchange interaction between two the super exchange interaction between transfer metal ions for example or anti-ferromagnetic when the virtual transfer between the overlapping orbitals takes place when the orbitals themselves are half filled. So this particular case I have I have shown is for 180 degree metal cation oxides and metal cation bonding angle. In fact such a such a prediction works even for bond angles between 120 degrees degree to 180 degrees. On the other hand if it is half filled or empty then these good enough Kenamari rules are very well known. It qualitatively tells about the materials whether it is anti-ferromagnetic or ferromagnetic and so on. It is extensively used by magnetic people who are doing magnetic research. Of course his other research include phase transition and phase segregation. He had extensively worked on inorganic solid state electrolytes. One of the well known Nazikon structure which is sodium in super superconductor conductors one of the compound he originally discovered and he has also worked on high-density superconductor. So with that interaction let me move on to the battery research. Before getting into what of course the pudding appeared I'll give a brief interaction to the battery. Of course the battery is it seems it is known it's not something new for us it is known well almost 2000 years old. So one of the by that the by that battery which has a terracotta jars with copper sheeting lay and iron rod instead it seems to be the oldest battery we have home. But the name battery itself was coined by Benjamin Franklin and so he mostly he was working on linked capacitors and then the animal electricity was shown by Galvani. That's most of the school works you will see it and the firstly electrochemical cell was designed by Volta. So since then you know many primary batteries primary batteries are basically one time use there is no you cannot reuse it again by charging it or so on. So many many batteries came out they got redesigned it evolves slowly zinc batteries and then such batteries came and then most of the well-known batteries are given in the table. So lead acid batteries and nickel cadmium, nickel metal hydride these are all rechargeable batteries which came but most of these batteries you know they have electrodes anode and cathode the cathode is positive electrode and anode is negative electrode and electrolyte filled in between them the electrolytes it's it is electronically it doesn't conduct charges but it connects the ions. So that's the structure of the battery. Lithium ion batteries came up by that I also highlighted here but I will tell about but you can see very contrast from difference the voltage of the lithium ion batteries are most two to three times more than any of the batteries known previously. Of course the very use of lithium in the lithium ion battery itself came because of the reason that it exhibits very high capacity and also gives very high discharge rate and this is possible because lithium is mostly electro positive the most electro positive element we have it's the very lightest one and therefore it facilitates the design of the storage system with high energy density. Okay so one of the one other important thing which came up was during 1960s and 70s is the intercalation compound which the Stanley Wittingham in fact I point the word it was crucial for the development of high energy rechargeable lithium ion batteries. So many compounds with intercalation intercalation compounds came up during that time so just to point out what it is for example a titanium disulfide it just is one of the example of intercalation compound in this compound you can shut you can insert and remove the lithium ion without the the structure undergoing any drastic changes. So these compounds are called intercalation compounds of course as you fill up lithium into into these host lattice they the conduction band gets filled up with the electrons as well. So with this as the cathode Stanley Wittingham first he he demonstrated the first rechargeable lithium ion battery when he was at Exxon Corporation and he used the titanium disulfide as the cathode and metal lithium as the anode and the electrolyte lithium perchlorate based on electrolyte. In this particular battery gave two volts of course the the charging cycle and discharging cycle curves are shown here I mean charging curves are shown here you can see that the voltage varies from the most like 1.5 to 2.5 volt. I think this will be the right time to give a little interaction on how your battery works. So here's a small video which shows how the battery functions so I took the lithium titanium disulfide as an example when when lithium is not there in titanium disulfide that is a charged state so with lithium inside titanium disulfide the battery is in a discharge state so so it moves from the discharge state to charge state and then it comes back when you as you discharge you can also see that as the lithium goes to the anode it gets filled up the the electrons get filled up and then the formula energy moves and the same thing happens on the other side as well. So the cell voltage is basically determined by the difference between the anox potential energies of the anode and cathode for example I have shown here PRE so this is the anox potential of the anode and cathode so this gives the net voltage. So in the case of titanium disulfide titanium the thermal energy is in the titanium 3d output house and 3d energy levels and then the formula energy of lithium is here so the voltage is you get. But then the voltage you get in titanium disulfide is 2.5 volt and and this is the largest voltage they could get with any of the sulfide as the cathode. Of course they just to point out the theoretical capacity it's basically how much charge you can store in the anode and cathode that's what it is. So that is given by this equation where n is the number of electrons power formula energy can put it in this case it is 1 because 1 in lithium goes in and out and f is a faraday constant and n is the molar weight of the materials. So of course you can define the energy density which is multiplied by voltage and then the power density and so on. So the one of the important thing with this particular cell design as Stanley Whitting and came up with it exhibited 2.5 volt which is very good the cycle ability was good but then it had a problems. So the shortcomings are that you know in this device when lithium goes back and forth it doesn't get uniformly coated every time instead it grows very uneven on the lithium surface and therefore dendrite like growths happen. So as one of the picture of microscopic picture is shown the dendrites grow and eventually they touch the cathode and they internally shots the battery. Therefore what happens is the battery catches fire and with the electrolytes which are which can easily catch fire you know it explodes and that was a problem and to some extent they try to mitigate this by using some alloy lithium aluminum alloy but then the cycle ability goes back. They were efforts to commercialize these batteries during the 1980s but then finally they had to drop because of these fire hazards. This is when first John Goodenough contribution came. So he being a solid state physicist he realized that he is basic understanding from his basic understanding for the three decades of working on transition metal oxides. He realized that the sulfur the maximum quality you can get from the sulfides is less than 2.5 that is because the sulfur 3P bands they lie much higher just below the lithium rods they lie at much higher. So the voltage is only 2.5 in the case of Titanium disulfide the Titanium bands which are just 0.2EB above us it gives about 2.3 volts or something 2.3 volts. So he realized that you know using oxides because oxygen 2B bands they lie at lower energy enables access to lower line energy bands and therefore one can achieve increased voltage output. So he realized that aspect and then he came up with a structurally similar company he explored the structurally similar compounds of LIMO2. So a Titanium disulfide has a close packing structure sulfur in and then the Titanium 6 in the octahedral sites they form a Van der Waal compound layer compound and in between these layers lithium goes in and out. So he found a similar compound in LIMO2. Of course the systematic studies was carried out in his group LIMO2 with a layer structure and there were very few compounds they could see for example Titanium was there but then the Titanium had very low voltage for the reason that the Titanium energy levels lie much closer to the lithium rods energies. On the other hand Vanadium, mananese and iron which could be prepared in the layer compound they always stabilize in the either structurally transform the spinel structure or they did not form good cathodes. Chromium compounds where they have very large polarization. Polarization means it is very difficult to put the charge in and out so it introduces a larger resistance to the charge transfer. So that was not possible and then nickel had a problem of oxidation it would always get reduced and then lithium goes away during the high synthesis and it was only compound they could find as the LICO2. It was like a magic compound so of course it came out of hard work they found that LICO2 they could reversibly extract half of a lithium in this compound. So it also gave a good cationic ordering basically the cationic ordering arises because lithium plus and cobalt 3 plus because of large difference in the charge and also the ionic radii they don't mix up between these layers. Lithium sits in an octahedral layer of its own and cobalt sits in its own octahedral layer. So the diffusion of lithium was much better in this compound. It had a very good basically it had a very good structural stability. It also exhibited very high electrical stability electrical conductivity so initially it had it exhibits a metal I mean the insulated character the moment you remove lithium it becomes a metallic so the metal insulated transition takes place in this compound and it happens because of the introduction of holes into the T2G6 bands. So they are very good connectors as you don't need to worry about how to extract the charges from these candles. So they had a good structural stability they had good electrical conductivity the ionic conductivity was good therefore fast charge and discharging characteristics was possible. In fact the lithium goes from one octahedral to other octahedral through the tetrahedral sides which lies in between and typical energy requirement is about 0.2 to 0.3 EV. So this was like a wonderful material that John good enough came up with and it solved two major problems. In good enough group they were looking for of course when he was working on an inorganic solid alloy compounds oxides compounds and then after the titanium disulfide were they were looking for two dual problem one problem is to replace the lithium with interglacial compound and the other one is to replace the cathode with a high voltage material. So this particular discovery enabled increasing operating voltage and the other problem is in the titanium disulfide like the battery the titanium disulfide doesn't have lithium to begin with whereas this compound has lithium to begin with which means when you assemble the battery this compound is in discharge state whereas the titanium disulfide is in a charged state the battery you made using titanium disulfide cathodes are in charged state which means you know it gives a lot of engineering related problems to assemble the batteries. So this particular compound was very useful of course until Akira Ayoshino came up with a suitable anode the birth the birth of lithium ion battery was not realized so he used some carbon based material which also had a layered structure and lithium can easily interglade between the layers and so that gave a lithium free anode the graphitic anode which was suitable for a lithium cobalt oxide as cathode to begin with. Therefore the batteries could be assembled and Akira Ayoshino showed that if you made the battery using lithium metal where lithium metal has the anode if you have the batteries you made they catch fire very easily whereas the lithium ion batteries made with the graphene does not catch fire and this instant is considered as the birth of lithium ion batteries of course a Sony company went on to make the first commercial batteries using this material there is a there was a this is not something again completely you know acceptable compound for the reason that the lithium you could extract from this compound LiCO2 is only half so you you cannot remove the other half the reason is that the cobalt redox the cobalt energy levels you know they they overlap with the oxygen 2B bands and therefore what happens if you try to extract more than half the lithium you also tend to remove the electrons from the 2B bands which makes the oxygen to escape from the lattice and therefore the structure collapses. So despite its wonderful cathode properties it would not be used to its fullest capacity and the problems that exist till today there is no compound you can get where you can you can get one lithium equivalent you can extract one lithium from from the formula unit. So before moving into the contributions other contributions you made I will just make a point here of course the lithium cobalt oxide as they all go over years into one of the compound that is most well known is the NMC compound in this compound the cobalt is replaced substituted with nickel and manganese in equal proportions of course there are many different compositions I will show in the next slide. So this particular compound is very special for the reason that the in presence of manganese manganese nickel always tries to stay in the 2 plus state because of the energy levels so it reduces the nickel manganese gets oxidized and and therefore the chemical stability for manganese is much better than this and most of the lithium redox happens between the nickel and cobalt compound and this particular one give much better capacity up to 160 milli ampere hour per gram and there are many such compounds that are being explored even today just to point out the the complexity that is involved in deciding the right composition you can see in this phase diagram some of the important compounds that are known are highlighted they are given names based on the ratio of the nickel to manganese to cobalt for example 424 means 40 percent nickel and 20 percent manganese and 40 percent cobalt like that so there are many many different composition is explored but then what happens if you try to increase the discharge capacity then the thermal stability decreases and also the capacity retention decreases but then we we want the preferred performance to be somewhere there so there is always a given take that happens so a lot of studies still going on to find out the suitable material which can give very high capacity and also can retain the capacity over large number of cycles in the batteries so with that let me move on to the second class of oxide materials which came up from Prasagudinath group Mike Thakri he was a researcher from South Africa he realized he showed that lithium can be inserted reversely in a 534 structure it's basically the magnetic material you all know as a low stone and till then it was realized that you need to have a layer structure in order to insert the lithium very smoothly in between the layers but then he showed that 534 which has a spinel structure where the octahedral connected in all directions he showed that it is possible to reversibly intercalate the lithium so he came to Prasagudinath group and then with Prasagudinath together they came up with a second material that's our second wonderful material Li MN2O4 it's a spinel composition the lithium sits in the A sites that is the ATI position the white off positions and then the manganese sits at the 16B position and oxygen forms a close packing again cubic close packing so this particular compound the lithium again diffuses from octahedral the tetrahedral sites it sits in the tetrahedral site so one tetrahedral site to other tetrahedral site through the 16C sites here so the direct manganese-manganese interaction across the MNO6 of the hetra edges and also the mixed valent high-spin state it enables the good hopping electronic conduction in these compounds of course the conductivity unlike in Li-C002 it is the conduction in this case is through the small polar arms and it's a small polar arm hopping conductor so this particular compound has a very good structural stability and therefore it enables fast charge discharge characteristics it also has a voltage 4 volt and in this compound lithium one if you try to remove one lithium you can get 130 milliampere hour program so this is another wonderful material they came up with of course this is patented in South Africa which a good enough gracefully agreed for that so in this particular compound you question that you can also insert second lithium in Li-MN2O4 spinel you can put one mode lithium and they showed it is possible therefore the capacity would be increased to 270 milliampere hour program beautiful science came out of this thing in fact the moment we were trying to put second lithium the voltage which was at 4 decreases to close to 2.83 so this the reason for this is the lithium which was initially at 8A position now it it moves to 16C position and there is an associated distortion in the structure but the distortion comes because of the antler effect the manganese in 4 plus when it becomes manganese 3 plus you know there's a electrostatic collision between the oxygen 2P non-bonding orbitals and then the D orbitals which leads to the distortion of the upper head wrap and that makes the cubic spinel structure undergo tetrahedral spinel structure so this particular in fact in the very first first charging a discharging cycle also you can see two steps and that is associated with the redistribution of lithium ions so this particular structure told many things there is a side dependent voltage that a material can give for example in this in this region it gives around 4 volt there itself you have two different two different kinds of lithium distribution and therefore the voltage slightly changes and the other one if you try to put the second lithium the voltage is totally different this but second lithium insertion could not be utilized for practical applications for the reason that it undergoes tetrahedral spinel structure which has a huge structural distortion and therefore the material becomes you know pulverizes so you cannot do it you cannot practically utilize the extra specific capacity in stroke so that still remains the challenge till today so in the other advantage of LIMN204 over cobalt is it's very cheap the cobalt is becoming very very costly and it is also toxic so manganese is going to be the better option for cobalt but then there are other issues with this compound the manganese kind of easily dissolves in the electrical line it undergoes a disproportionation reaction manganese 3 plus would become 2 plus and 4 plus and 4 plus will get retains in the solid and 2 plus gets leached out in the solution because of the the electrical line and also these 2 plus get shuttled to the anode and where it gets coated and therefore you have a limited cycle line so there are many issues and of course like LIM O2 structure many other many other spinel compounds were explored titanium has a spinel oxide but then again its voltage is very less because of the titanium DD levels where it position itself in the band structure vanadium it undergoes structural change the cobalt nickel oxide they cannot they are very unstable in the higher oxidation state therefore the only compound that could stay structurally stable is LIMN204 there were other compounds people so they substituted two different material two different elements and prime one of the compound very promising is the if you substitute 0.5 nickel in the in the place of manganese that is LIMN1.5NA0.504 this operates at much higher voltage than the and the LIMN2 around 4.71 over the capacitor which means you know you can increase the energy density but then the problem is you don't have a suitable electrolyte the electrolyte will undergo redox reactions if you if you go beyond certain voltage so there are issues with that too so yeah with that second compound which came up from of course it would be enough to work like we move on to the third class of oxides so the compound I mentioned that he came up with the non-lionics holiday electrolytes the nazikon based one that was a original contribution from good enough as this he was working on several oxides as well as I mentioned and they professor Arvogam Manthiran who was a who graduated from IIT Madras then he joined professor good enough's groups as a postdoc so so they wanted to explore some of these poly anionic compounds so you don't have oxygen as an anion here you have an MO04 as an anion so it's it's the that's why it's a poly anion and Manthiran found out that when he studied FE2, WO04 and moly poly anion he found that the voltage around 3.3 volts which is much higher than the ion also itself would give so becoming curious they also explored sulphate poly anionic compounds so these are all the these all exhibit the nazikon structure and they found that the exhibit 3.6 volt so the voltage could be increased by changing the poly anion time so here picture really is shown FE2 O3 has a less than 2.5 volts the moment you put moly or tan stand it is 3 volt sulphate it's 3.6 and they explained this based on the inductive effect so in this particular nazikon structure the iron oxygen the moly oxygen ion they they are connected well because of the structural connection they have and the for example the moly oxygen bonding is very covalent a highly covalent and that weakens the covalent character of the covalency of the FE4 in other words the electron negatively changes if you change the poly anions so as the electronegativity increases it pushes the FE2 plus FE3 plus redox energy level down which results in increasing the cell voltage so with again with a large number of experiments these these ones although it could it could exhibit 3.6 volts it could not be used because of the energy and the capacity is very less because it has two extra sulphate more number of sulphate which is inactive isn't it so they came up with this li fep4 compound and that was another wonderful material the padi is the one who did this in in good enough research good enough research land so in this particular compound the lithium moves in and out in a one-dimensional fashion so there are tunnels the tunnels are running along the V axis and it moves in and out through the these tunnels of course it doesn't go straight people have shown theoretically that the the position it takes it goes in a kind of a baby in a baby pattern through the channels and this particular compound there are the li mn p04 also was prepared and it was shown to have much higher voltage than li fep4 but the capacity is more or less equal so this particular electron by playing with the electronegativity of the anion one can change the voltage what's shown in this particular valentine compounds of course there was some confusion here with ion being more electronegative exhibits very less voltage compared to manganese because as you go from the left side to the right side in the transition metal row ion would be more electronegative but then they found that this exhibits lower voltage and they found it is in fact the redox energy levels get shifted due to the panning energy so the sixth electron which which gets occupied here it controls the the energy level so what controls the voltage in these compounds were thoroughly investigated by good enough groups and of course many different anionic compounds were investigated since then and these two lines here show the 600 watt hour per kg specific energy density and typically they wanted something more than 600 then so iron and manganese want to be the suitable materials of course cobalt and nickel versions also were shown but then they could not be used because it is beyond the potential where you can safely operate the lithium ion battery anything beyond this you know electrolyte would go undergo reduction of oscillation reaction so came three different materials from first a good enough group they had very different characteristics in terms of the dimensionality of the lithium ion transport you can see that the in LIFE PO4 the polyion ion compounds lithium moves in and out in a one-dimensional fashion the layered compound has a two-dimensional lithium diffusion whereas the spinel LIMN204 has a three-dimensional diffusion so to find to summarize the key findings which Professor good enough did from his fundamental understanding on transition metal oxide the properties he explored he came up with he identified three different compounds three classes of material till today there are no other cathode materials than these three most of the cathode materials are based on these the structurally they are similar layered oxides spinel oxides and poly anion oxides are generally they are required by so he pushed the boundaries at the intersection of solid state chemistry and physics he being the solid state physicist in this particular picture the three compounds are shown in addition there are two other compounds the NMC NMC is shown which came from it is a improved version of LICO2 layered compound the manganese 1.5 nickel 1.5 spinel is another improved version of the spinel compound that came up with so nowadays people are looking at lithium rich layered oxide which is slightly modified based on the layered oxide so they show close to ability to show close to 250 or more than 250 milli ampere hour per gram but then there are issues with cyclability and so on so current research is mainly people are carrying out to how to mitigate those losses okay so with that interaction with that detail on of course the good enough to research work let me point out some of the things if he so most of the most of these compounds whatever the compounds layered layered oxides poly anions or spinel compounds they are used in applications which involves mobile ITs basically mobile phones charge charging batteries or power tools and they are also used in electric wake holes but then one has to understand the requirements of energy are very wide there are about eight orders of difference in the energy requirements for example if you want batteries for watches and calculators it's only few and whatever whereas mobile phones require a few tens of whatever and then this goes up the moment you come for electric vehicles you need something of 10 to the power six so it's in the order of a few hundred kilowatt hour and also for great applications you need much higher so can the batteries serve this purpose is a big percent for example the tesla model and the electric vehicle which tesla has come up but you can see how it compares with the regular cars the battery pack itself takes a huge weight it is 40 540 kilograms compared to 40 kilograms for the engine one so unless the the energy density is improved almost twice it's going to be tough to get the you know viable batteries for electric vehicles of course there are a lot of other compounds are coming up you one also has to in addition to increasing the capacity one also has to improve the power density the power density is basically how fast you can draw that charges and if you try to draw a charges much faster then the voltage goes down the capacity that you can get it also goes down so looking at the battery technology landscape it doesn't scale up with Moore's law for electronics it doesn't go that way even with an aggressive projection what has been shown is in the next 30 years if the capacity energy density goes by two times that itself will be big achievement and then the the way it can be done people are projecting you know lithium-ad is the lithium-ad batteries are the way they again it's a slightly different than what the the batteries are explained based on the cathode and anode oxides of course there are various ways people are trying to explore making the batteries suitable safe and cost effective if you want to if you want to make it safe then the cost goes high and therefore one other area where people are seeing that the batteries would serve is the solid state batteries you have to remove the lithium remove the liquid electrolyte in the battery and make it solid electrolytes and that is one of the hot topic currently going on so yeah so in the in the years to go lithium-ad batteries are projected of course a lot of research on the cathode as well as on the anode side is carried out I didn't touch upon the anode research in this and so with with the possible suitable anode and cathode and probably electrolyte solid electrolyte is possible that one can get much better batteries so we need to wait and see with that of course these these are the what I show is not the one lithium person putting us to its desk he works on lithium sulfur batteries lithium batteries lithium or lithium oxide batteries sodium ion potassium and batteries both positive and negative of course a lot of things his group explores one of the things they recently came up with is a glass battery which is basically there's all solid state battery we have used electrolyte which is glassy in nature and show that the battery the performance they can get from this compound this particular electrolyte is three times better than what they have shown but of course there was a lot of controversy related to that but seems that there are a lot of research going on to to make it possible commercially viable so with that I will stop so first John good enough has contributed in a way that has changed every human how they are they are using their using the electronic devices nowadays of course I will not be surprised if somebody holds a mobile phone and sits in a terrace or in a tree who are very far from the city to catch up this talk so without draining the battery much so I thank you all for your attention if you have any questions otherwise you know in case if I'm not able to reach you or some thing you can always email me and let me stop here thank you very much for your attention oh I need to go with snow yes thank you so much because it's very very nice talk we learned so many things and now now please if a few questions we have a little time for a few questions and of course afterwards through email also it should be possible however a few questions if anyone would like to hi Sudhakar hello can you please explain what is this glass about the lithium and lithium glass battery what is the glass here the glass is state of lithium or no this is the electrical line actually so this is an electrical line where the lithium conduction so the batteries I explained it has a literary back of life means you know the lithium salt is dissolved in organic solids whereas this is a solid material it has a very high lithium ionic conductivity and of course there was I I don't know exactly the nature but what what they showed is they they had a lithium on either side of this glass battery and then they showed that it exhibited high voltage and there was a lot of controversy because you need to have a difference in foamy energy between the anode and cathode to extract voltage but this particular work which appeared in jacks they showed in despite using lithium on either side for this particular glass glassy electrolyte they showed a wonderful performance and and of course right now a lot of the interface what happens exactly at the interface in these particular batteries are being explored okay thank you thank you for the nice lecture also thank you okay can I ask a question yes hello this is Rangara from chemistry department hello sir yeah yeah nice yeah very nice I am so happy to listen to you thank you I have one small question that you mentioned about dry polymers solid state lithium ion batteries yeah yeah dry poly here yes the electrolytes that that's that are being investigated is it but they will have an exchange like you know like you know like normal how do they how do they exchange ions um so I don't know the exact polymer nature what they use but then these lithium ions are basically immobilized in these polymers and they can move around actually so that's what they oh I see lithium ions are lithium ions are embedded in the polymer yes they move around so the the the medium is solid that's right the polymer itself is solid but the lithium ions can easily move through these polymers okay so if that is successful I don't know whether it is successful or not that is successful that can be applied to many many other devices also that's true yeah I don't know I'm not a polymer person but I'm sure there are a lot of work on that direction as well yes it's it's completely multi-disciplinary stuff this particular battery stuff I see I'm because I yeah yeah because I heard that you know the Chinese are trying that Germans are trying that which could be polymer or oxide based one and this also this this will make the the electrochemical window larger so that you can use a high voltage cathode for the purpose number one and also the solid uh electrolytes they prevent the lithium growing from one side to other side the dendrite growth and all can be mitigated so the shard the shards are shooting the shard sharding doesn't happen the battery explosion and all this doesn't happen that's how that's the advantage of the solid can be stopped yeah but it is operated at the same temperature difference is something one has to explore as well because it changes from the model in certain components they could vary so when the batteries are made there are set up for things one need to in terms of performance evaluation one people have to for example here if the thermal management if too much of heat is produced you have to have thermal management system in order to make that battery work so yeah a lot of components get added up to tackle the problems that comes out of the battery battery other issues yeah last question sorry I've been taking too much of time instead of lithium because lithium is now going to be you know very difficult to get it's only available in chili it's only available in chili i think most of it uh can it not be replaced with any other sodium ion batteries are being explored sodium ion potassium ion batteries uh some of the predictions also say for example you can see the future here sodium ion also has a future battery for this reason okay yeah so they okay so if that is successful in sodium uh and show that the sodium ion intercalation is also possible but a lot of research work needs to be done I think before the reality can work up workable batteries okay so that is that is very interesting thank you so much yeah thank you sir thank you can I ask you a question yeah please you mentioned about earlier that titanium disulfide has a cathode right yes it doesn't have a lithium right so was there any problem in starting or something like so the problem I mentioned with the titanium titanium disulfide right um let me go yeah so here what is the question I'm sorry I think you mentioned there is some problem in starting or something right because of the absence of lithium so what happens is in titanium disulfide so let me we go here yeah so here when the when the lithium is in the titanium disulfide okay so basically the the lithium shattles between the anode and cathode but when it is in titanium disulfide the battery is in a discharge state okay so whereas when the when the lithium sorry when the lithium is in between the titanium disulfide and discharge state when it is in the anode it is empty then it is a charge state so when you fabricate the battery using titanium disulfide as a cathode and anode whatever the anode it is already in the charge state basically so if you try to assemble them uh it would get discharged and sparking all these engineering problems are there that's what I mentioned whereas with lac o2 you have a cathode with lithium intercalated in it because you cannot produce li tis to basically to begin with whereas lac o2 you can prepare so you can synthesize them so uh due to this you know you can assemble the batteries in a discharge state that's what I mentioned all right thank you yeah thank you hi hi to that Siddhartha Chandran this is uh Indu Pandit Tiwari uh I'm working I'm sorry yeah this is the Indu Pandit Tiwari yeah I'm yeah I'm from USA right now so I have one question uh in this lithium glass battery uh this glass is polymer of fiber uh what is the action of this glass means it is work as a cathode or it is work as an anode in it is an electrolyte so the one I mentioned on the last time is it yeah please please continue yeah so basically uh oxide uh something like you know nazikon inorganic solid electrolyte oxide based one it is something of that sort even I'm not sure exactly what is the what is the chemistry and how the voltage is coming and so on so but what it is is it's basically a glassy glassy means you know there is no structural order ordered it is it's kind of a disordered system oxide system but then it has a high mobility high high mobility for the lithium lithium can easily move around um I think the conductivity lithium ion conductivity is 10 power minus 2 10 power minus 3 c even per centimeter if I remember and so they use this as an electrolyte it's not an anode but then they use in the work they of course are good enough work maybe you can you can look for this particular thing I think braga is vr a ga braga is a person another researcher who is the first author in this work they have used a lithium on either side of this electrolyte and surprisingly it shows a very high voltage there were a lot of criticism on this and so of course there was a news about you know at the age of 97 years you know personal good enough has again done it something like when he did l.a. c o water he was 57 and after 40 years you know almost at the age of 97 he again made a big change in the battery the very part something of that sort no news came and but it looks like they are perceiving it to really understand what is happening and great thank you yeah thank you very much if if there are no more questions of course we can write and email to sudhakar's and get some right input as well whenever afterwards you have some time however professor sudhakar how about our progress this similar research and the corresponding manufacturing aspects of this in India related to lithium ion between secondary by any chance there are many unfortunately I think we don't have any for example the the components liquid anode and cathode you know you have to produce them in in tons and tons to make larger number of batteries I think we don't have that facility and there are there are efforts to put such plans for materials synthesis as well as battery production in a large large numbers even to produce something of 100 kilowatt hour I think there are no no facilities government based one I am not sure about the even the private parties as well most of the thing what they do is they buy the small batteries and assemble them together yeah yeah which is going to work out on along yes we have to do the batteries here ourselves and that is something challenging and yeah okay understood sir so if no more questions then let us thank professor Sudhakar Chandran for this very very thank you so much very right very much inside starting with basics introduction and then bringing us to the point where we start thinking about applying right at the same time materials and its progress so nicely thank you so much thank you very much input we are extremely sorry for not keeping memento ready but it will be it will be delivered to your please and yeah thank you so much thank you so much right yeah right with this please take over yes yes yes yeah I would also like to thank professor Sudhakar Chandran for accepting our invitation and delivering the talk despite he was busy with the departmental work recently but thank you very much Sudhakar and thank you everyone for joining us today thanks for arranging this talk in fact it was it was good I also learned a lot during this preparation yeah okay hi everyone so thank you thank you professor Rakhna Kumar, professor Dilip everyone for all right continuous arrangements and everything so nice of you sir yeah it's our pleasure thank you