 highlights mechanistic understanding of ion transport phenomena in composite solid-state electrolytes, CSEs, for practical solid-state batteries is conducted. Percolation threshold formation of the inorganic LPSCl phase in the CSEs depends on elasticity of the gel polymer electrolyte, GPE, phase. Manipulating the salvation slash desolvation behavior of the GPE phase facilitates ion conduction across the LPSClGPE interfaces. This article was authored by Kion Suk-ho, Ji-yoon Lee, Yong-hyeok Lee, and others.