Not All Lithium–Indium\nCounter Electrodes Are\nMade Equal: Probing the Inhomogeneities and Kinetics of Uniaxially\nPressed Li–In Counter Electrodes in All Solid-State Batteries

Lithium indium alloys are commonly used as counter electrodes\nin\nall-solid-state batteries. However, the method of preparation varies\nfrom research groups, including ball milling, roll pressing, and uniaxial\npressing of the two metals. While the latter is a common approach\nused in the literature, it is not entirely clear how homogeneous uniaxially\npressed counter electrodes are and whether the differences can be\nobserved electrochemically. In this work, in the first section, two\ndistinct Li sources, one from the chemical Li–In alloy and\nthe other from the electrochemical Li–In alloy formed during\ncycling, are electrochemically probed and investigated as a function\nof the temperature, indium foil thickness, and Li area. In the second\nsection, the kinetics of electrochemically alloyed Li–In (e-Li<sub><i>x</i></sub>In) are investigated using Butler-Volmer\nkinetics to extrapolate exchange current densities in combination\nwith time and temperature-dependent distribution of relaxation time\n(DRT) analyses to better understand the alloying and dealloying process.\nThese findings underscore the considerable influence that counter\nelectrode preparation has on the kinetics and electrochemical performance\nof two electrode half-cells.