Characterization of limiting factors of an all-solid-state Li-ion battery using an embedded indium reference electrode

Three-electrode system is universally utilized in lithium-ion batteries to study the reaction mechanism of working electrodes during the charge-discharge process. In all-solid-sate batteries, however, it cannot be easily used due to the practical constraints to the selection and placement of the reference electrode. We investigate the factors that influence capacity fade in all-solid-sate batteries consisting of Li2S-P2S5 electrolyte, Li4.4Si anode, and TiS2 cathode, with an embedded reference electrode. Ohmic resistance, charge transfer resistance, and polarization resistance are determined for each electrode using the embedded probe. The first discharge process is dominated by a low chemical diffusion coefficient of TiS2. The first charge capacity is reduced due to the relatively sluggish kinetics of the alloying process, which sequentially affects the next cycle performance. Diagnosis using the three-electrode setup reveals that the alloying process is a critical step in determining the performance of all-solid-sate batteries with alloy electrodes.