Characterization of Limiting Factors in All-Solid-State Lithium Batteries Using an Embedded Reference Electrode

Abstract

Three-electrode system has been universally utilized in lithium ion batteries to understand the reaction mechanism of working electrodes during charge-discharge process. However, it cannot be readily applied in all-solid-sate batteries (ASSBs) due to the practical constraints to the selection and placement of reference electrode in solid electrolyte. Herein, we investigated factors influencing capacity fade in ASSBs consisting of Li2S-P2S5 solid electrolyte, Li4.4Si anode and TiS2 cathode, with embedded reference (In) electrode. Ohmic resistance (R0), charge transfer resistance (Rct) and polarization resistance (Rp) were determined for each electrode, using three electrode setup. The first discharge process was dominated by the low lithium diffusion coefficient in TiS2. The first charge capacity was significantly reduced due to sluggish kinetics of alloying process, which sequentially affected the next cycle performance. The results indicate that alloying process is a critical step to determine the performance of ASSBs consisting of alloy electrode.