Investigation on the interface between Li10GeP2S12 electrolyte and carbon conductive agents in all-solid-state lithium battery

Abstract

All-solid-state batteries are considered as one of the attractive alternatives to conventional lithium-ion batteries, due to their intrinsic safe properties benefiting from the use of non-flammable solid electrolytes in ASSBs. However, one of the issues in employing the solid-state electrolyte is the sluggish ion transport kinetics arising from the chemical and physical instability of the interfaces among solid components including electrode material, electrolyte and additive agents. In this work, we investigate the stability of the interface between carbon conductive agents and Li10GeP2S12 in a composite cathode and its effect on the electrochemical performance of ASSBs. It is found that the inclusion of various carbon conductive agents in composite cathode leads to inferior kinetic performance of the cathode despite expectedly enhanced electrical conductivity of the composite. We observe that the poor kinetic performance is attributed to a large interfacial impedance which is gradually developed upon the inclusions of the various carbon conductive agents regardless of their physical differences. The analysis through X-ray Photoelectron Spectroscopy suggests that the carbon additives in the composite cathode stimulate the electrochemical decomposition of LGPS electrolyte degrading its surface during cycling, indicating the large interfacial resistance stems from the undesirable decomposition of the electrolyte at the interface.

Interfaces Between Cathode and Electrolyte in Solid State Lithium Batteries: Challenges and Perspectives

“…The research demonstrates that suitable conductive additive and sulfide solid electrolyte are crucial to overcome the poor cycle performance of high-voltage solid state lithium batteries. Yoon et al (2018) also investigated the interface between Li 10 GeP 2 S 12 and diverse carbon conductive agents in solid state lithium batteries and confirmed the solid electrolyte decomposition and surface degradation during cycle.…”

Computational Screening of Cathode Coatings for Solid-State Batteries

“…As a result, thiophosphate decomposition is unavoidable when using a strategy of only coating the cathode, and degradation at these interfaces will form ionically insulating ''dead space'' in electrolyte particles. 25,27 In principle, because neither electron transfer nor Li-ion transfer is required at these interfaces, the decomposition of thiophosphates should not immediately affect the low-rate cell performance. However, ''dead space'' will negatively affect the ionic conductivity of thiophosphate particles and therefore increase the internal resistance of the cell.…”

Electrolyte and Interface Engineering for Solid-State Sodium Batteries

“…In addition, recent studies reveal that the conductive carbon additives could stimulate the electrochemical decomposition of sulfide-based SSE (Li 10 GeP 2 S 12 ) in all-solid-state lithium batteries during cycling processes, leading to large interfacial resistance and capacity fading. 81,82 It is meaningful to investigate whether the conductive carbon would affect the electrochemical stability and interface of sulfide-based SSE in sodium batteries.…”