Enhanced electrochemical performance of lithia/Li2RuO3 cathode by adding tris(trimethylsilyl)borate as electrolyte additive

Abstract

In this study, we used tris(trimethylsilyl)borate (TMSB) as an electrolyte additive and analysed its effect on the electrochemical performance of lithia-based (Lithia/Li2RuO3) cathodes. Our investigation revealed that the addition of TMSB modified the interfacial reactions between a lithia-based cathode and an electrolyte composed of the carbonate solvents and the LiPF6 salt. The decomposition of the LiPF6 salt and the formation of Li2CO3 and -CO2 was successfully reduced through the use of TMSB as an electrolyte additive. It is inferred that the protective layer derived from the TMSB suppressed the undesirable side reaction associated with the electrolyte and superoxides (O- or O0.5-) formed in the cathode structure during the charging process. This led to the reduction of superoxide loss through side reactions, which contributed to the increased available capacity of the Lithia/Li2RuO3 cathode with the addition of TMSB. The suppression of undesirable side reactions also decreased the thickness of the interfacial layer, reducing the impedance value of the cells and stabilising the cyclic performance of the lithia-based cathode. This confirmed that the addition of TMSB was an effective approach for the improvement of the electrochemical performance of cells containing lithia-based cathodes.