Boosting the comprehensive performance for a Co-free high-voltage system with a multi-component nitrile

Abstract

Lithium-ion batteries with high-energy density are a hot spot in current research, and the 5 V class of high-voltage LiNi_0.5Mn_1.5O₄ (LNMO) cathode materials attracts widespread attention because of its high specific capacity. However, the traditional electrolyte causes unnecessary reactions with the LNMO interface at high voltage, so choosing a suitable electrolyte is key to the development of the above-mentioned battery system. Here, we introduce 1,3,6-hexanetrinitrile (HTN) as the high-voltage additive to improve the oxidation stability of LNMO/Li cells. Compared with the conventional nitrile-based additive adiponitrile (ADN), the HTN additive can provide more nitrile functional groups to reduce the problem of decreased electrolyte viscosity caused by adding too much ADN. Besides, in order to improve the suboptimal performance of HTN in the mesocarbon microbead (MCMB) anode, methyl benzenesulfonate (MBS) MBS with characteristics of a protecting lithium metal anode at low potential is compounded in the electrolyte to improve the performance of LNMO/MCMB batteries. The synergy and complementary advantages of HTN and MBS improve the overall performance of the LNMO/MCMB battery system. Modification of commercial electrolyte systems with compound additives as required becomes a major direction for the future design of electrolyte formulation.