A Multifunctional Additive Capable of Electrolyte Stabilization and Structure/Interphases Regulation of High-Energy Li-Ion Batteries

Ni-rich cathodes are regarded as the most suitable candidates for high-energy-density Li-ion batteries (LIBs). However, the structural degradation of Ni-rich cathodes and high reactivity of electrolytes at the high-potential cathodes greatly affect the cycling stability. One of the prime reasons is that HF produced by the thermal decomposition and hydrolysis of the electrolyte salt LiPF6 can cause corrosion at the electrode/electrolyte interface, promote the transition-metal dissolution from cathode, and aggravate the decomposition of the electrolyte. This work develops a multifunctional and promising silane-based electrolyte additive, vinyltrimethylsilane (VTMS), which is generally applicable to Ni-rich cathode-based LIBs. Theoretical calculations and practical experiments reveal that VTMS is capable of eliminating HF, stabilizing PF5, and suppressing the hydrolysis of LiPF6. Besides, the additive VTMS undergoes redox reactions prior to other electrolyte components, mitigates the electrolyte decomposition, and constructs superior interphases at both cathode and anode. The electrochemical performance of LIBs is significantly improved at both room temperature (25 degrees C) and low temperature (0 degrees C), demonstrating that VTMS has broad application prospects in LIBs. The development of such a multifunctional additive is of great importance for simplifying the electrolyte composition. A multifunctional additive capable of eliminating HF, mitigating electrolyte decomposition, constructing superior interphases at both cathodes and anodes and stabilizing the crystalline structure of Ni-rich cathodes is developed. This additive is generally applicable to Ni-rich cathode-based Li-ion batteries and greatly improves their electrochemical performance. image