Constructing Uniform and Robust Li₃N Interface by Methacrylamide Additive Achieves High Performance of LiNi_0.5Mn_1.5O₄ Battery

Because the traditional electrolyte is unstable at high voltage, the commercial use of LiNi_0.5Mn_1.5O₄ in power batteries still faces huge challenges. Regarding this, the introduction of additives directly into the electrolyte is one of the easiest ways. Herein, an amide compound, methacrylamide (MAA), is proposed as a novel additive into the conventional electrolyte in our work. The amino group (-NH₂) in MAA can undergo coordination and complexation reaction with strong lewis acid PF₅. Additionally, MAA can be preferentially oxidized to stabilize the electrolyte and decomposed to generate nitrogen-containing (Li₃N) interface components with high ionic conductivity. Therefore, the Li/LiNi_0.5Mn_1.5O₄ battery with 0.5 wt % MAA electrolyte delivers an initial specific discharge capacity of 141.7 mAh·g^-1 and maintaining an outstanding capacity retention rate (95.2%) and a very high average Coulombic efficiency (99.1%) after 200 cycles at 0.2C. MAA provides a new idea for broadening the application of carbonate electrolytes under a high voltage.