Multi-functionalized full-interface integrated engineering towards highly reversible Li-rich Mn-based cathode

Li-rich Mn-based materials (LRMs) with high energy density are promising cathode candidates for next-generation lithium-ion batteries. However, the inevitable oxygen release and electrolyte decomposition would stimulate successive interface side reactions and structure degradation, leading to rapid capacity decay. In addition, the terrible reaction kinetics of LRMs is not conducive to rate capability and low-temperature performance. Herein, a multi-functionalized full-interface integrated engineering is put forward to introduce multifunctional modification layer (including surface S, N co-doped carbon layer, near-surface gradient oxygen vacancies and the resultantly induced atomic rearrangement) at the interface of both the secondary particles and inner primary particles of LRMs. The oxygen vacancies and induced intralayer Li/Mn disorder can suppress the oxygen release. And the induced lattice-matched rock-salt phase can improve the interface structure stability. Meanwhile, the S, N co-doped carbon layer can isolate LRMs and electrolyte, alleviating the decomposition of electrolyte and the resulting structural damage to LRMs. In addition, Li+ diffusion kinetic and electric conductivity are enhanced due to oxygen vacancies and S, N co-doped carbon layer. Thus, a reliable LiF-rich cathode electrolyte interphase (CEI) film is formed, which can further reduce the interfacial side reactions upon cycling, ultimately enhancing the comprehensive electrochemical performance of LRMs. Specifically, the modified sample (HLRM) exhibits enhanced long-term cycle stability, with capacity retention of 94.8 % and 86.6 % after 100 cycles at 0.2 C and 500 cycles at 1 C, respectively. In addition, HLRM delivers elevated specific capacity and cyclic stability both at high (55 °C) and low (−15 °C) temperature. This work offers a new idea to improve the comprehensive electrochemical performance of LRMs by multi-functionalized full-interface integrated modification engineering.