Coupled with anionic and cationic redox chemistry,Li-rich/excess cathode materials are prospective high-energy-density candidates for the next-generation Li-ion batteries.However,irreversible lattice oxygen loss would...Coupled with anionic and cationic redox chemistry,Li-rich/excess cathode materials are prospective high-energy-density candidates for the next-generation Li-ion batteries.However,irreversible lattice oxygen loss would exacerbate irreversible transition metal migration,resulting in a drastic voltage decay and capacity degeneration.Herein,a metastable layered Li-excess cathode material,T2-type Li_(0.72)[Li_(0.12)Ni_(0.36)Mn_(0.52)]O_(2),was developed,in which both oxygen stacking arrangement and Li coordination environment fundamentally differ from that in conventional O3-type layered structures.By means of the reversible Li migration processes and structural evolutions,not only can voltage decay be effectively restrained,but also excellent capacity retention can be achieved upon long-term cycling.Moreover,irreversible/reversible anionic/cationic redox activities have been well assigned and quantified by various in/ex-situ spectroscopic techniques,further clarifying the charge compensation mechanism associated with(de)lithiation.These findings of the novel T2 structure with the enhanced anionic redox stability will provide a new scope for the development of high-energy-density Li-rich cathode materials.展开更多
基金supported by the National Science Foundation under Grant No.DMR1809372。
文摘Coupled with anionic and cationic redox chemistry,Li-rich/excess cathode materials are prospective high-energy-density candidates for the next-generation Li-ion batteries.However,irreversible lattice oxygen loss would exacerbate irreversible transition metal migration,resulting in a drastic voltage decay and capacity degeneration.Herein,a metastable layered Li-excess cathode material,T2-type Li_(0.72)[Li_(0.12)Ni_(0.36)Mn_(0.52)]O_(2),was developed,in which both oxygen stacking arrangement and Li coordination environment fundamentally differ from that in conventional O3-type layered structures.By means of the reversible Li migration processes and structural evolutions,not only can voltage decay be effectively restrained,but also excellent capacity retention can be achieved upon long-term cycling.Moreover,irreversible/reversible anionic/cationic redox activities have been well assigned and quantified by various in/ex-situ spectroscopic techniques,further clarifying the charge compensation mechanism associated with(de)lithiation.These findings of the novel T2 structure with the enhanced anionic redox stability will provide a new scope for the development of high-energy-density Li-rich cathode materials.
