Preparation And Modification Of Ultra-high Nickel LiNi_0.9Mn_0.1O₂ Cathode Material

Ultra-high nickel layered oxide cathode material with high energy density is the most promising material to improve the electrochemical performance of lithium-ion batteries（LIBs）.However,due to the scarce,expensive and environmentally unfriendly cobalt resources,it is of great practical importance to develop ultra-high nickel cobalt-low or ultra-high nickel cobalt-free layered oxides.Moreover,the poor structural stability and severe surface/interface side reactions of the material lead to poor rate performance and cyclic stability,which limits its application in practice.Therefore,it is indeed a great challenge to significantly reduce the cobalt content or remove cobalt in ultra-high nickel layered oxide cathode materials while maintaining excellent electrochemical performance at the same time.In this paper,Li Ni_0.9Mn_0.1O₂（NM90）cathode material is modified by La₂O₃ coating,and La³⁺doping caused by thermal diffusion is achieved simultaneously.The synergistic enhancement of the two modifications can effectively improve the layered structure and reduce surface/interface side reactions.The dual-modified material shows good structural stability,the La₂O₃ coating does not fall off and the active material does not appear fragmentation and collapse after 100 cycles.At the same time,the dual-modified material also shows excellent electrochemical performance,with a capacity retention of 83.2%after 100 cycles at 1 C and a reversible capacity of 129.9 m Ah g^-1 at 10 C.The electrochemical mechanism reveals that the dual-modified material effectively reduces the charge transfer resistance and greatly increases the Li⁺diffusion coefficient.In this paper,a series of Co doped NM90 cathode materials are prepared by one-step calcination method.XRD shows that the Co doped Li Ni_0.9Mn_0.1O₂ cathode materials have obvious layered structure,among which the 1.5%Co doped NM90 cathode material have the lowest cation mixing arrangement.TEM shows that the Co doping concentration in NM90-1.5%Co decreases from outside to inside.Its capacity retention is 84.8%after 100 cycles at 1 C and the reversible capacity can reach 144.1 m Ah g^-1 at 10 C.In this paper,the dual modification strategy of Co doping and La₂O₃ coating to prepare a suitable cathode material for power batteries.Co doping can effectively widen layer spacing and reduce Li⁺/Ni²⁺mixing,and La₂O₃ coating can effectively eliminate the residual alkali on the surface of active material,inhibit the thickening of CEI film and reduce surface/interface side reactions.Therefore,the NM90-CL material with excellent electrochemical properties is achieved through the synergistic enhancement of Co doping and La₂O₃ coating.Its capacity retention rate can reach 77.9%after 200 cycles at 1 C,and 75.7%after 200 cycles at 5 C.Its reversible capacity can up to 153.5 m Ah g^-1 at 10 C.This dual modification strategy will provide theoretical guidance and technical support for the synthesis of other high performance electrode materials.