摘要
高镍LiNixCoyMn/Al1-x-yO2三元材料(高镍材料)因比容量高、能量密度大而成为最具前景的高能量密度锂电池正极材料之一.然而,随着Ni含量提升,高镍材料的结构、化学和机械稳定性逐渐恶化,严重限制了其产业化安全应用.鉴于此,本文首先对当前高镍材料的合成方法(固相法、溶解凝胶法、水热法、喷雾干燥法及共沉淀法)进行了综述.随后,总结了高镍材料合成、储存及使用过程中的关键失效机制,包括离子混排与不可逆相变、表面残碱与界面副反应、应力诱导微裂纹及过渡金属溶解等,并对其形成原因及演变过程进行了深入剖析;系统总结了高镍材料的主要改性方法,如离子掺杂、表面包覆、核壳/梯度材料设计及单晶材料设计等.最后,对高镍材料的未来发展及改进方向进行了展望.本文通过系统总结高镍材料的研究进展和不足,旨在为高能量密度型高镍材料的产业化制备及安全应用提供理论参考.
Abstract
Benefiting from high energy density and low cost,Ni-rich LiNixCoyMn/Al1-x-yO2 materials have received great attention as promising cathode candidates for next-generation high-energy lithium-ion batteries(LIBs)that are widely used in electric vehicles(EVs).However,with an increased Ni content,Ni-rich cathode materials suffer from severe structural,chemical,and mechanical instabilities,seriously restricting their industrially safe application in power LIBs of EVs.In this review,primarily,the synthesis methods of Ni-rich cathode materials are summarized in detail,which include solid-state method,sol-gel method,hydrothermal method,spray-drying method,and co-precipitation method.Subsequently,the key failure mechanisms,including ion mixing and irreversible phase transition,residual Li species and interface side reactions,mechanical microcracks,and transition metal dissolutions,are thoroughly analyzed throughout the preparation,storage,and service of Ni-rich cathode materials,thereby clarifying various performance decay behaviors of materials.The modification strategies that cover ion doping,surface coating,core-shell/gradient materials,and single-crystal materials are systematically discussed for Ni-rich cathode materials,aiming at presenting conspicuous research progress and current shortcomings for the stabilization of Ni-rich cathode materials.Finally,this review presents a perspective toward future development and optimization for Ni-rich cathode materials,aiming at delivering a theoretical guidance for propelling its industrial safe application in high-energy LIBs.
维普
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