通过Mo掺杂诱导低Li/Ni混排程度增强Li_(1.2)Ni_(0.13)Fe_(0.13)Mn_(0.54)O_(2)可逆容量与循环稳定性  

Enhancing reversible capacity and cycling stability of Li_(1.2)Ni_(0.13)Fe_(0.13)Mn_(0.54)O_(2) by inducing low Li/Ni misalignment through Mo doping

作　　者：冉沛林 吴康 赵恩岳 王芳卫 毋志民[1] Ran Pei-Lin;Wu Kang;Zhao En-Yue;Wang Fang-Wei;Wu Zhi-Min(College of Physics and Electronic Engineering,Chongqing Normal University,Chongqing 401331,China;Songshan Lake Materials Laboratory,Dongguan 523808,China;Beijing National Laboratory for Condensed Matter Physics,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China)

机构地区：[1]重庆师范大学物理与电子工程学院,重庆401331 [2]松山湖材料实验室,东莞523808 [3]中国科学院物理研究所,北京凝聚态物理国家研究中心,北京100190

出　　处：《物理学报》2024年第2期302-309,共8页Acta Physica Sinica

基　　金：重庆市教委科学技术研究计划重点项目(批准号:KJZD-K202300512);国家自然科学基金(批准号:52088101,12105197)资助的课题。

摘　　要：富锂层状氧化物因能量密度高和成本低,有望成为下一代锂离子电池正极的重要候选材料.然而,富锂正极材料中阴离子氧化还原反应使晶格氧不稳定,导致电压衰减和不可逆容量损失.尽管铁代无钴富锂材料可以实现较少的电压衰减,但存在严重的阳离子混排和较差的动力学.采用一种简单易行的高价离子掺杂策略,在Li_(1.2)Ni_(0.13)Fe_(0.13)Mn_(0.54)O_(2)(LNFMO)中掺入Mo元素,拓宽了锂层间距,为Li^(+)的传输提供了更宽的通道,改善了Li^(+)的扩散动力学,有效抑制了阳离子混排,进一步稳定了层状结构.得益于此,Mo掺杂后的富锂材料表现出显著增强的电化学性能,在0.2 C电流密度下表现出209.48 mAh/g的初始放电比容量.1C下的初始放电比容量从137.02 mAh/g提高到165.15 mAh/g;循环300次后,仍有117.49 mAh/g的放电比容量,电压衰减由2.09 mV/cycle降低为1.66 mV/cycle.本文对Mo掺杂后的正极材料进行了系统表征并揭示了循环稳定的机理,为高性能富锂正极材料的设计提供了重要参考.Li-ion batteries(LIBs)are widely used in mobile devices and electric vehicles,but the traditional layered transition metal cathode material,LiTMO_(2)(TM=Ni,Co,Mn,or Al),has a low energy density that cannot satisfy the demand of commercial applications.The Li-rich Mn-based layered oxides(LRLOs)are a strong competitor to the traditional layered cathode materials for their specific capacity of more than 200 mAh/g.Due to the high energy density and low cost,Li-rich Mn-based layered oxides(LRLO)have been a promising candidate cathode for next-generation Li-ion batteries.The anionic redox reaction(ARR)in LRLO destabilizes the lattice oxygen,leading to voltage degradation and capacity loss.Although iron-substituted cobalt-free Lirich materials can achieve less voltage decay,they suffer severe cation disorder and poor kinetics.Here,we develop a simple and feasible high-valent ion doping strategy by doping Mo into Li_(1.2)Ni_(0.13)Fe_(0.13)Mn_(0.54)O_(2)(LNFMO),which expands the Li layer spacing and provides a broader channel for Li^(+)transport,thereby improving the diffusion kinetics of Li^(+),effectively suppressing the cation disorder,and further stabilizing the layered structure.As a result,the Mo-doped LRLO exhibits significantly enhanced electrochemical performance,with an initial reversible capacity of 209.48 mAh/g at 0.2 C,and the initial specific capacity increasing from 137.02 mAh/g to 165.15 mAh/g at 1 C.After 300 cycles,specific capacity remains 117.49 mAh/g for the Modoped cathode,and the voltage decay decreases from 2.09 mV/cycle to 1.66 mV/cycle.The Mo-doped LRLO is systematically characterized,and the mechanism of cycle stabilization is revealed,which provides an important reference for designing high performance Li-rich cathode.

关 键 词：锂离子电池 富锂层状氧化物 正极材料 阳离子混排 

分 类 号：TB34[一般工业技术—材料科学与工程] TM912[电气工程—电力电子与电力传动]