调控钠位点占比设计高性能P2型钠电正极材料  

High Performance Na-Based P2-Type Cathodes Designed by Na Sites Modulation

作　　者：韩嘉俊 温敏 郑其林 袁伟伟 陈康 廖俊杰 姚胡蓉 HAN Jiajun;WEN Min;ZHENG Qilin;YUAN Weiwei;CHEN Kang;LIAO Junjie;YAO Hurong(School of Physics and Energy,Fujian Normal University,Fuzhou 350117,China;Fujian Collaborative Innovation Center for Advanced High-Field Superconducting Materials and Engineering,Fuzhou 350117,China)

机构地区：[1]福建师范大学物理与能源学院,福州350117 [2]福建省先进高场超导材料与工程协同创新中心,福州350117

出　　处：《硅酸盐学报》2024年第6期2016-2023,共8页Journal of The Chinese Ceramic Society

基　　金：国家自然科学基金面上项目(22179021);福建省杰出青年项目(2023J06028)。

摘　　要：在众多Na离子电池正极材料中,P2型层状氧化物因其优异的动力学性能受到研究者们的广泛关注。在P2型层状氧化物材料中,Na离子有2种不同的位点,即Na_(e)和Na_(f)。由于配位环境的差异,Na离子在不同位点间的迁移行为不同。本工作提出通过调控材料中Na含量的策略实现了对同一过渡金属组分材料的/Na_(f)位点占位比的优化。研究发现,与Na_(0.45)Ni_(0.1)Mn_(0.9)O_(2)和Na_(0.65)Ni_(0.1)Mn_(0.9)O_(2)相比,具有更高Na_(e)/Na_(f)位点占比值的Na_(0.55)Ni_(0.1)Mn_(0.9)O_(2)材料表现出最为优异的电化学性能,其电化学曲线平滑,在0.2 C (1 C=173 m A·g^(-1))的倍率下容量高达174.5 m A·h·g^(-1),在3 C,循环200次容量保持率高达92.95%,10 C的高倍率下仍能发挥83.6 mA·h·g^(-1)的容量,该策略为设计高性能P2型钠电正极材料打开了新的思路。Introduction Na-ion batteries(NIBs)have a great potential as next-generation large-scale energy storage devices.Among various cathode materials for NIBs,P2-type layered transition metal oxides have attracted much attention because of their excellent kinetics and easy processability.In P2-type layered oxides,Na ion occupies two different sites,i.e.,Na_(e) and Na_(f).The triangular prism polyhedron of Na_(f) site shares faces with two TmO6 octahedrons,while Na_(e) shares edges with six TmO6.The migration behavior of Na ions at different positions is diverse due to the distinction of distance and electrostatic force between Na+−Tmn+.The migration of Na ions at Na_(e) site has a lower migration energy barrier,compared to that of Na_(f) position.Namely,more Na ions at Na_(e) site and increasing the occupation ratio of Na_(e)/Na_(f) can effectively improve the electrochemical performance of P2 layered oxides.Previous research indicates that the ratio of Na ions at different sites can be modulated by introducing inactive ions to transition metal layers.However,the introduction inevitably results in the capacity sacrifice.The ration of Na_(e)/Na_(f) is mainly affected by two aspects,i.e.,the interaction between Tmn+and Na+,and the interaction between Na+and Na+.In the case with the same transition metal component,the design of Na content is expected to achieve the regulation of Na_(e)/Na_(f) ratio,mainly from the following three reasons:1)Na content affects the valence state of transition metals,and thus modulates the interaction between Tmn+and Na+;2)Na content changes the Na interlayer distance,and then affects the distance between Na+and Tmn+and the corresponding interaction between Na+and Tmn+;and 3)Na content regulates the distance between Na+and Na+.In this paper,we proposed a novel strategy to optimize the Na_(e)/Na_(f) occupancy ratio with the same transition metal composition via adjusting Na content in the material.This strategy could open up new opportunities to design high-performance cathode materials for

关 键 词：Na离子电池 P2型层状正极材料 Na位点 

分 类 号：TQ174.75[化学工程—陶瓷工业]