钠锰比对Na_xMnO_2的性能和钠离子脱嵌过程的影响  

Influences of Na-Mn Ratio on Electrochemical Performances and Intercalation-Deintercalation Processes of Sodium Ion in Na_xMnO_2

作　　者：谢永纯 王成[1] 蒋芳 杨洋 苏静[1,2,3] 龙云飞 文衍宣[1,4,2,3] XIE Yong-chun;WANG Cheng;JIANG Fang;YANG Yang;SU Jing;LONG Yun-fei;WEN Yan-xuan(School of Chemistry of and Chemical Engineering,Guangxi University,Nanning 530004,China;Guangxi Key Laboratory of Processing for Non-ferrous Metallic and Featured Materials,Guangxi University,Nanning 530004,China;Guangxi Novel Battery Materials Research Center of Engineering Technology,Nanning 530004,China;Guangxi Colleges and Universities Key Laboratory of Novel Energy Materials and Related Technology,Nanning 530004,China)

机构地区：[1]广西大学化学化工学院,广西南宁530004 [2]广西新型电池材料工程技术研究中心,广西南宁530004 [3]广西有色金属及特色材料加工重点实验室,广西南宁530004 [4]广西高校新能源材料及相关技术重点实验室,广西南宁530004

出　　处：《电化学》2018年第4期375-384,共10页Journal of Electrochemistry

基　　金：国家自然科学基金资助项目(No.51564002)资助

摘　　要：采用高温固相法合成了Na_xMnO_2,并用X-射线衍射、X-射线光电子能谱、场发射扫描电镜、循环伏安、电化学阻抗谱和恒流充放电技术研究了钠锰比对材料的形态结构、电化学性能和钠离子脱嵌过程的影响.结果表明,Na_xMnO_2主要由Na_(0.7)MnO_2和Na_(0.91)MnO_2组成,且Na_(0.91)MnO_2的量随着钠锰比的增加而增加.随着钠锰比的增加,SEI膜扩散、界面电化学反应和固相扩散的活化能先减少后增大,而材料的放电比容量则先增大后减少.当钠锰比为0.80时,合成的材料1C倍率下首次放电比容量为152.8 m Ah·g-1,50次循环容量保持率为80.6%,5C大倍率下放电比容量为88.3 m Ah·g-1,表现出了良好的循环性能和倍率性,相应的SEI膜扩散、界面电化学反应和固相扩散过程的活化能分别为68.23、40.07和57.62 k J·mol-1.In this work, NaxMnO2 was synthesized by a solid-state reaction. The influences of Na：Mn ratio on the structure, morphology and electrochemical performance, and sodium ion intercalation/deintercalation processes were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge-discharge test. The prepared NaxMnO2 was mainly composed of Na（0.7）MnO2 and Na（0.91）MnO2, and the content of Na（0.91）MnO2 increased with the increase of Na：Mn ratio. However, the activation energy values of surface membrane diffusion, interfacial electrochemical reaction and Na＋ diffusion in the bulk material first decreased and then increased with the increase of Na：Mn ratio, while the discharge capability first increasedand then decreased with the increase of Na：Mn ratio. The sample synthesized with the Na：Mn ratio of 0.80 delivered a discharge capacity of 152.8 m Ah·g-1 with a capacity retention of 80.6% after 50 cycles at 1 C. Even being charged/discharged at 5 C, this sample still provided a discharge capacity of 88.3 m Ah·g-1, showing good cycle-stability and rate performance. The activation energy values of surface membrane diffusion, interfacial electrochemical reaction and solid-phase diffusion were found to be 68.23, 40.07 and 57.62 k J·mol-1, respectively.

关 键 词：钠离子电池 正极材料 NaxMnO2 钠离子脱嵌 

分 类 号：O646[理学—物理化学] TM911[理学—化学]