一步法合成碳包覆Na_(0.44)MnO_(2)正极材料的制备及电化学性能  

Preparation and Electrochemical Performance of Carbon-coated Na_(0.44)MnO_(2)Cathode Material Synthesized by One-step Method

作　　者：张威龙 李桦林 庞刚 张庆安 ZHANG Weilong;LI Hualin;PANG gang;ZHANG Qingan(School of Materials Science&Engineering,Anhui University of Technology,Maanshan 243032,China)

机构地区：[1]安徽工业大学材料科学与工程学院,安徽马鞍山243032

出　　处：《安徽工业大学学报（自然科学版）》2024年第3期248-255,共8页Journal of Anhui University of Technology（Natural Science）

基　　金：国家自然科学基金项目(52171197)。

摘　　要：以MnCO_(3)为锰源,Na_(3)C_(6)H_(5)O_(7)•2H_(2)O为碳源和钠源,采用一步固相法制备碳包覆Na_(0.44)MnO_(2)(NMO/C)正极材料,对材料的晶体结构、微观组织形貌进行表征分析,探究Na_(3)C_(6)H_(5)O_(7)•2H_(2)O和Na_(2)CO_(3)对Na_(0.44)MnO_(2)晶体结构的影响;采用NMO/C组装纽扣电池进行循环伏安和首圈充放电测试,探究NMO/C材料的电化学性能。结果表明:NMO/C材料具有三维隧道结构,空间群为Pbam,形貌为长棒状,且表面均匀包覆一层2~3 nm的碳层;NMO/C正极材料表现出比较优异的长循环寿命和倍率性能,0.5 C倍率下的首圈放电比容量为113.1 mAh•g^(−1),循环1000圈后的放电比容量仍有74.1 mAh•g^(−1),容量保持率为65.5%;0.1,0.2,0.5,1.0,2.0 C倍率下的放电比容量分别为121.1,115.7,113.4,110.3,103.9 mAh•g^(−1),这是由于碳包覆层不仅可提高Na_(0.44)MnO_(2)正极材料的导电性,还可阻碍其与电解液直接接触,抑制Mn3+的溶解,致使NMO/C材料表现出优异的电化学性能。Taking MnCO_(3)as manganese source and Na_(3)C_(6)H_(5)O_(7)•2H_(2)O as carbon and sodium sources,the carbon-coated Na_(0.44)MnO_(2)(NMO/C)cathode material was prepared by one-step solid-state reaction.Its crystal structure and microstructure morphology were analyzed to explore the influence of Na_(3)C_(6)H_(5)O_(7)•2H_(2)O and Na_(2)CO_(3)on the crystal structure of NMO/C.The coin cells assembled with NMO/C were constructed the cyclic voltammetry and first charge and discharge tests to investigate the electrochemical performance of NMO/C materials.The results indicate that the NMO/C materials has three-dimensional tunnel structure with the space group of Pbam,and its morphology is a long rod-like particle,which is covered uniformly with 2–3 nm carbon layer.When is used as the cathode material of sodium-ion half cells,the NMO/C cathode materials shows excellent long-term cycling stability and rate performance,with discharge specific capacity of 113.1 mAh•g^(−1)for the first cycle and 74.1 mAh•g^(−1)after 1000 cycles at 0.5 C,which the capacity retention is 65.5%.The discharge specific capacities are 121.1,117.4,112.7,105.6,and 98.3 mAh•g^(−1)at at rates of 0.1,0.2,0.5,1.0,2.0 C,respectively.These improvements are attributed to the carbon-coating layer,which can not only effectively improve the electrical conductivity of the Na_(0.44)MnO_(2),but also hinder its direct contact with the electrolyte and inhibit the dissolution of Mn3+.Therefore,the carbon-coated Na_(0.44)MnO_(2)cathode material shows excellent electrochemical performance.

关 键 词：钠离子电池 Na_(0.44)MnO_(2) 三维隧道结构 碳包覆 电化学性能 

分 类 号：TQ131.12[化学工程—无机化工] TM912[电气工程—电力电子与电力传动]