摘要
以FeSO_(4)·7H_(2)O、MnSO_(4)·H_(2)O、NH_(4)H_(2)PO_(4)、CH_(3)COONa、一水合柠檬酸和氧化石墨烯(GO)为原料,采用溶胶-凝胶法制备了Mn^(2+)掺杂、还原氧化石墨烯(rGO)包覆的聚阴离子型钠离子电池正极材料Na_(4)Fe_(3–x)Mn_(x)(PO_(4))_(2)(P_(2)O_(7))/rGO(Mn_(x)-NFPP/rGO,x为Mn掺杂量,即Mn取代Fe的物质的量)。采用SEM、XRD、EDS、XPS对Mn_(x)-NFPP/rGO的微观形貌和结构成分进行了表征。通过恒流充放电、循环伏安和电化学阻抗测试,考察了Mn^(2+)掺杂量对Mn_(x)-NFPP/rGO电化学性能的影响,采用密度泛函理论计算了Mn_(x)-NFPP/rGO的能带和态密度。结果表明,Mn^(2+)掺杂扩大了Na^(+)扩散通道,提高了Na^(+)扩散速率,但对材料的三维结构和形貌没有影响;Mn_(0.30)-NFPP/rGO表现出最优的循环稳定性和倍率性能,在0.05 C倍率下具有131.2 mA·h/g的初始放电比容量,在2 C倍率下的放电比容量为91.9 mA·h/g;Mn^(2+)掺杂和rGO包覆有效提高了材料的放电比容量和循环稳定性,在1 C倍率下循环100圈后的比容量保持率为94%。Mn^(2+)的掺杂降低了材料价带与导带之间的带隙(3.128 eV),使价带中的电子更容易跃迁到导带,从而有利于提高Na^(+)的扩散动力学和本征电导率。
Mn^(2+)-doped(relative doping amount x,the same below)and reduced graphene oxide(rGO)-coated polyanionic sodium-ion battery cathode materials Na_(4)Fe_(3–x)Mn_(x)(PO_(4))_(2)(P_(2)O_(7))/rGO(Mn_(x)-NFPP/rGO,x represents the doping amount of Mn,that is the amount of substance where Fe is replaced by Mn)were prepared from FeSO_(4)•7H_(2)O,MnSO_(4)•H_(2)O,NH_(4)H_(2)PO_(4),CH_(3)COONa,citric acid monohydrate and graphene oxide(GO)by sol-gel method,and characterized by SEM,XRD,EDS and XPS for microstructure and composition analysis.The effect of the doping amount of Mn^(2+)on the electrochemical performance of Mn_(x)-NFPP/rGO was evaluated via galvanostatic charge-discharge,cyclic voltammetry and electrochemical impedance tests,while the energy band and state densities of Mn_(x)-NFPP/rGO was calculated by density functional theory.The results showed that Mn^(2+)doping expanded the Na^(+)diffusion channels and enhanced the Na^(+)diffusion rate,but had no influence on the three-dimensional structure and morphology of the material.Mn_(0.30)-NFPP/rGO exhibited the best cycle stability and rate performance,with an initial discharge specific capacity of 131.2 mA·h/g at 0.05 C and a discharge specific capacity of 91.9 mA·h/g at 2 C.Mn^(2+)doping and rGO coating effectively improved the discharge specific capacity and cycle stability of the material,with a specific capacity retention rate of 94%after 100 cycles at 1 C.Mn^(2+)doping reduced the band gap between the valence band and conduction band(3.128 eV)of the material,and made the electrons in the valence band more easily transition to the conduction band,which was conducive to improving the diffusion kinetics and intrinsic conductivity of Na^(+).
作者
闫共芹
谢相飞
蓝春波
赵卓凡
王晨
武桐
YAN Gongqin;XIE Xiangfei;LAN Chunbo;ZHAO Zhuofan;WANG Chen;WU Tong(School of Mechanical and Automotive Engineering,Guangxi University of Science and Technology,Liuzhou 545616,Guangxi,China;Jiangsu Zhenxi Technology Co.,Ltd.,Wuxi 214072,Jiangsu,China)
出处
《精细化工》
北大核心
2025年第9期1951-1959,共9页
Fine Chemicals
基金
广西自然科学基金项目(2020GXNSFAA159024)
广西高校中青年教师科研基础能力提升项目(2022KY0350)
广西汽车零部件与整车技术重点实验室自主课题(2023GKLACVTKF03)。
