水系混合电池正极材料Li_(3)V_(2-x)Cox(PO_(4))_(3)制备及其电化学性能  

Preparation and Electrochemical Properities of Cathode Material Li_(3)V_(2-x)Co_(x)(PO_(4))_(3)for Aqueous Hybrid Battery

作　　者：王伟 皮圣东 王诚 孙焱 熊利芝[2] 向延鸿[1] WANG Wei;PI Shengdong;WANG Cheng;SUN Yan;XIONG Lizhi;XIANG Yanhong(College of Physics and Electromechanical Engineering,Jishou University,Jishou 416000,Hunan China;College of Pharmacy,Jishou University,Jishou 416000,Hunan China)

机构地区：[1]吉首大学物理与机电工程学院,湖南吉首416000 [2]吉首大学药学院,湖南吉首416000

出　　处：《吉首大学学报（自然科学版）》2024年第4期67-75,共9页Journal of Jishou University(Natural Sciences Edition)

基　　金：国家自然科学基金资助项目(52264037,52064014,52265019,52064013);湖南省青年科技人才项目(2022RC1087);湖南省优秀青年基金项目(2023JJ10033,2022JJ40341);国家大学生创新训练计划项目(202110531002)。

摘　　要：以偏钒酸铵、二水醋酸锂、磷酸二氢铵为原料,以四水乙酸钴为Co元素掺杂源,采用冷冻干燥辅助溶胶凝胶法制备Co元素掺杂的磷酸钒锂前驱体,再采用分段煅烧方法获得Li_(3)V_(2-x)Co_(x)(PO_(4))_(3)(x=0,0.01,0.02,0.04,0.06)材料,在此基础上,进一步探究Co元素掺杂对材料结构和电化学性能的影响.结果表明,采用冷冻干燥辅助溶胶凝胶法能够获得结晶度良好的单斜结构晶体,适量Co元素掺杂没有改变磷酸钒锂的晶体结构;采用冷冻干燥辅助溶胶凝胶法合成的正极材料均呈微孔结构,适量Co元素掺杂有助于增加材料微孔数量,以获得颗粒尺寸更均匀的材料;随着Co元素掺杂量的增加,材料的离子扩散速率、充放电性能、循环倍率性能均呈现出先提高后降低的规律,电荷转移阻抗呈现出先减小后增大的规律;当x=0.04时,磷酸钒锂正极材料的电化学性能最佳,离子扩散速率高达8.99×10^(-13)cm^(2)/s,电荷转移阻抗低至233.6Ω,且在2C倍率下,首次放电比容量由未掺杂的53.4 mAh/g提升至81.7 mAh/g,2C倍率循环50次后放电比容量保持率为91.11%,与未掺杂样品相比,提升了13.54%.In this design,Li_(3)V_(2-x)Co_(x)(PO_(4))_(3)materials were synthesized by freeze-drying assisted sol-gel method,with ammonium metavanadate,lithium acetate dihydrate,and ammonium dihydrogen phosphate as raw materials,and cobalt acetate tetrahydrate as Co doping source.The effect of Co doping on the structural and electrochemical properties of the materials was investigated.The results show that Monoclinic crystals with good crystallinity can be obtained by freeze-drying assisted sol-gel method,and the crystal structure of lithium vanadium phosphate is not changed by proper Co doping.The positive electrode materials synthesized by freeze-drying assisted sol-gel have microporous structure.The proper amount of Co doping helps to increase the number of micropores and obtain the material with more uniform particle size.With the increase of Co doping amount,the ion diffusion rate,charge/discharge and cycling performance of the materials all presents a trend of first increasing and then decreasing,while the charge transfer impedance presents a trend of first decreasing and then increasing.When x=0.04,the electrochemical performance of the lithium vanadium phosphate cathode material is the best,the ion diffusion rate reached 8.99×10^(-13)cm^(2)/s,the charge transfer impedance is the lowest,233.6Ω,and the initial discharge capacity increases from undoped 53.4 mAh/g to 81.7 mAh/g at 2C discharge rate.After 50 weeks of 2C rate cycle,the discharge capacity retention rate is 91.11%,which is 13.54%higher than that of the undoped sample.

关 键 词：水系混合电池 正极材料 磷酸钒锂 冷冻干燥 掺杂 

分 类 号：TM912[电气工程—电力电子与电力传动]