均匀沉淀法助力Li2ZrO3包覆LiNi0.85Co0.1Mn0.05O2提升电化学性能

Homogeneous Precipitation Assisted Li2ZrO3 Coating LiNi0.85Co0.1Mn0.05O2 for Improving Its Electrochemical Performance

高镍三元正极材料比容量随着Ni含量的增加而增加的特点与电动汽车亟待提高的续航里程相契合,但是高镍含量所带来的问题对其商业化应用不利。表面包覆可以有效抑制高镍含量对商业化的不利影响,但是非快锂离子导体包覆物会引入不利于锂离子传导的界面,而Li2ZrO3包覆可以有效避免这个问题。化学沉淀法因成本低廉和简单易行的特点在表面包覆中被广泛使用,而尿素则可以有效降低反应速度和提高反应的均匀性,因此本研究采用尿素辅助的化学沉淀法在高镍三元前驱体表面均匀沉淀Zr(OH)4,再经过同步混锂步骤合成锆酸锂包覆的高镍三元正极材料。材料表征结果表明:改良的化学沉淀法有助于形成均匀的包覆层,同步锂化的高温步骤会引发轻微的团聚,Li2ZrO3包覆可以改善高镍三元正极材料的表面化学环境。电化学性能测试显示Li2ZrO3包覆能提升高镍三元正极材料的电化学性能,有效抑制电荷转移阻抗的增长。

The specific capacity of Ni-rich cathode materials increases with the increase of Ni content,which corresponds to the endurance mileage of electric vehicle which needs to be improved urgently.However,surface coating can effectively inhibit the adverse effects of its shortcomings on commercialization,but common coatings can lead to the interface that is unfriendly to lithium ion transmission,while Li2ZrO 3 coating can effectively avoid this problem.Chemical precipitation method is widely used in surface coating because of its low cost and simplicity.Urea can effectively reduce the reaction rate and improve the uniformity of the reaction.Therefore,urea-assisted chemical precipitation method was used to precipitate Zr(OH)4 uniformly on the surface of precursor,and then Li 2ZrO3 coated Ni-rich cathode material was synthesized through synchronous lithiation.The material characterization shows that the improved chemical precipitation method is helpful to form a uniform coating layer,the high temperature step of synchronization lithization can cause agglomeration and Li 2ZrO3 surface coating can improve the chemical environment of Ni-rich cathode materials.The electrochemical performance test of the cathode material shows that Li 2ZrO3 coating can improve the electrochemical performance of Ni-rich cathode material and effectively inhibit the growth of charge transfer impedance.