Optimizing the interface engineering and structural stability of nickel-rich layered oxide cathode by dual-function modification

Abstract

Nickel-rich layered LiNi1-x-yCoxMnyO2 (1-x-y ≥ 0.6) cathode material has the advantage of high energy density, which is one of the hot topics in the field of new energy technology. Nonetheless, the nickel-rich layered oxide has serious interfacial and structural problems, resulting in unsatisfactory cycle performance and safety performance, which hinders large scale applications in the field of lithium-ion batteries. Here, a double modified LiNi0.82Co0.13Mn0.05O2 cathode material was prepared by a simple synthesis process with Zr4+ doping and LiBO2 coating, and has shown outstanding electrochemical performance. The initial discharge specific capacity is 200.8 mAh/g at 0.1C, and the capacity retention rate is also as high as 90.8% after 250 cycles at 1C. In-situ X-ray diffraction tests and density-functional theory calculations further reveal that the bulk Zr4+ doping is not only beneficial to maintain the stability of the crystal structure, but also to optimize the energy band structure of the material and increase the migration rate of lithium-ion. Moreover, the LiBO2 coating on the surface can effectively prevent the active material from directly contacting the electrolyte, and inhibit side reactions. The concept of “thick electrode” is introduced, and assembled into a pouch-type full cell with graphite as the anode, the high energy density is 302.8 Wh/kg and the retention rate after 1000 cycles is more than 80%. The safety performance test also shows that the nickel-rich layered oxide cathode has broad commercial potential application prospects.