Improved electrochemical property of Ni-rich LiNi0.6Co0.2Mn0.2O2 cathode via in-situ ZrO2 coating for high energy density lithium ion batteries

Surface coating is an effective routine to improve the cycling stability and reversible capacity of nickel-rich LiNi0.6Co0.2Mn0.2O2 (NCM622) cathode in lithium ion batteries (LIBs), especially at high voltage. Herein, an amorphous Zirconium dioxide (ZrO2) coating modified NCM622 cathode materials are successfully prepared by in-situ method based on UiO-66. As the cathode material for LIBs, the in-situ ZrO2 coated NCM622 retains 82.5% capacity retentions over 2.8-4.5 V after 100 cycles, higher than those for the pristine NCM622, which are only 52.4%. Such significant improvements are mainly attributed that the homogeneous ZrO2 coating effectively stabilized the cathode/electrolyte interface. It is confirmed that the uniform ZrO2 coating layer suppressed the structural degradation induced by detrimental side reactions with electrolyte. Meanwhile, the unique porous framework of UiO-66 also provides massive active sites on the NCM622 surface, keeping the lithium diffusion even at a high level upon cycling. The in-situ synthesized method provides an available and simple modifying strategy for high performance ZrO2-coated cathode materials at high voltage.