Integrated Surface Modulation of Ultrahigh Ni Cathode Materials for Improved Battery Performance

Abstract

Ni-rich layered cathodes with ultrahigh nickel content (≥90%), for example LiNi 0.9 Co 0.1 O 2 (NC0.9), are promising for next-generation high-energy Li-ion batteries (LIBs), but face stability issues related to structural degradation and side reactions during the electrochemical process. Here, surface modulation is demonstrated by integrating a Li + -conductive nanocoating and gradient lattice doping to stabilize the active cathode efficiently for extended cycles. Briefly, a wet-chemistry process is developed to deposit uniform ZrO(OH) 2 nanoshells around Ni 0.905 Co 0.095 (OH) 2 (NC0.9-OH) hydroxide precursors, followed by high temperature lithiation to create reinforced products featuring Zr doping in the crust lattice decorated with Li 2 ZrO 3 nanoparticles on the surface. It is identified that the Zr 4+ infiltration reconstructed the surface lattice into favorable characters such as Li + deficiency and Ni 3+ reduction, which are effective to combat side reactions and suppress phase degradation and crack formation. This surface control is able to achieve an optimized balance between surface stabilization and charge transfer, resulting in an extraordinary capacity retention of 96.6% after 100 cycles at 1 C and an excellent rate capability of 148.8 mA h g −1 at 10 C. This study highlights the critical importance of integrated surface modulation for high stability of cathode materials in next-generation LIBs.

Long-Cycle Lithium Batteries with LiNi0.8Co0.1Mn0.1O2 Cathodes above 4.5V Enabled by Uniform Coating of Nanosized Garnet Electrolytes

“…As a consensus, the formation of particle cracks results from the significant lattice strain induced by the huge volume changes upon extensive Li + extraction/insertion during cycling, and the lattice strain would be aggravated upon charging at voltages higher than 4.3 V. [9][10][11][12] Many strategies have been proposed to stabilize the cathode surface and suppressing the particle cracking, such as lattice doping and surface modification. [13][14][15][16][17][18][19][20] As an economically practical method, surface coating with insulating oxides such as Al2O3, SiO2, and ZrO2 was widely used in current industry of Ni-rich cathode materials. With the merits of high ionic conductivity and wide electrochem-ical window, garnet-type oxide solid electrolytes attract extensive interests in recent decades, which are considered as the next generation coating material for high-energy cathodes.…”