Li metal batteries pairing Li metal anode with high-nickel layer structured oxide cathode are a promising energy storage technology to achieve high energy density. To obtain long cycling life for Li metal batteries, the electrolyte plays a pivotal role in stabilizing both the Li metal anode and the high-nickel cathode upon electrochemical cycling. Herein, we report a carbonate electrolyte that enables a Li∥Li-Ni 0.8 Mn 0.1 Co 0.1 O 2 pouch cell to achieve a high gravimetric energy density of 366 Wh/kg and unprecedented cycling stability with 80% capacity retention after 335 cycles. The 19 F quantitative nuclear magnetic resonance spectroscopy and interface characterization demonstrate that FEC and LiDFOB can reduce the consumption rate of each other and the electrolyte, form a robust LiF-rich SEI on Li metal anode, and improve the microstructure integrity of the high-nickel cathode.

Cathode material with high nickel content is a promising candidate for the future generation of Li-ion batteries (LIBs). However, severe structural degradation during cycling limits its practical use, especially for electric vehicles. Herein, AlPO4 nanoparticles were synthesized and then coated onto the surface of a high-nickel layer-structured cathode via a dry coating method. The AlPO4 nanoparticles coating significantly improved the cycling stability from 69.2% to over 80% capacity retention after 140 cycles. Furthermore, the structure and chemical composition of the AlPO4-coated cathode was investigated by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and scanning-tunneling electron microscopy. Compared with the non-coated cathode, we revealed a dual protective mechanism for the enhanced cycling stability, where Al doping and Li3PO4 coating play synergistic roles in protecting cathode material through long-term cycling. This work demonstrates a facile and environmentally friendly approach towards improving the performance of high-nickel LIB cathodes, which can be easily scaled up for industrial applications.