A uniform and high-voltage stable LiTMPO4 coating layer enabled high performance LiNi0.8Co0.15Mn0.05O2 towards boosting lithium storage

LiTMPO4 materials, such as LiNiPO4, can maintain structural stability and Li+ transport activity up to 4.8 V, showing great potential to stabilize layered nickel-rich cathodes at high voltage. But achieving a uniform LiTMPO4 coating layer remains a great challenge. Herein, an ultrathin and uniform LiTMPO4 layer (mainly LiNiPO4) is successfully coated on the surface of LiNi0.8Co0.15Mn0.05O2 (NMC@LTMP) via utilizing the surface chelation of phytic acid with NMC precursors and a subsequent high-temperature in situ reaction. The reconstructed surface and interface could act as stable paths for Li+ transport and efficient barriers against electrolyte corrosion. Thus, harmful side reactions like solid electrolyte interphase overgrowth, irreversible phase transformation, and metal dissolution are inhibited simultaneously. Impressively, the optimized NMC@LTMP2 cathode exhibits remarkably improved capacity, as high as 215 mA h g-1 at 2.8-4.5 V, with capacity retention of 87.21% after 200 cycles and outstanding rate capability of 140 mA h g-1 at 10C, significantly better than a pristine cathode. Furthermore, a pouch cell assembled with an NMC@LTMP2 cathode and graphite anode also exhibits robust capacity retention of 82.42% after 100 cycles. These results provide useful insights towards enabling the application of NMC cathodes via developing facile modification methods.