Abstract
Li3PO4@Li0.99K0.01Ni0.83Co0.11Mn0.06O2(NCM-KP)cathode powders are synthesized via K+dop-ing in calcination processes and H3PO4 coating in sol-gel processes.K+precisely enters into the lattice to widen the(003)plane to 0.4746 nm with a lower cationic disordered degree of 1.87％.Moreover,the surface residual lithium salts are treated by H3PO4 to generate a uniform Li3PO4 coating layer of approximately 11.41 nm,which com-pletely covers on the surface of secondary spherical parti-cles to improve the interfacial stability.At 25 ℃,the NCM-KP electrode delivers a discharge specific capacity of 148.9 mAh·g-1 with a remarkable capacity retention ratio of 84.1％after 200 cycles at 1.0C and retains a high reversible specific capacity of 154.4 mAh·g-1 at 5.0C.Even at 1.0C and 60 ℃,it can maintain a reversible dis-charge specific capacity of 114.6 mAh·g-1 with 0.21％of capacity decay per cycle after 200 cycles,which is sig-nificantly lower than 0.40％for the pristine NCM powders.Importantly,the charge transfer resistance of 238.89 Ω for the NCM-KP electrode is significantly lower than 947.41 Ω for the pristine NCM one by restricting the interfacial side reactions.Therefore,combining K+doping and Li3PO4 coating is an effective strategy to enable the significant improvement of the electrochemical property of high-nickel cathode materials,which may be mainly attributed to the widened diffusion pathway and the formed Li3PO4 protective layer,thus promoting Li+diffusion rate and preventing the erosion of HF.
基金项目
National Natural Science Foundation of China(52274292)
National Natural Science Foundation of China(51874046)
Outstanding Youth Foundation of Hubei Province(2020CFA090)
NETL
NSTL
万方数据