Sodium doping derived electromagnetic center of lithium layered oxide cathode materials with enhanced lithium storage

High-voltage high-nickel low-cobalt lithium layered oxide cathode materials show great application prospects for lithium-ion batteries because of their low cost and high capacity. Unfortunately, the deterioration of the bulk structure and electrode-electrolyte interface will significantly deteriorate the cycle life and thermal stability of the battery as the nickel content and voltage increase. Here we introduce the 2 mol% Na-doped Li0.98Na0.02Ni0.6Co0.05Mn0.35O2 (NCM-Na) high-nickel low-cobalt cathode. Na ion plays the role of an electromagnetic center and effectively inhibits the harmful phase transitions and Li+/Ni2+ mixing, thereby greatly improving the lithium storage performance of the cathode material. NCM-Na delivers a higher capacity retention rate (93.3% vs. 83.2%) after 100 cycles and a superior rate capacity (121 mAh g-1 vs. 93 mAh g-1) at 3C current density compared to the pristine NCM under 4.5 V high voltage. And the improved lithium diffusion kinetics, bulk layered structure stability, electrode-electrolyte interface stability, and thermal stability are also confirmed through the relevant in/ex-situ characterization and theoretical calculation simulation. These beneficial effects also make the designed graphite anode high voltage full battery exhibit excellent electrochemical performance. This work provides a valuable strategic guideline for the use of high-voltage high-nickel low-cobalt cathodes in lithium-ion batteries.

Automated summary

Na-doped high-nickel low-cobalt cathode materials can greatly improve the lithium storage performance and cycle life, as well as enhance the electrode-electrolyte interface and thermal stability.