Synergistic Modification and Mechanism of Tungsten and Niobium to Enhance the Performance of Nickel‐Rich Layered Cathode Materials

Abstract To improve the capacity at a high rate and cycle stability of LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811), a simple strategy is developed to synthesize the tungsten/niobium (W/Nb) co‐doped cathode material. W/Nb co‐doping remarkably reduced the system energy of single W‐ or single Nb‐doping. The co‐doping makes the material have a more stable structure, and inhibits the anisotropic volume change caused by H2↔H3 phase transition, thus maintaining the integrity of particles and preventing the formation of microcracks. Moreover, the passivation layer formed by co‐doping prevents the occurrence of side reactions as well as the formation of microcracks. The synergistic effect of W and Nb is also conducive to inhibiting the formation of internal oxygen vacancies and surface Li 2 CO 3 . For the W/Nb co‐doped sample, the capacity retention of 54.9% after 400 cycles and 52.3% after 500 cycles are maintained even at high currents of 5.0 and 10.0 C, respectively. The strategy of synergistic effect on enhancing co‐doping with high valence cations can be spread as a simple and practical method to improve the electrochemical performance of nickel‐rich layered cathode materials for lithium‐ion batteries at high cut‐off voltage.