Enhanced rate capability and mitigated capacity decay of ultrahigh-nickel cobalt-free LiNi0.9Mn0.1O2 cathode at high-voltage by selective tungsten substitution

Abstract

Owing to the further requirement for electric vehicle market, it is appropriate to lower the cost and improve the energy density of lithium-ion batteries by adopting the Co-free and Ni-rich layered cathodes. However, their practical application is severely limited by structural instability and slow kinetics. Herein, ultrahigh-nickel cobalt-free LiNi0.9Mn0.1O2 cathode is elaborate designed via in-situ trace substitution of tungsten by a wet co-precipitation method following by high-temperature sintering. It is revealed that the in-situ doping strategy of high valence W6+ can effectively improve the structure stability by reducing irreversible phase transition and suppressing the formation of microcracks. Moreover, the transformed fine particles determined by W-doping can facilitate the kinetic characteristics by shortening Li+ diffusion paths. As expected, 0.3 mol% W-doped LiNi0.9Mn0.1O2 cathode exhibits a high specific capacity of 143.5 mAh/g after 200 cycles at high rate of 5 C in the wide potential range of 2.8-4.5 V, representing a potential next-generation cathode with low-cost, high energy-density and fast-charging capabilities.