Suppressing the H2–H3 phase transition of LiNi0.90Co0.04Mn0.03Al0.03O2 cathodes via Ta doping towards improved electrochemical performance upon 4.5V

Nowadays, Ni-rich cathodes act as a strong contender for high performance lithium-ion batteries cathodes due to their high capacities. Rapid capacity degradation and poor rate performance at high working voltages hinder their commercialization. This study reports a strategy for Ta5+ doping modification in LiNi0.90Co0.04Mn0.03Al0.03O2 (NCMA) cathode via a solid-state route. This study confirmed that the introduction of strong Ta–O bond is beneficial to degrade H2–H3 phase transition during cycling. Subsequently, the polarization of electrodes and internal resistance have been alleviated since the H2–H3 phase transition of the Ta-doped NCMA cathode is suppressed, which eventually leads to a high cyclability. Moreover, it also confirmed that the diffusion of Li ions has been accelerated since the space of Li layer is enhanced. As a consequence, the Ta-NCMA cathode displays a high initial discharge capacity of 222.6 mA h·g−1 and outperforms the benchmarking cathodes in 100th capacity retention (from 43.7% to 91.8%) between 2.8 and 4.5 V. Besides, compared to pristine NCMA cathodes, the rate capability of Ta5+-doped NCMA cathodes cycling at 5C also increase from 112.2 mA h·g−1 to 167.2 mA h·g−1. Hence, Ta doped Ni-rich cathode should be a potential cathode to realize both high capacity and stability structure.