Supplying active lithium to single-crystal Li(Ni0.90Co0.05Mn0.05)0.98Ta0.02O2 with Li2MnO3 coating served as cathode for Li-ion batteries

Abstract

Ni-rich layered oxide with Ni molar content larger than 90% was regarded as an extremely promising candidate for cathode material applied in lithium-ion batteries owing to the significant discharging capacity and low cost. Nevertheless, rigorous cycling attenuation resulted from the crystal structure collapse and unstable particles interface deeply restrained the commercial application. In the work, LiNi_0.90Co_0.05Mn_0.05O₂ was modified by Ta⁵⁺ doping and Li₂MnO₃ covering, which was aimed to enhance the structure stability, defend the electrolyte attacking and promote Li⁺ migration during cycling. The material characterization demonstrated the cathodes after Ta⁵⁺ doping delivered the larger cell lattice parameters and higher cation ordering, which was helpful to improve the rate property and discharge capacity at low temperature. The Li₂MnO₃ layer was tightly adhered on the outside of LiNi_0.90Co_0.05Mn_0.05O₂, which could effectively relieve the electrolyte attacking and sustain the particle morphology integrity. As a result, 2 wt% Li₂MnO₃ coated Li(Ni_0.90Co_0.05Mn_0.05)_0.98Ta_0.02O₂ exhibited the outstanding discharge capacity of 150.2 mAh g⁻¹ at 10.0 large current density and 140.6 mAh g⁻¹ at −30 °C as well as the remarkable capacity retention of 93.1% after 300 cycles. Meanwhile, the pouch full batteries obtained by 2 wt% Li₂MnO₃ coated Li(Ni_0.90Co_0.05Mn_0.05)_0.98Ta_0.02O₂ also showed the more stable storage capability, cyclic property in comparison with bare LiNi_0.90Co_0.05Mn_0.05O₂.