Interface and lattice co-modification improve electrochemical performance and air-storage stability of nickel-rich cathode.

Nickel-rich layered oxides have stood out among cathode materials for lithium-ion batteries because of their inexpensive costs and large specific capacity. However, large-scale commercial uses of nickel-rich cathodes are constrained by structural degradation and air-storage instability. Herein, we synthetize a Mg and Nb co-modified LiNi0.8Co0.1Mn0.1O2 cathode (MgNb-NCM) through acid co-precipitation combined with solid-state reaction. Combining the characterizations of X-ray diffraction (XRD), in situ XRD, and high-resolution transmission electron microscopy (HRTEM), the results demonstrate that Mg2+ and Nb5+ doped into the crystal structures of NCM can reduce the Li+/Ni2+ mixing and alleviate irreversible H2-H3 phase. Meanwhile, through the interactions of Nb ion and residual lithium compounds, a nanoscale Li-Nb-O interfacial protective coating is created on the pristine NCM surface, which helps to suppress side reactions and strengthen the air storage stability of the NCM. After 100 cycles, the MgNb-NCM displays increased cycling stability with 92.9% capacity retention at 1C, much higher than NCM (79.9%). More importantly, the air-storage stability of NCM is highly improved by such co-modification. After 21 days of exposure to air, NCM presents structural degradation, and the capacity drops to 50.0 mAh g−1, while MgNb-NCM appears excellent structural stability, and the capacity retains 151.9 mAh g−1 with a higher capacity retention of 78.8% over 300 cycles at 1C. [ABSTRACT FROM AUTHOR]