B₂O₃/LiBO₂ dual-modification layer stabilized Ni-rich cathode for lithium-ion battery

Ni-rich layered oxide material with high theoretical capacity and low cost is one of the most promising cathode candidates for high-energy-density lithium-ion battery. However, increase of Ni content triggers structural instability and fast capacity degradation, which severely impedes the practical application of Ni-rich materials. Here, a surface dual-modification layer of B₂O₃ & LiBO₂ is introduced to Ni-rich material LiNi_0.89Co_0.08Mn_0.03O₂ (NCM89), which successfully stabilizes the layered structure of NCM89 during cycling as well as removes residual lithium in NCM89. The in-situ X-ray diffraction and cross-sectional scanning electron microscopy results demonstrate effectively improved structural reversibility and stability of the cathode. Moreover, the dissolution of transition metals and decomposition of electrolyte at the cathode/electrolyte interface are successfully suppressed, resulting in beneficial cathode electrolyte interphase (CEI) layer. As a result, the boron modified cathode exhibits s a high capacity of 180.4mAh g⁻¹ along with an excellent capacity retention of 90% after 100 cycles at 1C in 2.75–4.35 V at 25 °C, while the pristine NCM89 cathode only retains 59% of its initial capacity after 100 cycles. Furthermore, the capacity retention of full cell after 350 cycles is improved from 52.5% to 90%.