Customized Design of Biobased Elastomeric Antioxidative Interphase for High‐Voltage Ni‐Rich Cathodes

High-voltage (≥4.5 V) Ni-rich cathodes can help advance the development of the next generation of high-energy lithium-ion batteries. However, the high voltage used in Ni-rich cathodes deteriorates the cycling performance due to the structural disintegration of polycrystalline particles and electrolyte decomposition. Herein, a robust protective layer with high-voltage tolerance is applied to the surface of Ni-rich cathodes to address these challenges. The protective layer consists of a crosslinked bio-based elastomer (CBE) whose main chain is connected by saturated bonds, which confers high-voltage tolerance. CBE is an elastic material with viscoelastic properties, allowing it to serve as an energy dissipation layer that mitigates strain accumulation and preserves the structural integrity of the coated Ni-rich cathode. CBE also shows high polarity and rapid lithium-ion transport capabilities due to the presence of oxygen-containing components, which ensures tight wrapping of Ni-rich cathodes and improves their interfacial reaction kinetics. As anticipated, the 4.5 V Li||LiNi_0.6Co_0.2Mn_0.2O₂ batteries exhibit an initial capacity of 176.7 mA h g^-1 and a capacity retention rate of 79.5% after 400 cycles. This study underscores the critical role of a customized protective layer in stabilizing Ni-rich cathodes at high voltages.