Multiscale Crystal Field Effect for High-Performance Ultrahigh-Ni Layered Cathode
Further popularization of ultrahigh-Ni layered cathodes for high-energy lithium-ion batteries (LIBs) is hampered by their grievous structural and interfacial degeneration upon cycling. Herein, by leveraging the strong electronegativity and low solubility properties of Sb element, a multifunctional modification that couples atomic/microstructural reconstruction with interfacial shielding is well designed to improve the LiNi0.94Co0.04Al0.02O2 (NCA) cathode by combining Sb5+ doping and Li7SbO6 coating. Notably, a robust O framework is established by regulating local O coordination owing to the incorporation of a strong Sb–O covalence bond, leading to the inhibited lattice O evolution at high voltage, as revealed by synchrotron X-ray absorption spectroscopy. Moreover, the radially aligned primary particles with (003) crystallographic texture and refined/elongated sizes are achieved by the pinning of Sb on grain boundaries and are confirmed by scanning transmission electron microscopy, resulting in the fast Li+ diffusion and mitigated particle cracking. Additionally, in situ construction of the Li7SbO6 ionic conductive layer on grain boundaries can effectively boost interfacial stability and Li+ kinetics. As a result, the optimal Sb-modified NCA delivers a high capacity retention of 94.6% after 200 cycles at 1 C and a good rate capacity of 183.9 mAh g–1 at 10 C, which is expected to be applied to next-generation advanced LIBs.
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