High-entropy doping promising ultrahigh-Ni Co-free single-crystalline cathode toward commercializable high-energy lithium-ion batteries.

Liang, Longwei; Su, Maoshui; Sun, Zhefei; Wang, Lixian; Hou, Linrui; Liu, Haodong; Zhang, Qiaobao; Yuan, Changzhou · Sci Adv · 2024

basic_science · Level V

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Abstract

The development of advanced layered Ni-rich cathodes is essential for high-energy lithium-ion batteries (LIBs). However, the prevalent Ni-rich cathodes are still plagued by inherent issues of chemomechanical and thermal instabilities and limited cycle life. For this, here, we introduce an efficient approach combining single-crystalline (SC) design with in situ high-entropy (HE) doping to engineer an ultrahigh-Ni cobalt-free layered cathode of LiNi<sub>0.88</sub>Mn<sub>0.03</sub>Mg<sub>0.02</sub>Fe<sub>0.02</sub>Ti<sub>0.02</sub>Mo<sub>0.02</sub>Nb<sub>0.01</sub>O<sub>2</sub> (denoted as HE-SC-N88). Thanks to the SC- and HE-doping merits, HE-SC-N88 is featured with a grain-boundary-free and stabilized structure with minimal lattice strain, preventing mechanical degradation, reducing surface parasitic reactions, and mitigating oxygen loss. Accordingly, our HE-SC-N88 cathode demonstrates exceptional electrochemical properties particularly with prolonged cycling stability under strenuous conditions in both half and full cells, and the delayed O loss-induced phase transitions upon heating. More meaningfully, our design of HE doping in redefining the ultrahigh-Ni Co-free SC cathodes will make a tremendous progress toward industrial application of next-generation LIBs.