▌Dual-Functional Surface Engineering of Single-Crystal NMC Cathodes via Residue-to-Coating Conversion for Enhanced Interface Stability
以殘留物轉化塗層的雙功能表面工程強化單晶 NMC 正極界面穩定性
S. A. Ahmed, T. Agnihotri, A. Ranjan, C. Y. Chang, R. Hasan, E. B. Tamilarasan, Y. Nikodimos, K. N. Shitaw, T. I. Yeh, B. W. Taklu, W. S. Liao, V. Boligarla, S. H. Wu*, W. N. Su* and B. J. Hwang*
https://doi.org/10.1002/smll.202506613
SEED Member: B. J. Hwang, W. N. Su, S. H. Wu, Y. Nikodimos

Major Contributions
1. LiH₂PO₄ wet impregnation converts surface residues (LiOH, Li₂CO₃) on single-crystal Ni-rich NMC into a uniform ~4 nm Li₃PO₄ protective coating, simultaneously eliminating harmful residues without solvent washing and forming a stable SEI-like interphase confirmed by in situ GC-MS and titration.
2. The Li₃PO₄ coating suppresses Ni migration, mitigates electrolyte-induced side reactions, and preserves Ni oxidation states over cycling, as confirmed by synchrotron XAS and post-mortem analysis.
3. Electrochemical testing shows 72.96% capacity retention after 100 cycles at 0.2C (vs. 18.25% for pristine SCNMC), along with improved rate capability and Li⁺ diffusion kinetics.
主要貢獻
1. LiH₂PO₄ 濕法浸漬將單晶鎳富 NMC 表面殘留物(LiOH、Li₂CO₃)轉化為均勻約 4 nm 的 Li₃PO₄ 保護塗層,無需溶劑洗滌即可同時消除有害殘留物並形成穩定界面,由原位 GC-MS 與滴定分析確認。
2. Li₃PO₄ 塗層抑制 Ni 遷移、減少電解液誘導的副反應並在循環過程中保持 Ni 氧化態,經同步輻射 XAS 與事後分析確認。
3. 電化學測試顯示在 0.2C 下 100 次循環後容量保持率為 72.96%(純 SCNMC 僅 18.25%),同時改善倍率性能與 Li⁺ 擴散動力學。





