Multi-Level Engineering from Surface to Bulk Enabling Highly Stable Ni-Rich O3-Type Cathode toward...

The pursuit of high-capacity Na-ion batteries (NIBs) has propelled great forward the O3-type Ni-rich NaNi_0.5Co_0.2Mn_0.3O₂ (NCM) cathodes. However, the inborn chemo-mechanical instabilities caused by complex phase transitions and anisotropic lattice stress have severely delayed its widespread application. In the contribution, a cooperative surface-to-bulk modification strategy, i.e., in situ surface NaTi₂(PO₄)₃ (NTP) coating and bulk Ti/F co-doping, is first proposed to engineer an advanced NCM cathode (denoted as TF-NCM@NTP). The NTP protective layer with high thermodynamic stability and ionic conductivity endows TF-NCM@NTP with a highly stable interface and expedited de-/sodiated kinetics. The robust Ni/Co/Mn─F bond and concurrent Ti─O bond greatly strengthen the bulk lattice oxygen and mitigate the internal strain self-reproduction. Benefiting from these synergistic merits, the designed TF-NCM@NTP cathode demonstrates exceptional sodium-storage performance in terms of high-rate capacities and long-duration cycle life in both half and full cells. Particularly, the TF-NCM@NTP-based quasi-solid-state NIBs deliver an applicable material-level energy density of 285 Wh kg^-1 at 25 °C, and exhibit wide-temperature-tolerant Na-storage behaviors ranging from -20 to 50 °C. More essentially, the multi-level engineering strategy from surface to bulk developed here definitely makes enormous progress for rationally designing advanced cathode materials toward multi-scenario applicable NIBs.