All-dry solid-phase synthesis of single-crystalline Ni-rich ternary cathodes for lithium-ion batteries

Single-crystalline ternary cathodes prepared through all-dry solid-phase synthesis (ADSPS) are perceived as prominent candidates for lithium-ion batteries (LIBs) because they are inexpensive and effluent-free. However, the aggravated lithium/oxygen (Li/O) loss and sluggish lithiation process during sintering result in an unstable layered structure and a large amount of surface residual alkali. Herein, a lithium borate (LBO)-coated and strontium/titanium (Sr/Ti) co-doped single-crystalline nickel (Ni)-rich ternary cathode with a highly ordered layered structure is prepared via ADSPS for the first time. The synergistic effect of Sr/Ti ions considerably promotes grain growth with decreased lithiation temperature, which alleviates the Li/Ni disorder and stabilizes the lattice O. After coating with a layer of LBO, the surface residual alkali has been considerably depleted with favorable Li-ion transfer at the interface. Consequently, the as-obtained cathode delivers a high reversible capacity of 191.1 mA h g−1 at 0.1 C in coin-type half cells and superior retention of 90.1% after 500 cycles at 1 C in pouch-type full cells. The unique insight and strategy in this research will promote the application of ADSPS in single-crystalline Ni-rich ternary cathodes for LIBs.