Enabling the High-Voltage Operation of Layered Ternary Oxide Cathodes via Thermally Tailored Interphase.

Layered ternary oxides LiNi x Mn y Co z O 2 are promising cathode candidates for high-energy lithium-ion batteries (LIBs), but they usually suffer from the severe interfacial parasitic reactions at voltages above 4.3 V versus Li + /Li, which greatly limit their practical capacities. Herein, using LiNi 1/3 Mn 1/3 Co 1/3 O 2 (NMC111) as the model system, a novel high-temperature pre-cycling strategy is proposed to realize its stable cycling in 3.0-4.5 V by constructing a robust cathode/electrolyte interphase (CEI). Specifically, performing the first five cycles of NMC111 at 55 °C helps to yield a uniform CEI layer enriched with fluorine-containing species, Li 2 CO 3 and poly(CO 3 ), which greatly suppresses the detrimental side reactions during extended cycling at 25 °C, endowing the cell with a capacity retention of 92.3% at 1C after 300 cycles, far surpassing 62.0% for the control sample without the thermally tailored CEI. This work highlights the critical role of temperature on manipulating the interfacial properties of cathode materials, opening a new avenue for developing high-voltage cathodes for Li-ion batteries.