Weakly solvated EC-free linear alkyl carbonate electrolytes for Ni-rich cathode in rechargeable lithium battery

Ethylene carbonate (EC) in the electrolyte is not stable in cells operated at high voltage (≥4.4V) or with Li metal anode, which greatly reduce the energy density and lifetime of the rechargeable lithium battery. Herein, an EC-free linear alkyl carbonate-based electrolyte is developed, which enables the high-voltage (≥4.4V) and low-temperature (-30°C) application of Ni-rich cathode (LiNi_0.8Mn_0.1Co_0.1O₂, NCM811). The EC-free system, consisting of LiPF₆ and LiNO₃ in ternary linear alkyl carbonates, possesses low viscosity, weakly solvated structure, and high interfacial stability with both the Ni-rich cathode and the Li metal anode to avoid continuous electrode/electrolyte side reactions and metal dissolution from the cathode. As a result, the Li||NCM811 cell delivers remarkable capacity retention of 93 ± 0.5% at the voltage of 4.4V and 88 ± 0.6% at 4.5V over 100 cycles. This study provides very encouraging perspective to develop EC-free carbonate-based electrolyte for high-voltage and low-temperature application in high-energy-density rechargeable lithium batteries.