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 degrees C) application of Ni-rich cathode (LiNi0.8Mn0.1Co0.1O2, 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 parallel to 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 appli-cation in high-energy-density rechargeable lithium batteries.

Automated summary

In this study, an EC-free carbonate-based electrolyte was developed to enable the high-voltage and low-temperature application of Ni-rich cathodes. The EC-free system has low viscosity, weakly solvated structure, and high interfacial stability with both the cathode and the anode.