Exploring fluorinated electrolyte for high‐voltage and high‐safety Li‐ion cells with Li(Ni0.8Mn0.1Co0.1)O2 cathode

Conventional carbonate‐based electrolytes can be oxidized at voltages above 4.3 V, causing serious cell degradation, and are highly flammable that easily induces safety hazards. In this research, a non‐combustible electrolyte for high‐voltage Li(Ni0.8Mn0.1Co0.1)O2 cathode Li‐ion cells is investigated, using propylene carbonate (PC) and 2,2,2‐trifluoroethyl acetate (TFA) as solvents. The experimental results show that the electrolyte containing TFA can improve the cathode/electrolyte interface and mitigate side reactions so that the cells containing 1 M LiPF6 in PC/TFA (3:7, v/v) and the additionally added 2 wt.% of fluoroethylene carbonate (named PT37) exhibit a more advanced cycling performance and rate performance than those with the conventional electrolyte at high voltages (3.0‐4.5 V). Additionally, more competitive safety characteristics are revealed by PT37 cells through some typical safety evaluation tests involving the accelerating rate calorimetry test, nail test, and overcharge test. The results imply that a PT37 electrolyte is a hopeful option for high‐voltage and high‐safety Li‐ion cells.