Vinylene carbonate and Li salicylatoborate as additives in LiPF₃(CF₂CF₃)₃ solutions for rechargeable Li-ion batteries

Merck KGaA developed LiPF₃(CF₂CF₃)₃, (LiFAP) as a new electrolyte that can replace the commonly used LiPF₆ in Li-ion batteries. Vinylene carbonate and Li salicylato borate (Merck's AD25) were studied as additives for LiFAP solutions in mixtures of ethylene, dimethyl, and diethyl carbonates with composite graphite and LiMn₂O₄ electrodes. The tools for this study included voltammetry (fast and slow scan rates), chronopotentiometry, impedance spectroscopy, electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. It was found that LiFAP solutions containing VC were superior for both graphite and LiMn₂O₄ (spinel) electrodes. The effect of additives on the electrodes' performance can be clearly attributed to their impact on the surface chemistry of these electrodes.