Stalling CO2 evolution at high voltage by a catalytically induced LiF-rich interphase

Charging LiCoO₂ (LCO) to a higher voltage could increase deliverable capacity for higher energy density batteries while the catalytic activity of Cobalt (Co) is also rising, inevitably triggering electrolyte decomposition. Stable and robust cathode electrolyte interphase (CEI) is critical to creating physical isolation between cathode and electrolyte, hopefully relieving the interfacial side reaction including electrolyte decomposition. Here, we propose a catalytically induced strategy in yttrium-based interphase that selectively adsorbs PF₆^- for the preferential formation of LiF-rich CEI. Meanwhile, for bare LCO, we also reveal the uncontrolled decomposition of ethylene carbonate (EC) at high voltage, resulting in CO₂ release to seriously disorder CEI. Correspondingly, along with constructing a robust LiF-rich CEI and in turn inhibiting CO₂ release, the Y-modified LCO cathode exhibits a reversible capacity of 119 mAh g⁻¹ at 10 C and capacity retention of 93.12 % after 100 cycles at 1 C, which is much better than 62.30 % for the pristine LCO with serve electrolyte decomposition. This work unequivocally sheds light on the potential of interfacial modification to regulate the CEI chemistries in high-voltage batteries.