LiFeO₂-Incorporated Li₂MoO₃ as a Cathode Additive for Lithium-Ion Battery Safety

Abstract

Li2MoO3, with a Mo(IV)/Mo(VI) redox couple, has been tested as a cathode additive to make lithium-ion batteries safe under abnormal discharge conditions. Its high charging capacity and sloping discharge voltage below 3.4 V vs Li+/Li effectively prevents the Cu anode current collector from oxidative dissolution at the overdischarge condition. However, molybdenum dissolution from the electrochemically charged Li2MoO3 quickly deteriorates the battery performance at 45 °C. A solid solution of Li2MoO3 with LiFeO2 has stabilized the crystalline structure at the charged states and suppressed the Mo(VI) dissolution. The addition of 10 wt % 0.9Li2MoO3–0.1LiFeO2 to LiCoO2 electrode enables long-term, high-temperature cycling in the operating voltage range of 0.0–4.3 V vs graphite.