A liquid e-fuel cell operating at −20 °C

An electrically rechargeable liquid fuel (e-fuel) system, which comprises an e-fuel charger and an e-fuel cell, has recently been proposed and proven as an effective approach for storing renewable energy. Potential e-fuels are stated to be obtainable from various electroactive materials including metal ions. In this work, a liquid e-fuel made of vanadium ions for anodic reaction is introduced. Utilizing this e-fuel paired with oxygen at the cathode side, the operation of a liquid e-fuel cell, capable of generating electricity stably at sub-zero cell temperature as low as −20 °C, without involving any form of internal or external heating system is demonstrated. At −20 °C, this liquid e-fuel cell demonstrates a peak power density of 76.8 mW cm⁻² and an energy efficiency of 25.2% at 30 mA cm⁻², which outperforms all the conventional direct liquid alcohol fuel cells operating under sub-zero environment and even at room temperatures. The successful operation of this e-fuel cell, with its competence and impressive performance at sub-zero temperatures, even at the first time of its demonstration, opens a significant window of opportunity towards the advancement of fuel cell technology, particularly for energizing future fuel cell electric vehicles with an all-climate operation.