An ultrafast rechargeable aluminium-ion battery

An aluminium-ion battery is reported that can charge within one minute, and offers improved cycle life compared to previous devices; it operates through the electrochemical deposition and dissolution of aluminium at the anode, and the intercalation/de-intercalation of chloroaluminate anions into a novel graphitic-foam cathode. The low cost and useful electrical properties of aluminium suggest that rechargeable Al-ion batteries could offer viable and safe battery technology, but problems with cathode materials, poor cycling performance and other complications have persisted. Here Hongjie Dai and colleagues describe an Al-ion battery that can charge within one minute and offers substantially improved cycle life with little decay in capacity compared to previous devices reported in the literature. The battery operates through the electrochemical deposition and dissolution of Al and intercalation/de-intercalation of chloroaluminate anions into a novel 3D graphitic foam cathode using a non-flammable ionic liquid electrolyte. The development of new rechargeable battery systems could fuel various energy applications, from personal electronics to grid storage1,2. Rechargeable aluminium-based batteries offer the possibilities of low cost and low flammability, together with three-electron-redox properties leading to high capacity3. However, research efforts over the past 30 years have encountered numerous problems, such as cathode material disintegration4, low cell discharge voltage (about 0.55 volts; ref. 5), capacitive behaviour without discharge voltage plateaus (1.1–0.2 volts6 or 1.8–0.8 volts7) and insufficient cycle life (less than 100 cycles) with rapid capacity decay (by 26–85 per cent over 100 cycles)4,5,6,7. Here we present a rechargeable aluminium battery with high-rate capability that uses an aluminium metal anode and a three-dimensional graphitic-foam cathode. The battery operates through the electrochemical deposition and dissolution of aluminium at the anode, and intercalation/de-intercalation of chloroaluminate anions in the graphite, using a non-flammable ionic liquid electrolyte. The cell exhibits well-defined discharge voltage plateaus near 2 volts, a specific capacity of about 70 mA h g–1 and a Coulombic efficiency of approximately 98 per cent. The cathode was found to enable fast anion diffusion and intercalation, affording charging times of around one minute with a current density of ~4,000 mA g–1 (equivalent to ~3,000 W kg–1), and to withstand more than 7,500 cycles without capacity decay.