Various research teams are experimenting with aluminium to produce better batteries. Requirements include cost, durability, capacity, charging speed, and safety.
Anode Cornell University In 2021, researchers announced a cell that used a 3D structured anode in which layers of aluminium accumulate evenly on an interwoven carbon fiber structure via covalent bonding as the battery is charged. The thicker anode features faster kinetics, and the prototype operated for 10k cycles without signs of failure.
Electrolyte Oak Ridge National Laboratory Around 2010, ORNL used an ionic electrolyte, instead of the typical aqueous electrolyte which can produce
hydrogen gas and corrode the anode. The electrolyte was made of
3-ethyl-1-methylimidazolium chloride with excess
aluminium trichloride. However, ionic electrolytes are less conductive, reducing power density. Reducing anode/cathode separation can offset the limited conductivity, but causes heating. ORNL devised a cathode made up of
spinel manganese oxide that further reduced corrosion. Vanadium oxide has an open crystal structure with greater surface area and reduced path between cathode and anode. The device produced a large output voltage. However, the battery had a low
coulombic efficiency. The prototype lasted over 7,500 charge-discharge cycles with no loss of capacity. The battery was made of an aluminium anode, liquid electrolyte, isolation foam, and a
graphite cathode. During the charging process,
AlCl4− ions intercalate among the
graphene stacked layers. While discharging, AlCl4− ions rapidly de-intercalate through the graphite. The cell displayed high durability, withstanding more than 10,000 cycles without a capacity decay. The cell was stable, nontoxic, bendable and nonflammable. In 2016, the lab tested these cells through collaborating with Taiwan's
Industrial Technology Research Institute (ITRI) to power a motorbike using an expensive electrolyte. In 2017, a
urea-based
electrolyte was tested that was about 1% of the cost of the 2015 model. The battery exhibits ~99.7% Coulombic efficiency and a rate capability of 100 mA/g at a cathode capacity of 73 mAh/g (1.4 C).
ALION Project In June 2015, the High Specific Energy Aluminium-Ion Rechargeable Batteries for Decentralized Electricity Generation Sources (ALION) project was launched by a consortium of materials and component manufacturers and battery assemblers as a European
Horizon 2020 project led by the LEITAT
research institute. The project objective is to develop a prototype Al-ion battery that could be used for large-scale storage from decentralized sources. The project sought to achieve an
energy density of 400 Wh/kg, a voltage of 48 volts and a charge-discharge life of 3000 cycles. 3D printing of the battery packs allowed for large Al-ion cells developed, with voltages ranging from 6 to 72 volts.
University Of Maryland In 2016, a University of Maryland team reported an aluminium/sulfur battery that utilizes a sulfur/carbon composite as the cathode. The chemistry provides a theoretical energy density of 1340 Wh/kg. The prototype cell demonstrated energy density of 800 Wh/kg for over 20 cycles.
MIT In 2022, MIT researches reported a design that used cheap and nonflammable ingredients, including an aluminium anode and a sulfur cathode, separated by a molten chloro-aluminate salt electrolyte. The prototype withstood hundreds of charge cycles, and charged quickly. They can operate at temperatures of up to . At , the batteries charged 25 times faster than at . This temperature can be maintained by the charge/discharge cycle. The salt has a low melting point and prevents dendrite formation. One potential application is at charging stations, where a pre-charged battery could allow the station to charge more vehicles simultaneously without a costly upgrade to the power line. Spinoff company Avanti, co-founded by one of the researchers, is attempting to commercialize the work.
Queensland University of Technology In 2019 researchers from
Queensland University of Technology developed
cryptomelane based electrodes as cathode for aluminium ion battery with an aqueous electrolyte.
Clemson University In 2017, researchers at
Clemson Nanomaterials Institute used a graphene electrode to intercalate tetrachloroaluminate ().
Zhejiang University In December 2017 a
Zhejiang University team announced a battery using graphene films as cathode and metallic aluminium as anode. The 3H3C (Trihigh Tricontinuous) design results in a graphene film cathode with excellent electrochemical properties.
Liquid crystal graphene formed a highly oriented structure. High-temperature
annealing under pressure produced a high-quality and high-channelling graphene structure. Claimed properties: • Retained 91.7 percent of original capacity after 250,000 cycles. • 1.1-second charge time. • Temperature range: −40 to 120 °C • Current capacity: 111 mAh/g, 400 A/g • Bendable and non-flammable. • Low energy density
Redox battery Another approach to an aluminium battery is to use
redox reactions to charge and discharge. The charging process converts
aluminium oxide or
aluminium hydroxide into ionic aluminium using
electrolysis, typically at an
aluminium smelter. This requires temperatures of . One report estimated possible efficiency at around 65%. Although ionic aluminium oxidizes in the presence of air, this costs less than 1% of the energy storage capacity. Discharging the battery involves oxidizing the aluminium, typically with water at temperatures less than 100 °C. This yields aluminium hydroxide and ionic hydrogen. The latter can produce electricity via a
fuel cell. The oxidation in the fuel cell generates heat, which can support space or water heating. A higher-temperature process could support industrial applications. It operates at over 200 °C, reacting aluminium with steam to generate aluminium oxide, hydrogen and additional heat. The ionic aluminium could be stored at the smelter. One approach charges the battery at a smelter, and discharges it wherever power and heat are needed. Alternatively, electricity could be fed into the grid at the smelter, without the need for transport, although for maximum round-trip efficiency, the heat would have to be used at the smelter site. == See also ==