Green Science Alliance Doubles Aluminum Battery Capacity to 210 mAh/g

Green Science Alliance has more than doubled the performance of its aqueous aluminum-ion battery, reaching an initial capacity of at least 210 milliamp-hours per gram after replacing its cathode current collector with a commercially available conductive carbon rubber sheet, up from roughly 103 milliamp-hours per gram in earlier versions. The improved cell held that capacity for at least 25 cycles in ongoing testing at room temperature, developed by Dr. Ryohei Mori, who first published the underlying aqueous aluminum battery concept in a 2025 review in the Royal Society of Chemistry's Energy Advances. The breakthrough targets a battery chemistry with a theoretical energy density around 1,060 watt-hours per kilogram, more than double the 300 to 400 watt-hours per kilogram ceiling of conventional lithium-ion cells, while avoiding the scarce metals and flammability risks associated with lithium-based storage.

 

A Porous Current Collector Solves a Long-Standing Stability Problem

 

Aqueous aluminum-ion batteries have struggled to match their theoretical promise because earlier designs using dense carbon plates as the cathode current collector produced weak and unstable capacity. Mori's team found that switching to a porous conductive carbon rubber sheet allowed the cathode active material to penetrate the material's pores and form a three-dimensional composite structure, maintaining electrical pathways while letting the aqueous electrolyte reach deeper into the electrode and increase the surface area available for reaction. Cyclic voltammetry testing confirmed consistent charge-discharge redox peaks below the 1.23-volt threshold at which water electrolysis would otherwise interfere with the cell, with those peaks still detectable after 100 cycles.

The porous rubber sheet carries a second benefit beyond performance: because it is itself electrically conductive, it functions simultaneously as both current collector and part of the cathode's active material, a dual role that dense carbon plates could not provide. That structural simplification is what allowed the team to avoid a persistent cost problem in the sector, since earlier ionic-liquid-based aluminum battery designs required expensive corrosion-resistant metals such as molybdenum, niobium and tantalum for their current collectors to survive highly corrosive electrolytes.

 

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Avoiding Scarce Metals Addresses a Core Battery Supply Constraint

 

The appeal of aluminum as a battery material lies in its abundance and chemical stability. Unlike lithium, cobalt and nickel, which face documented supply concentration and extraction concerns, aluminum is one of the most common metals in the Earth's crust and remains chemically stable in air, reducing both raw material risk and the safety hazards tied to flammable lithium-ion electrolytes. Mori's aqueous approach compounds that advantage by replacing the corrosive, moisture-sensitive ionic liquid electrolytes used in earlier aluminum-ion designs with a water-based aluminum perchlorate solution, removing the need to assemble cells in inert nitrogen or argon atmospheres.

That combination directly targets the two constraints that have limited aluminum-ion batteries commercially: the need for expensive corrosion-resistant hardware and the manufacturing complexity of moisture-free assembly. With both addressed, the remaining technical barrier is the cell's operating voltage of 0.9 to 1.0 volts, lower than a standard lithium-ion cell, though Mori notes this can be offset by connecting multiple cells in series, a standard battery engineering approach used across other chemistries.

 

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Cost Projections Undercut Lithium-Ion by More Than Half

 

Cost estimates cited alongside the research place current lithium-ion battery production around $115 per kilowatt-hour, while aluminum-ion batteries using ionic liquid electrolytes are projected to fall to between $55 and $60 per kilowatt-hour at scale. Because the aqueous design eliminates the need for both inert-atmosphere assembly and expensive corrosion-resistant current collectors, Green Science Alliance expects its version to undercut even that lower figure once manufacturing is scaled, using inexpensive components including graphite as the cathode active material and ordinary paper as the separator.

Part of the results will be presented at the 250th meeting of the Electrochemical Society in Calgary, Canada, in October 2026, where Mori's team plans to share the findings with the broader battery research community. The next phase of work is aimed squarely at the two metrics that still separate a laboratory result from an industrial product, extending the cycle count well beyond the 25 cycles demonstrated so far and further raising capacity toward the chemistry's theoretical ceiling, since a battery destined for grid storage or other commercial applications will need to sustain performance over hundreds or thousands of charge cycles rather than dozens.