A Chinese research team has developed a neutral-electrolyte aqueous battery with a lifespan 10 times longer than existing products.

Gigazine, an online media outlet, reported on May 8 that the battery could withstand about 120,000 charge-discharge cycles. It said this suggests a potential lifespan of several centuries in power-grid energy storage systems.

Aqueous batteries use water-based solutions as electrolytes. They are seen as having a lower fire risk than lithium-ion batteries. But conventional aqueous batteries mainly use acidic or alkaline electrolytes, leading to oxygen-evolution or hydrogen-evolution reactions during charging and discharging. That process rapidly consumes water and limits lifespan. Critics have also pointed to the environmental burden of strongly acidic or strongly alkaline solutions at the disposal stage.

Researchers at City University of Hong Kong designed a material combination with slower degradation and lower environmental harm to reduce those limits. The team synthesised a covalent organic polymer as the anode material. It combined it with electrolytes based on magnesium and calcium salts that are close to neutral to make an aqueous battery.

The key is the combination of an organic polymer and a neutral electrolyte. Such organic polymers generally decompose quickly in strongly acidic or strongly alkaline electrolytes, so they have not been widely used in conventional aqueous batteries. The researchers avoided this by applying a neutral electrolyte. They explained that the electrolyte they used is so environmentally friendly that it could even be used as "nigari", the bittern used in tofu production.

The lifespan figure also stands out. The organic polymer developed by the researchers was presented as being able to withstand 120,000 charge-discharge cycles. That is more than 10 times the lifespan of typical lithium-ion batteries. An explanation cited by the outlet said grid storage batteries in 2024 were operated at an average of 1.1 cycles per day, and at that rate the new aqueous battery could potentially be used for about 300 years before replacement.

The researchers stressed the result as progress in developing anode materials compatible with neutral electrolytes. "This research result shows major progress in developing anode materials suitable for neutral electrolytes," the team said. It added that it could provide energy storage solutions that are safer, high-performance, long-life and environmentally considerate.

The limitations are also clear. The battery has a limited maximum voltage and cannot store as much energy as existing lithium-ion or sodium-ion batteries. It is likely to be considered first in fields where safety and lifespan matter more than in portable devices or high energy-density applications.

Against that backdrop, the research is meaningful in that it pointed to a direction that reduces both the short lifespan and disposal burden cited as weaknesses of aqueous batteries. But whether real-world use expands depends on how much it can address the limitation of low energy storage.