Current zinc-based batteries often have relatively short lifespans because their materials gradually degrade during repeated charge-discharge cycles.

By changing the chemistry of the battery’s cathode, Chinese researchers have developed a new liquid zinc-ion battery that retains nearly 90 percent of its capacity even after more than 10,000 charge-discharge cycles.

According to the team, this corresponds to more than 3,500 hours of continuous operation.

The researchers said their strategy could help pave the way for designing longer-lasting aqueous energy storage systems.

Existing aqueous zinc-ion batteries (ZIBs) typically rely on iodine-based cathodes because they offer long cycling stability, fast charge-discharge capability, and the potential to store large amounts of energy.

However, iodine-based cathodes also suffer from several limitations. They conduct electricity poorly, undergo structural changes as the battery charges and discharges, and allow iodine ions to migrate through the battery. This so-called shuttle effect reduces efficiency, accelerates material degradation, and shortens battery life.

To overcome these challenges, researchers from Jilin University and the Changchun Institute of Applied Chemistry modified the functional group chemistry of the cathode to develop self-supporting carbon nanotube cathodes (SSCC).

In their experiments, they compared the iodine adsorption capability of modified carbon nanotubes with that of unmodified ones. The team investigated nanotubes functionalized with hydroxyl (‒OH), carboxyl (‒COOH), and amine (‒NH₂) groups to determine which surface chemistry performed best.

Using spectroscopy and microscopy techniques, the researchers confirmed the successful introduction of the functional groups and the uniform loading of iodine throughout the cathode material.

They found that the hydroxyl-modified nanotubes acted like tiny anchors, trapping iodine ions where they belonged rather than letting them migrate through the battery.

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