New water battery lasts 120,000 cycles

Researchers from the City University of Hong Kong and Southern University of Science and Technology have developed a new type of environmentally friendly aqueous battery that could become an alternative to traditional lithium-ion systems. Conventional batteries use aggressive acids and bases that corrode internal materials over time and pose a serious environmental risk if improperly disposed of. The new design avoids this altogether.

Instead of toxic electrolytes, the battery uses a neutral solution of magnesium and calcium salts, similar to those used in making tofu. The electrolyte has a pH of 7, meaning it does not corrode the electrodes and allows for a significantly longer lifespan.

The negative electrode is based on a specially synthesized organic polymer that acts as a highly conductive plastic network. Its chemical bonds allow for rapid storage of divalent ions, which is crucial for stable operation. The positive electrode is made of Prussian blue, a well-known material in the world of aqueous batteries.

Testing has shown that the cell achieves a voltage of 2.2 V and a specific energy of 48.3 Wh/kg, with the most impressive data being its exceptional durability: the battery remained stable through 120,000 cycles at a high load of 20 A/g. If charged once a day, it would theoretically last for more than 300 years, which is incomparable to conventional batteries, which begin to fail after a few thousand cycles.

The system also achieves 112.8 mAh/g specific capacity, and the materials are completely non-toxic and compliant with international environmental standards such as RCRA and ISO 14001. This means they can be safely disposed of without special procedures.

Commercialization will require addressing challenges such as scaling up organic polymer production and improving energy density in a limited space, but the new technology points to a future of batteries that are safe, durable and environmentally friendly.