All new solid air rechargeable battery

In a new study published May 2, 2023 in the journal International edition of applied chemistry A group of Japanese researchers developed a rechargeable solid-state air battery (SSAB) and studied its capacity and durability. The study was led by Professor Kenji Miyatake of Waseda University and Yamanashi University and co-authored by Professor Kenichi Oyazu of Waseda University.

The researchers chose a chemical called 2,5-dihydroxy-1,4-benzoquinone (DHBQ) and its polymer, poly(2,5-dihydroxy-1,4-benzoquinone-3,6-methylene) (PDBM) as active materials for the negative electrode because of its reactivity. Stable and reversible redox under acidic conditions. In addition, they used a proton-conducting polymer called Nafion as the solid electrolyte, replacing traditional liquid electrolytes. “As far as I know, air batteries based on organic electrodes and solid polymer electrolytes have not yet been developed,” says Miyatake.

After installing the SSAB, the researchers experimentally examined the charge and discharge performance, performance characteristics, and rotability. They found that SSAB does not degrade in the presence of water and oxygen, unlike typical air batteries that use a metal negative electrode and a liquid organic electrolyte. In addition, a better negative electrode was formed by replacing the redox-active molecule DHBQ with its polymeric counterpart PDBM. While the discharge capacity per gram of SSAB-DHBQ was 29.7 mA, the corresponding value for SSAB-PDBM was 176.1 mA, with a constant current density of 1 ^{cubic meters -2}.

The researchers also found that the Coulombic efficiency of SSAB-PDBM at 4 °C was 84%, i.e. at 101^{C gradually decreased to 66%. While the discharge capacity of SSAB-PDBM decreased to 44% after 30 cycles, the researchers were able to significantly improve it to 78% by increasing the content of the proton-conducting polymer in the cathode. Electron micrographs confirmed that the addition of Nafion improved the performance and durability of the PDBM-based electrode.}

This study demonstrates the successful operation of an SSAB comprising redox-active organic molecules as the negative electrode, a proton-conducting polymer as the solid electrolyte, and an oxygen-reducing diffusion-type positive electrode. The researchers hope that this technology will pave the way for further advances. “This technology can extend the battery life of small electronic devices such as smartphones, and ultimately contribute to achieving a carbon-neutral society,” concludes Miyatake.