Flexible See-Through Battery Power

Dr. Hiroyuki Nishide, Dr. Hiroaki Konishi and Dr. Takeo Suga at the Waseda University in Japan have designed a clear plastic battery consisting of a redox-active organic polymer film around 200 nanometers thick. Nitroxide radical groups are attached, acting as charge carriers. Due to its high radical density, the battery has a high charge/discharge capacity. According to the researchers, this is one of many advantages the “organic radical” battery has over other organic-based materials. The power rate is strikingly high – it only takes one minute to fully charge the battery and it has a long cycle life, often exceeding 1,000 cycles.

The team made the thin polymer film by a solution-processable method – a soluble polymer with the radical groups attached is “spin-coated” onto a surface. After UV irradiation, the polymer then becomes crosslinked with the help of a bisazide crosslinking agent. A drawback of some organic radical polymers is that they are soluble in the electrolyte solution which results in self-discharging of the battery – but the polymer must be soluble so it can be spin-coated. However, the photocrosslinking method used by the Japanese team overcomes the problem and makes the polymer mechanically tough. “This has been a challenging step, since most crosslinking reactions are sensitive to the nitroxide radical,” says Nishide.

Professor Peter Skabara, an expert in electroactive materials at the University of Strathclyde , praised the high stability and fabrication strategy of the polymer-based battery. “The plastic battery plays a part in ensuring that organic device technologies can function in thin film and flexible form as a complete package.”

This was reported in The Royal Society of Chemistry journal Chemical Communications.