1. Successful Development of a Highly Safe Lithium-ion Battery Prototype Using a New, Hardly Combustible Electrolyte
To improve the safety of battery systems while also making them smaller and less expensive, Hitachi has developed a prototype rechargeable lithium-ion battery (LIB) that uses a new hardly combustible electrolyte. LIBs have a wide range of applications, not only in portable devices but also as power sources for electric vehicles and renewable energy power conditioners. A problem with past LIBs, however, is that their use of liquid electrolytes with a flash point temperature of less than 20°C made them prone to catching fire in case of accidents.
Hitachi has worked with Tohoku University on the development of electrolytes with flash points of more than 100°C greater than the conventional liquid electrolyte currently used in LIBs, using lithium conductivity simulations to successfully develop a new electrolyte possessing high lithium ion conductivity. The new electrolyte was used to assemble a prototype laminated battery with a 100-Wh capacity and a nail penetration test was conducted to verify its safety. The results demonstrated that the battery was less prone to heating and causing thermal runaway in the event of an internal short circuit accompanied by nail penetration. It was concluded from this work that the battery has the potential to make systems smaller and more price-competitive by allowing system designs to reduce and simplify the reinforcing material and cooling systems incorporated into past battery systems to ensure their safety.