Lithium-ion battery and its evolution
Winner of the European Inventor Award 2019
Rechargeable batteries in the 1980s had proven too bulky and expensive to power electronic devices such as computers. Researchers started developing lighter lithium-based alternatives, but they often exploded or caught fire.
In 1983, Professor Akira Yoshino filed a patent application for the lithium-ion battery as we know it today, taking the original concept and modifying it to be safe, efficient and reliable. He replaced the unstable lithium metal at its anode with a safe electrically-conductive plastic known as polyacetylene. He swapped the battery cathode material for lithium cobalt oxide - a more stable alloy that had just been discovered. He also introduced a heat sensitive membrane based on polyethylene between reactive layers. When the battery overheated, the membrane would melt and act like a fuse to stop the whole structure from catching fire. This was the first lithium-ion battery design to reach shelves and power consumer electronics. In subsequent years, Yoshino refined his creation and invented a battery that could sustain more charging and discharging cycles. He later boosted the voltage of lithium-ion batteries from 1.5 volts to over 4 volts by adapting the structure and composition of the anode.
Patents have helped to protect these solutions and today, Yoshino is named as inventor on 56 Japanese and 6 European patents. Asahi Kasei, the company for which Yoshino has worked since the 19070s, had 17% of the global market share for lithium-ion battery separators up to 2016. The worldwide market for lithium-ion batteries was estimated at EUR 26.5 billion in 2017 and projected to reach over EUR 80 billion by the year 2025.
Yoshino is passionate about science and mathematics. He studied petrochemistry at Kyoto University and holds a PhD in engineering from Osaka University. He also heads Japan's Lithium Ion Battery Technology and Evaluation Centre. At the age of 71, Yoshino continues his work at Asahi Kasei to boost the safety and efficiency of lithium-ion batteries.
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