The LIB is a rechargeable battery that uses a nonaqueous electrolyte with carbon as the negative electrode and a metal oxide containing lithium ions as the positive electrode. Conventional rechargeable batteries such as nickel-metal hydride (NiMH), on the other hand, use an aqueous electrolyte, which prevents their cell voltage from rising above around 1.5 V, the voltage of the electrolysis of water.
The use of a nonaqueous electrolyte allowed the cell voltage of the LIB to be raised to 4.2 V—near the theoretical limit of 6 V. This major leap in cell voltage enabled the achievement of smaller size and lighter weight, as had long been sought in rechargeable battery research. The reduced size and weight of the LIB catalyzed the IT revolution which began around 1995, facilitating the rapid growth of the market for cell phones, laptop computers, and many other portable electronic products.
In 1981, my team began research on rechargeable battery systems using polyacetylene, an electroconductive polymer discovered by Dr. Hideki Shirakawa, who later won the Nobel Prize in Chemistry. We found that polyacetylene could be used as electrode material for a rechargeable battery, and focused our research on using polyacetylene as negative electrode material. At the time, many researchers were working with metallic lithium as negative electrode material, but were unable to successfully commercialize a rechargeable battery due to various problems associated with metallic lithium.
We were able to fabricate prototype rechargeable cells using polyacetylene as negative electrode material and LiCoO2 (lithium cobalt oxide) as positive electrode material. The photo at left shows the first such prototype we made, in 1983. We later switched from polyacetylene to carbon as negative electrode material, and in 1985 we succeeded in developing the LIB as we know it today.
The LIB literally provided the juice that powered the IT revolution that has transformed the way we live and work. As a powerful, small, light rechargeable battery, it made possible the rapid market growth for portable electronic products with ever greater features and functions. Even as the further advancement and growth of small, portable products continues, the LIB has begun to find uses in medium-sized and large battery applications. Most notable among these is in transportation, for hybrid electric and all-electric vehicles. Another application which is on the verge of taking off is in storage batteries that provide electric power for homes.
Such larger-scale applications for the LIB are gaining momentum as key elements in the world-wide effort to deal with environmental challenges and advance resource and energy conservation. Further technological development of the LIB is now advancing to provide the performance characteristics required in these new applications. In another fifteen years or so, around 2025, I believe the LIB will be used in ways we cannot even imagine today.