Sheet-like Rechargeable Battery Developed Using New Principle (3)

Mar 2, 2014
Kouji Kariatsumari & Tsunenori Tomioka, Nikkei Technology Online

Continued from Sheet-like Rechargeable Battery Developed Using New Principle (2)

Nevertheless, the "battenice" rechargeable battery has many advantages over Li-ion rechargeable batteries. For example, it has a very high output density, does not cause liquid leakage or fire (due to thermal runaway), eliminates concern about material procurement, has a long cycle life, etc.

With those advantages, it is considered possible to effectively use the new battery in ways different from the ways in which Li-ion batteries are used. Therefore, we expect that they will be used not only as normal batteries by stacking several sheets but also for wearable devices and as batteries on printed circuit boards (PCBs) or combined with a thin-film solar cell, forming a new market with its flexibility.

In addition to the aforementioned prototype, Micronics Japan has already made (1) a sheet-like battery (with a battery layer formed only on one side) whose area is 300 x 300mm and thickness is 11μm and (2) a battery consisting of 32 sheets, each of which has an area of 100 x 100mm and thickness of 11μm (with a battery layer formed only on one side). The company is planning to ship samples for application development within 2014.

Though Micronics Japan has not disclosed the manufacturing process of the new battery, according to a patent that Guala Technology applied for (WO2012046325A1), the battery might have been made in the following way.

First, negative electrodes (indium oxide doped with tin or ITO) and n-type metal oxide semiconductor layer (TiO2) are formed on a substrate by sputtering. Then, fatty acid titanium, silicone oil and solvent are mixed and stirred, and the TiO2 layer is spin-coated with it. It is dried at a temperature of 50°C for 10 minutes and calcinated at a temperature of 300-400°C for 10 to 60 minutes.

As a result, the fatty acid titanium is decomposed, forming a TiO2 particulate layer coated with silicone. When an ultraviolet light with a wavelength of 254nm is applied to it with an intensity of 20mW/cm2 for about 40 minutes, a number of new energy levels, which contribute to charge and discharge of the battery, are formed in the bandgap of TiO2. The p-type metal oxide semiconductor (NiO) and positive electrodes are formed by sputtering.

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