No abstract

In an effort to create a truly flexible and wearable display having a flexible battery as well as a flexible organic light‐emitting diode panel and a flexible printed circuit, a flexible lithium‐ion battery has been developed, and a prototype wrist‐wearable or arm‐wearable display has been fabricated. Owing to improvements in the internal structure and exterior of the lithium‐ion battery, no remarkable changes in charge and discharge curves and the internal state of the electrodes were observed even after conducting a 10,000‐cycle bending test. Therefore, this flexible lithium‐ion battery prototype demonstrated remarkable bending resistance. Thus, we succeeded in fabricating a truly flexible and wearable display comprised of a flexible organic light‐emitting diode panel, a flexible printed circuit, and a flexible battery.

To fabricate a genuinely flexible and wearable display with a flexible battery together with a flexible OLED panel and a flexible printed circuit, a flexible lithium ion battery has been developed, and a prototype of a wrist-wearable display has been fabricated.

A flame-and heat-resistant lithium-ion battery (LIB) has been developed using ionic liquid electrolyte. This battery can be stably discharged at 100°C as well as at 0°C. A heat-resistant organic light-emitting diode (OLED) using this battery as a power source has been stably operated at temperatures of 100°C and 0°C.

A promising Si negative electrode, that is a well controlled array of Si nanopillar, was fabricated by a semiconductor process. The electrochemical property of this electrode was examined by charge-discharge measurements, SEM and TEM observations. Although the result of charge-discharge measurements of this Si nanopillar electrode was comparable to those of a flat thin film Si electrode, pulverization of the Si film was successfully suppressed in the Si nanopillar electrode. In the Si thin film electrode, only the upper half of the Si film seemed to have reacted, and this caused cracking and pulverization. By contrast, in the Si nanopillar electrode, the entire Si film seemed to have reacted, and cracking and pulverization were suppressed. The experimental results demonstrated that the Si nanopillar electrode has a suitable structure for a Si negative electrode.