Explore Panasonic's flexible lithium-ion battery

The use scenario often encountered in card-type or wearable smart devices is that they need to be carried in a wallet or pocket, which requires the battery to withstand bending or twisting. Such equipment often requires the use of small thin flexible batteries, but the performance of such batteries is easily degraded after being bent or twisted, resulting in shortened equipment running time. In fact, in terms of flexible batteries, the following problems have always been technical obstacles that need to be overcome: 1) Today's lithium-ion battery materials themselves are not flexible, how to adapt the battery materials to this application scenario 2) When the battery is bent/twisted, how Maintain good contact between battery material particles and reduce contact resistance. 3) How to ensure that the battery does not leak when the battery is bent/twisted. 4) How to increase the active material load and the battery capacity. In January 2017, Panasonic exhibited their latest research results on flexible batteries at CES2017. The flexible batteries can withstand certain bending and twisting and meet the Japanese JIS standard (JISX6305- 1) It is equivalent to meeting a bending radius of R40mm, a twisting angle of ±15°/85.6mm, and a battery thickness of only 0.55mm. The main application areas are card-type devices or wearable devices. The most striking feature of the battery is that it can maintain its performance after being bent to a radius of 25mm and twisted by 25 degrees. As of September 2016, Panasonic has applied for 25 Japanese patents and 15 overseas patents for the flexible battery technology. Generally, after the battery is bent or twisted, it will have a great impact on the cycle life. However, Panasonic’s newly developed flexible battery overcomes this shortcoming. This is mainly due to Panasonic’s redesign of the flexible battery’s laminated electrode structure, in which the electrode electrode and outer layer design have been optimized to make it resistant to bending/ Distorted, but how to optimize it is still unclear. For example, the discharge capacity after repeated bending 1000 times or twisting 1000 times (torsion angle ±25°/100mm) can maintain 99% of the initial capacity. And after 1000 charge-discharge cycle tests, the charge-discharge cycle life is almost the same as that of a battery without bending/distortion, and the capacity retention rate reaches 80%. At present, with the rise of smart wearable devices, research on flexible batteries is receiving more and more attention. Although the performance of the three flexible batteries released by Panasonic looks quite good, it can be seen that the capacity of these three batteries is still very small, and the largest is only 60mAh, which cannot meet the operation of slightly larger smart portable or wearable devices. Time, this research field is still in the development and growth stage. With the continuous enhancement of the functions of modern portable smart devices or wearable devices, battery consumption has always been a challenge to be faced. For example, the battery capacity of smart phones now has to be increased to 1000mAh, 2000mAh, 3000mAh, or even 4000mAh or higher Up. Therefore, to truly realize this new type of flexible lithium-ion battery technology, the most basic one is that it must have a capacity of several thousand mAh to ensure the running time of the device. More importantly, the performance cannot be degraded when the battery is subjected to mechanical deformation. Only in this way can we meet the numerous portable/wearable smart electronic devices today.