High Energy Density Flexible Battery with Self-Standing Binder- and Collector-Free Electrodes

Abstract

Rapid development and miniaturization of portable and wearable electronic require compact powering devices with highest possible energy density combined with mechanical flexibility. Li-ion batteries remain most practical energy storage devices. Their energy density can be increased by removing electrochemically dead components such as metal collector foils, binder and additives. We developed novel self-standing collector-, and binder-free electrodes produced by a mixing of battery active materials with as-grown carbon nanotubes in a gas-phase. Resulted composite sheets consisting of the particles of the active material imbedded in the 3-dimentional network of pristine carbon nanotubes. The method allow exploiting particles/flakes of any active materials. Electrodes grown by this method can be up to 2 mm thick and have up to 25 mAh/cm2 areal capacity density (in case of NMC 5:2:3 active cathode material). Electrodes are flexible and stretchable in a wide range of compositions, allowing fabrication of flexible battery cells. Since metal collector foils are not present, the electrodes are naturally two-sided, simplifying manufacturing of stacked cells. Batteries that exploit the electrodes fabricated by this method can power flexible electronics.