Stretchable Rechargeable Lithium-Ion Batteries

Deformable, stretchable electronics are considered as next-generation devices; however, to realize highly flexible electronics, it is first necessary to develop a deformable energy device. Herein, a crumply and highly flexible lithium-ion battery is realized by using microfiber mat electrodes in which the microfibers are wound or webbed with conductive nanowires. This electrode architecture guarantees extraordinary mechanical durability without any increase in resistance after folding 1,000 times. Its areal energy density is easily controllable by the number of folded stacks of a piece of the electrode mat. Deformable lithium-ion batteries of lithium iron phosphate as cathode and lithium titanium oxide as anode at high areal capacity (3.2 mAh cm–2) are successfully operated without structural failure and performance loss, even after repeated crumpling and folding during charging and discharging. As another deformable batteries, we demonstrate the fabrication of highly stretchable hybrid carbon/polymer (HCP composite which was found to effectively retain its electrical conductivity, even when under high strain (~200%), due to the co-supporting network of hybrid nanofillers in its structure. We are the first to have developed a stretchable aqueous rechargeable lithium-ion battery (ARLB) that utilized this HCP composite as a stretchable current collector. The ARLB exhibited excellent rate capability (~90 mA h g−1 at a rate of 20 C) and outstanding durability (capacity retention of 93% after 500 cycles).1