Polymer Molecular Engineering Enables Rapid Electron/Ion Transport in Ultra-Thick Electrode for High-Energy-Density Flexible Lithium-Ion Battery

Flexible lithium-ion batteries (LIBs) with high energy density are of urgent need for the ever-increasing flexible and wearable electronic equipments, but limited by the low areal loading of active materials in traditional electrodes with lamellar structure. It is still a great challenge to solve the sluggish electron/ion transport problem caused by increasing the areal loading of active materials. Herein, a kind of ethylene vinyl acetate copolymer (EVA) is proposed to provide flexible supports and ion channels for ultra-thick flexible LFP/CNT/EVA cathode and LTO/CNT/EVA anode, thereby achieving high energy density and all flexible LIBs. LFP/CNT/EVA shows a ternary homogeneous structure formed by the entanglement of EVA chains and CNT on LFP, which attributes to LFP content up to 80wt% and adjustable thickness from 20 to 460 mu m. In sharp contrast to previous studies LFP/CNT/EVA delivers basically the constant specific capacity of approximate to 160 mAh g(-1) at a 0.1 C rate with the thickness increasing, thus achieving ultrahigh areal capacity up to 4.56 mAh cm(-2). A flexible full LIBs based on LFP/CNT/EVA and LTO/CNT/EVA is demonstrated and exhibits favorable cycle performance under an alternant flat and bending state. Those findings are supposed to open new avenues for designing high-energy-density flexible LIBs for future wearable energy storage devices.

Automated summary

By using ethylene vinyl acetate copolymer (EVA) as flexible supports and ion channels, high-energy-density flexible LFP/CNT/EVA cathode and LTO/CNT/EVA anode are successfully prepared, achieving high energy density and all flexible LIBs. The system is able to maintain a constant specific capacity while increasing thickness, resulting in ultrahigh areal capacity.