Artificial Electrode Interface Enables Stable Operation of Freestanding Anodes for High-Performance Flexible Lithium Ion Batteries
High-performance flexible lithium-ion batteries are leading candidates as power sources of wearable and foldable electronics. As a result, it is vital to design freestanding electrodes with high capacity and stability. Herein, we develop a novel strategy to significantly improve the performance of freestanding electrodes by artificially introducing an ultrathin but robust interface based on polyacrylamide/gelatin gel with excellent mechanical durability and ionic conductivity. The artificial interface suppresses the formation of a thick solid electrolyte interface, facilitates charge transfer processes and strengthens the integrity of the electrode. Benefited from these merits, our freestanding anode made of nano/microstructured NiFe2O4-CNTs composite reaches a high capacity of 612 mAh g-1 based on the total mass of the electrode, which further enables a stable output capacity of 140 mAh g-1 over 1000 charge/discharge cycles for a full battery using commercial LiMn2O4 as the cathode material. Meanwhile, excellent rate performance of the freestanding anode guarantees high energy output up to 255 Wh kg-1 at a high power density of 12000 W kg-1 for the full battery. Moreover, the intrinsic flexibility of the freestanding electrodes enables the fabrication of a flexible lithium-ion battery, which performances highly stable even under harsh mechanical deformation. This work guides a new perspective to fabricate next-generation flexible batteries with high energy density and excellent stability, further advancing the development of foldable and wearable electronics toward practical applications.