Oxygen-deficient Ta2O5 nanoporous films as self-supported electrodes for lithium microbatteries

Electrode architectures with large capacity and good stability are exceedingly desired but remain an intriguing challenge for energy storage applications such as on-chip integrated microbatteries, where there is a grand need for high-energy and high-power three-dimensional (3D) electrodes to replace the conventional planar electrodes. Here we report a highly efficient and durable lithium electrode based on 3D self-supported nanoporous tantalum pentoxide (Ta2O5) film. The Ta2O5 film is prepared by electrochemically anodizing tantalum metal in ammonium fluoride electrolyte and subsequent thermal annealing at 450 degrees C in argon atmosphere, which does not crystallize the film but gives rise to significant amount of oxygen deficiency. The Ta2O5 film exhibits a high lithium capacity of similar to 480 mAh g(-1) and remarkable cycling stability over 8000 cycles at a rate of 5 C, which could be attributed to improved transport kinetics and structural integrity as a result of amorphous structure, oxygen deficiency, and nanoporous architecture.