Flash Joule Heating Enabled Instantaneous Purification and Strengthening of CNT Films for High-Performance Flexible Aluminum-Ion Batteries

Abstract

Flexible aluminum-ion batteries have demonstrated considerable potential in the field of wearable electronics due to their high safety, low cost, and excellent mechanical flexibility. However, a critical bottleneck hindering their advancement lies in the rapid and cost-effective fabrication of flexible cathode materials that simultaneously possess high conductivity, structural stability, and superior electrochemical activity. This work presents an experimental approach utilizing flash Joule heating technology to subject carbon nanotube films prepared by chemical vapor deposition to instantaneous high-temperature treatment. This study concurrently achieves the efficient purification of the CNT films (through the removal of Fe catalyst impurities) and structural reinforcement (via defect repair and significant enhancement of graphitization degree). The flash-heated CNT cathode exhibits outstanding comprehensive electrochemical performance: the CNT film treated at 1700 ℃delivers a specific capacity as high as 281.97 mAh g⁻¹ at a current density of 4 A g⁻¹, which is 7.57 times that of the pristine CNT film. CNT films treated at other temperatures (1400 ℃, 1200 ℃, and 1000 ℃) yield capacities of 177.91 mAh g⁻¹, 108.32 mAh g⁻¹, and 65.28 mAh g⁻¹, representing enhancements of 4.56, 2.78, and 1.68 times over the pristine film, respectively. This study demonstrates that flash Joule heating technology offers a rapid, efficient, and highly promising new pathway for the preparation of high-performance flexible energy storage electrodes.