Template-free water splitting preparation of carbon nanotube foam for high-efficiency charge storage and electromagnetic interference shielding

Abstract

With the wide applications of wearable and portable devices, there is a rising requirement to construct multi-functional materials featuring both high-efficiency charge storage and electromagnetic interference (EMI) shielding effectiveness (SE). Here, a facile template-free water splitting process is put forward by treating carbon nanotube paper (CNTP) to obtain carbon nanotube foam (CNTF). The resulting CNTF serving as electrode yields the specific capacitance as high as 513.8 F g⁻¹ at 1 A g⁻¹ and outstanding EMI SE of 74.7 dB, while those of CNTP are 21.4 F g⁻¹ and 46.1 dB, respectively. When used as the current collector, CNTF demonstrates significant benefits for the efficient utilization of polyaniline (PANi) by the elimination of the distinct interface between the current collector and the active material. Additionally, PANi exhibits increased roughness and a higher degree of doping when combined with CNTF. The CNTF/PANi electrode, with a PANi loading of 3.63 mg cm⁻², achieves the areal-specific capacitance of 2035.6 mF cm⁻², over twofold higher than that for the CNTP/PANi electrode. A flexible electrochemical capacitor assembled by CNTF/PANi electrodes exhibits 85.6 % of capacitance retention ratio after bending for 1000 times, while a device based on CNTP/PANi electrodes only retains 31.3 %.