Boosting Areal Capacitance and Energy Density of a Flexible Supercapacitor Based on High-Mass-Loading Layered Double Hydroxides

Flexible electrodes with a high density of active material loading as well as abundant charge transfer channels are crucial for high-performance wearable energy storage devices, and their fabrication also remains a great challenge. In this work, we report a hierarchical binder-free flexible electrode based on carbon nanosheets and a high-mass-loading CoNi-layered double hydroxide (11.8 mg cm–2) core–shell structure on the carbon clothe support (denoted as CC/CNs@CoNi-LDH). The as-synthesized CC/CNs@CoNi-LDH electrode delivers a superior mass energy density of 69.8 W h kg–1, a power density of 4.3 kW kg–1, and excellent stability with a retention of 91.1% of the initial capacitance even after 10,000 cycles. Moreover, ex situ techniques including X-ray photoelectron spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy were carried out to identify the structure evolution and the electrochemical reaction mechanism of CC/CNs@CoNi-LDH. This work suggests a facile route to construct a binder-free electrode with a high-mass-loading, which is promising for the development of energy storage systems.