Cold‐Resistant Nitrogen/Sulfur Dual‐Doped Graphene Fiber Supercapacitors with Solar–Thermal Energy Conversion Effect

Abstract

Although graphene fiber‐based supercapacitors are promising for wearable electronic devices, the low energy density of electrodes and poor cold resistance of aqueous electrolytes limit their wide application in cold environments. Herein, porous nitrogen/sulfur dual‐doped graphene fibers (NS‐GFs) are synthesized by hydrothermal self‐assembly followed by thermal annealing, exhibiting an excellent capacitive performance of 401 F cm−3 at 400 mA cm−3 because of the synergistic effect of heteroatom dual‐doping. The assembled symmetric all‐solid‐state supercapacitor with polyvinyl alcohol/H2SO4/graphene oxide gel electrolyte exhibits a high capacitance of 221 F cm−3 and a high energy density of 7.7 mWh cm−3 at 80 mA cm−3. Interestingly, solar–thermal energy conversion of the electrolyte with 0.1 wt % graphene oxide extends the operating temperature range of the supercapacitor to 0 °C. Furthermore, the photocatalysis effect of the dual‐doped heteroatoms increases the capacitance of NS‐GFs. At an ambient temperature of 0 °C, the capacitance increases from 0 to 182 F cm−3 under 1 sun irradiation because of the excellent solar light absorption and efficient solar–thermal energy conversion of graphene oxide, preventing the aqueous electrolyte from freezing. The flexible supercapacitor exhibits a long cycle life, good bending resistance, reliable scalability, and ability to power visual electronics, showing great potential for outdoor electronics in cold environments.

Optimized electron/ion transport by constructing radially oriented channels in MXene hybrid fiber electrodes for high-performance supercapacitors at low temperatures

“…Graphite oxide was synthesized by oxidizing graphite akes (1000 mesh, Huadong Graphite Factory) by the modied Hummers' method. 11,48 The obtained graphite oxide powder was congured to a concentration of 10 mg mL −1 and sonicated for 30 min to obtained the aqueous GO dispersion.…”

“…[4][5][6][7][8][9][10] The electrode materials that can reversibly adsorb-desorb ions are of critical importance for ber supercapacitors. Two-dimensional (2D) functional nanomaterials such as graphenes 11 and MXenes 12 have been extensively investigated for ber electrodes because of their large surface area, high electronic conductivity, and strong interlayer forces.…”

Heteroatom Codoped Graphene: The Importance of Nitrogen

“…The quest for dye-sensitized solar cells with higher efficiency has also tested if the inclusion of S and N codoped graphene can be useful. − The advantages of codoping as compared with the monodoping when preparing dye-sensitized solar cells (DSSCs) were also confirmed by Luo et al A power conversion efficiency (PCE) of 4.23% was obtained for sulfur reduced graphene oxide, while for sulfur and nitrogen reduced graphene oxide the value increased to 4.73%. In 2015, Xu et al built bifacial DSSCs capable of utilizing incidental light from the rear and front sides that relied on transparent S and N codoped graphene as counter electrodes.…”

Energy Solutions for Wearable Sensors: A Review

“…Solar energy can also help optimize the performance of energy storage modules and thus can be more stable and adaptable for wearable electronics. Researchers used graphene oxide as solar-thermal conversion section to improve the low-temperature resilience of a supercapacitor [ 38 ]. In addition to high flexibility and scalability, this new design of a fiber-based supercapacitor can absorb and make use of sunlight energy to guarantee operation under extreme low temperatures ( ), and thus is a promising choice of a combined energy harvesting and storage device for wearable and portable biosensors.…”