Fabrication of multi-purposed supercapacitors based on N-doped porous carbon framework

Abstract

The development of versatile supercapacitors is becoming a new trend to meet the needs of different application scenarios, including high/low temperature and flexible features and so on. In this paper, wide-temperature range and flexible supercapacitors are constructed using hierarchical porous N-doped carbon framework (N-CF) and gel electrolyte, where N-CF is prepared via one-step pyrolysis of potassium citrate and anion exchange resin (AER) sol. Findings indicate that the porous structure and the specific surface area electrode materials play different roles in electrochemical performance of electrical double-layer capacitors (EDLCs). The coexistence of micropore and mesopore endows carbon materials with excellent performance including high specific capacitance (316 F g−1 at 1 A g−1) and rate capability (retention of 77 % from 1 to 100 A g−1). Moreover, pseudocapacitance coming from O-/N-containing function groups is estimated on the basis of cyclic voltammogram curves to explain the capacitance contribution. Additionally, polyvinyl alcohol (PVA)-based gel electrolyte is fabricated through low-temperature self-crosslinking by incorporating ethylene glycol/water (EG/H2O) binary solvent, which gives EDLCs a high energy density of 20.1 Wh kg−1 at power density of 0.45 kW kg−1 under 20 °C. Remarkably, the introduce of gel electrolyte can also make EDLCs low-temperature tolerant (a high energy density of 17.4 Wh kg−1 and excellent cycle stability under −20 °C), and wearable, which can meet the needs of different application scenes.