Heteroatom tuning in agarose derived carbon aerogel for enhanced potassium ion multiple energy storage

Abstract

Abstract The incorporation of heteroatoms into carbon aerogels (CAs) can lead to structural distortions and changes in active sites due to their smaller size and electronegativity compared to pure carbon. However, the evolution of the electronic structure from single‐atom doping to heteroatom codoping in CAs has not yet been thoroughly investigated, and the impact of codoping on potassium ion (K+) storage and diffusion pathways as electrode material remains unclear. In this study, experimental and theoretical simulations were conducted to demonstrate that heteroatom codoping, composed of multiple heteroatoms (O/N/B) with different properties, has the potential to improve the electrical properties and stability of CAs compared to single‐atom doping. Electronic states near the Fermi level have revealed that doping with O/N/B generates a greater number of active centers on adjacent carbon atoms than doping with O and O/N atoms. As a result of synergy with enhanced wetting ability (contact angle of 9.26°) derived from amino groups and hierarchical porous structure, ON‐CA has the most optimized adsorption capacity (−1.62 eV) and diffusion barrier (0.12 eV) of K+. The optimal pathway of K+ in ON‐CA is along the carbon ring with N or O doping. As K+ storage material for supercapacitors and ion batteries, it shows an outstanding specific capacity and capacitance, electrochemical stability, and rate performance. Especially, the assembled symmetrical K+ supercapacitor demonstrates an energy density of 51.8 Wh kg−1, an ultrahigh power density of 443 W kg−1, and outstanding cycling stability (maintaining 83.3% after 10,000 cycles in 1 M KPF6 organic electrolyte). This research provides valuable insights into the design of high‐performance potassium ion storage materials.

Keywords

• agarose
• carbon aerogels
• O/N/B codoping
• potassium‐ion battery
• potassium‐ion supercapacitor