In Situ Doping Boron Atoms into Porous Carbon Nanoparticles with Increased Oxygen Graft Enhances both Affinity and Durability toward Electrolyte for Greatly Improved Supercapacitive Performance

Supercapacitors represent an important energy storage system for high power applications with carbon electrodes acting as the key component. Design and synthesis of advanced carbon materials with supercapacitive activity (capacitance and rate capability) and stability have been the focus of supercapacitor developments. This study reports a high‐performance carbon electrode by in situ doping boron atoms into nanoporous carbon particles, which is achieved by a continuous spraying assisted coassembly process. Boron doping leads to extra oxygen graft into carbon surface, enabling both enhanced wettability and durability for the fabricated carbon electrodes. Density functional theory calculations further suggest that boron doping enhances electrolyte ion penetration and interactions with carbon surface, leading to the improved capacitances and rate capability. The constructed symmetric aqueous supercapacitor exhibits all‐round performance improvements including high energy density (9.1 Wh kg −1 ) and power density (24.1 kW kg −1 ) as well as ultralong cycling life (100 000 cycles). This work for the first time provides insights into the role of boron doping in enhancing both supercapacitive activity and stability of carbon materials for high‐performance supercapacitors.