Enhancing electrochemical performance of lignin-based carbon fibrous aerogels via boron doping

Self-supported hardwood kraft lignin (HKL)/graphene-based carbon fibrous aerogel (L/GCA) presents a fascinating prospect as the electrode of supercapacitor due to its impress rate capacity and cyclic stability. However, the hydrophobicity nature of L/GCA hampers the ion transfer between the electrode and electrolyte, thereby limiting its electrochemical performance. To address this, we enhanced the electrochemical performance of L/GCA through boron doping based on the improvement of hydrophilicity and the re-arrangement of electron density. The interaction between boron and L/GCA, as well as the effects of boron on the morphology, crystalline structure, wettability, and electrochemical performance were systematically investigated. Results indicate that boron doping increased the layer spacing of graphite lamella, reduced the degree of graphitization, and enhanced the hydrophilicity of L/GCA. These characteristics resulted in improved specific capacitance, rate capacity, and cyclic performance of boron doped L/GCA (B-L/GCA). The measured specific capacitance of the B-L/GCA-1.5-based electrode was 228 F g^-1 at a current density of 0.5 A g^-1, with a residual ratio of 113 % after 1000 cycles. The doping strategy presented in this study provides inspiration for enhancing the electrochemical properties of lignin-based carbon materials.