Biomass materials with representative morphologies and compositions were employed to study the activation effect of KHCO₃. As the activation time increased from 1 to 3 h, the products derived from puffed rice and pleurotus eryngii achieved a hierarchical porous structure, while the products derived from cotton still presented a microporous structure. In the electrochemical test of a three-electrode system, the specific capacitance of these products was 352, 319, and 216 F g⁻¹, respectively. In the two-electrode system, the PR-2-based symmetric supercapacitor presented with a specific capacitance of 280.7 F g⁻¹ at 0.5 A g⁻¹, and the energy density of 14.03 Wh kg⁻¹ at 150.04 W kg⁻¹ and an energy density retention of 73.7% was at an even higher power density of 8380.4 W kg⁻¹. After 10,000 cycles of charging and discharging at 5 A g⁻¹, the specific capacitance retention of the supercapacitor reached 108.8%. Based on the experimental analysis, a likely mechanism for the formation of pores was proposed. The results indicate that biomass materials with soft layered or a network structure are the best candidates to obtain a hierarchical porous structure by KHCO₃ activation.

Silicon is a promising anode material for high-performance lithium-ion batteries (LIBs), but its rapid capacity degradation has significantly hindered its large-scale application. In this study, we propose an in situ self-assembly polymerization method to fabricate a stable silicon-based anode by leveraging electrostatic self-assembly technology, in situ esterification, and amidation reactions. The incorporation of a cross-linked polymer, combined with the synergistic effects of electrostatic interactions between negatively charged MXene and positively charged silane-coupling-agent-modified silicon, offers a novel strategy for enhancing the electrochemical performance of LIBs. Notably, annealed electrodes with a 65 wt% nmSi-NH₂/MXene ratio demonstrate outstanding electrochemical performance, achieving a capacity of 929.5 mAh g⁻¹ at a current density of 1 A g⁻¹ after 100 charge/discharge cycles. These findings suggest that the integration of cross-linked polymers and electrostatic self-assembly can significantly improve the intercalation and overall electrochemical performance of silicon anodes in lithium-ion batteries.

Hierarchical porous activated carbon derived from pleurotus eryngii was prepared by a one-step activation method. It was found that the specific surface area of the obtained sample increased with the increase in activation temperature (700–900 °C). The sample activated at 900 °C has a specific surface area of 2002.2 m² g⁻¹ and the highest specific capacitance (319 F g⁻¹), which is mainly attributed to the high utilization rate of specific surface area brought by the hierarchical porous structure. The assembled PEK-900//PEK-900 capacitor measured a specific capacity of 258 F g⁻¹ at a current density of 0.5 A g⁻¹. After 10,000 cycles of charging and discharging, the specific capacitance increased by 10%. Based on the correlation analysis of experimental data between the specific capacitance and pore structural parameters, Lasso dimensionality reduction and binary linear regression were used to reveal the relationship between the two. The residual sum of squares obtained by this method decreased by 38.4% compared to the univariate linear regression, providing a simple and reliable theoretical method for predicting the capacitance performance of biomass carbon materials.