Sustainable biomass-based hierarchical porous carbon for energy storage: A novel route to maintain electrochemically attractive natural structure of precursor

Deep learning prediction and experimental investigation of specific capacitance of nitrogen-doped porous biochar

N-doped porous biochar is a promising carbon material for supercapacitor electrodes due to its developed pore structure and high chemical activity which greatly affect the capacitive performance. Predicting the capacitance and exploring the most influential factors are of great significance because it can not only avoid the trial-and-error experiments but also provide guidance for the synthesis of biochar with the aim of capacitance enhancement. In this study, a CNN model with ReLU activation function was established using DenseNet architecture for specific capacitance prediction. The importance and impacts of the physiochemical properties of N-doped porous biochar to the capacitance were revealed. With the guidance of the model, N-doped porous biochar samples with high capacitance were synthesized, the data of which were further used for model validation. This study provides not only a deep learning model which can be used in practice for capacitance prediction but also directions for the synthesis of N-doped porous biochar with high capacitive performance.

Sustainable Lignin-Derived Hierarchical Porous Carbon for Supercapacitors: A Novel Approach for Holding Electrochemical Attraction Natural Texture Property of Precursor

Finding low-cost and environmentally friendly precursors that can maintain their electrochemical attraction natural texture properties while obtaining hierarchical porous carbons with high electrochemical performance is desirable for offering a leap forward in industrial applications. However, phenomena associated with the high microporosity of porous carbon remain. Herein, the protective effect of hydrothermal methods and the micropore-forming ability of KOH were used. The as-synthesized porous carbon (PC-1) holds the natural texture property (the retention of texture property with apertures higher than 2 nm was up to 80%) and achieves three-dimensional (3D) architecture with hierarchical structures accompanied by an ultrahigh specific surface area (3559.45 m²/g). Benefiting from its texture properties, PC-1 possesses a high specific capacitance of 288.75 F/g at 0.5 A/g, excellent rate capability as high as 223.72 F/g at 10 A/g, and remarkable conductivity in a three-electrode system with a 6 M KOH electrolyte. In view of its environment friendliness, low cost, and excellent specific capacitance, PC-1 has promising applications in high-performance supercapacitors.

Upcycling of PET waste into methane-rich gas and hierarchical porous carbon for high-performance supercapacitor by autogenic pressure pyrolysis and activation

The explosive growth of polyethylene terephthalate (PET) wastes has brought serious pollution to the environment. Here, PET waste was upcycled into methane-rich pyrolysis gas and carbon material for energy storage through autogenic pressure pyrolysis and post-activation. The pyrolysis gas contained 34.58 ± 0.23 vol% CH₄. After CO₂ removal, the high caloric value of the pyrolysis gas could reach 29.2 MJ m^-3, which could be used as a substitute natural gas. Pyrolytic carbon was further activated by KOH and ZnCl₂. KOH-activated carbon (AC-K) obtained a hierarchical porous structure, a high specific surface area of 2683 m² g^-1 and abundant surface functional groups. Working as supercapacitor electrodes, AC-K exhibited an outstanding specific capacitance of 325 F g^-1 at a current density of 0.5 A g^-1. After 5000 charge-discharge cycles, AC-K still retained 91.86% of the initial specific capacitance. This study provides a sustainable way to control plastic-derived pollution and alleviate the energy crisis.