Chi Xu,Zhening Zhou,Wanwan Li,Xuanzhen Fan,Shihao Meng,Zonghao Lai,Wei Tang,Wenli Zhang,Sheng Li,Lijian Leng,Hao Zhan,Hailong Li
Bamboo-derived hard carbon emerges as a sustainable anode candidate for sodium-ion batteries, yet its electrochemical performance is hindered by inherent impurities and disordered microstructures. This study explores the synergistic effects of acid-leaching and pre‑carbonization, prior to high-temperature carbonization at 1300 °C, on enhancing sodium storage performance. Acid-leaching at 80 °C with a solid-liquid ratio of 1:15 for 30 min using 6 wt% HCl selectively removes hemicellulose and ash while reducing oxygen-containing groups, leading to an increase in edge defects and the retention of C O functional groups. These two active sites act as pseudocapacitive centers, enhancing capacity in the sloping region. Pre‑carbonization at 500 °C generates interconnected mesopores (0.038 cm 3 g −1 ), facilitating sodium-ion insertion in the plateau region. Additionally, the high carbon to oxygen ratio from acid-leaching, together with the enhanced graphite stacking (L c = 1.202 nm) induced by pre‑carbonization, improves the electrical conductivity and ion diffusion capability of the hard carbon. Compared with hard carbons derived from AcOH-leached, water-treated, and raw feedstocks, the HCl-leached hard carbon anode exhibits a higher initial Coulombic efficiency (70.4 %), enhanced rate capability (201.4 mAh g −1 at 5C), and a 32 % reduction in charge-transfer resistance. These findings highlight the role of structural engineering in enhancing renewable energy storage, directly linking microstructural modifications to electrochemical performance for sustainable design of high-performance biomass-derived sodium-ion battery anodes.
The capacitive properties of supercapacitors highly rely on the reasonable design of high-performance electrode materials. Herein, a synergetic strategy of pre-oxidation and pre-carbonization is proposed to prepare coal tar pitch (CTP) based porous carbon. The formation mechanism of porous carbon is revealed. Pre-oxidation increases the heteroatom content and promotes the decomposition of polycyclic aromatic hydrocarbons into small molecules, which is more conducive to improving the subsequent activation and enhancing the microporous specific surface area. Also, the autoclave pre-carbonization promotes the polymerization of the precursors and increases the carbon yield. Benefiting from the synergistic effect of pre-oxidation and pre-carbonation, the obtained carbon exhibits a superior specific capacitance of 365 F g −1 . Meanwhile, ZnCl 2 is used as a hydrogen-bonding acceptor to synthesize ZnCl 2 -EG/PVA deep eutectic solvent (DES) gel, and it is applicable to acidic, neutral, and alkaline electrolytes. The capacitor assembled with the prepared porous carbon and DES gel electrolyte achieves a high energy density of 41.3 Wh kg −1 and works well in unconventional temperatures (−40–75 °C). This work confirms the effect of pre-oxidation and pre-carbonization on the fabrication of CTP-based carbon material and expects to prepare porous carbon using other pre-oxidation/carbonization agents.
In this study, we report the rational design and synthesis of carbonized NiFe 2 O 4 superparticles (CarSPs) hierarchically integrated with densely aligned carbon nanotube (CNT) architectures, hereafter denoted as CarSP-CNTs, which exhibit a biomimetic urchin-like morphology. Through exploitation of the colloidal self-assembly and catalytic functionalities inherent to NiFe 2 O 4 nanoparticles (NPs), we achieve seamless integration of one-dimensional CNT arrays with three-dimensional superstructural frameworks. Systematic investigation reveals that the pre-carbonization of surface-bound organic ligands coupled with subsequent CNT growth induces synergistic interplay between conductive carbon matrices and active spinel oxide phases. This structural optimization confers CarSP-CNTs with enhanced charge transfer kinetics and catalytically robust interfaces, as evidenced by their superior electrocatalytic performance for the oxygen evolution reaction (OER) in alkaline electrolyte (1 M KOH). The optimized CarSP-CNTs exhibit a minimal overpotential of 307 mV to deliver a current density of 10 mA cm −2 , alongside remarkable operational stability exceeding 20 h of continuous electrolysis. These findings establish a paradigm for the rational design of hierarchically structured, multi-component electrocatalysts through coordinated nanoscale engineering, offering a versatile platform for advancing energy conversion technologies.
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