Fabrication Of Porous Carbon Electrode Material With High Specific Capacity And Its Performance In Supercapacitors

Carbon material is a reliable choice for electrode materials of energy storage devices such as supercapacitors and lithium-ion batteries due to its abundant pores,excellent conductivity,diverse forms,and stable three-dimensional structure.Meanwhile,carbon material prepared by laser induction technology also demonstrate the advantages of high crystal quality and macro thickness,which gradually become the focus of current research.Herein,phenolic resin（PR）was selected as the precursor of carbon materials prepared by laser induction method.Firstly,a CO₂ laser of 10.6 micron wavelength was selected,and an oxygen-rich porous carbon material（LPC）was prepared by adjusting its power,sweep speed and line spacing.On this basis,the influence degree of activation treatment on the performance of carbon electrode supercapacitors is explored and the mechanism of capacitor enhancement is analyzed.Then,based on the preparation of LPC,the amorphous carbon material LPC was transformed into porous graphene LPG by multi-step laser method.Finally,the effect of low boiling point pore-making agent on the pore growth of PR precursor was investigated under the condition of LPG preparation,and the electrochemical properties of the two were compared.The main research conclusions are as follows:（1）The morphology and properties of LPC are obviously affected by laser parameters.At the laser scanning rate of 15 mm s^-1 and laser spacing of 0.1 mm,LPC prepared with 4.5 W shows the greatest advantages,demonstrating the 3D porous structure,high active layer thickness（221μm）,and excellent electrical conductivity(6.56Ωsq^-1).（2）The precursor solution prepared by the solvent removal method possesses high oxygen content,and part of it remains in the LPC after laser irradiation.The selection of immersion and ultrasonic physical activation as well as electrochemical activation at 20,50 and 100 mV s^-1 voltage sweep rate can promote the free oxygen atoms inside LPC to undergo different degrees of oxygen functional group conversion reactions,providing reversible redox reactions in electrochemical tests,and effectively improving the electrical storage capacity of the material.（3）LPC prepared at different laser power exhibited the best electrochemical performance after pre-activation at 20 mV s^-1.The LPC sample at 4.5 W has a specific capacity of 778.3 m F cm^-2 at the current density of 0.2 m A cm^-2.After assembling the all-solid-state supercapacitor(ASS（C）,it still displays excellent energy storage capacity and ultra-high cycle stability,which proves the possibility of applying LPC to high performance energy storage devices.（4）LPG prepared by scanning three times with decreasing laser power not only retains the advantages of LPC performance,but also solves the problem of poor structural stability of amorphous LPC.The high stability of sp2 hybrid carbon atoms in LPG provides a possibility for the preparation of high-performance flexible wearable devices.（5）After adding a certain proportion of Urea（Urea）to the PR precursor to modify the carbon precursor,the prepared LPG-Urea sample exhibited better pore distribution,which enabled it to have excellent performance in both the electrode material and ASSC-Urea devices.