分子模板诱导碱木质素基多孔比容炭的制备及其超级电容器储能性能

Preparation of Alkali Lignin-Based Porous Specific-Capacity Carbon Induced by Molecular Template and Its Energy Storage Performance for Supercapacitors

作为造纸产业的工业废料,碱木质素的高效利用十分有限。以碱木质素为主要原料、以蔗糖分子作为软模板,经预炭化与高温炭化两步,实现了木质素基多孔比容炭的简单、绿色及高效制备。表征与测试结果表明,其比表面积高达390 m^(2)/g,平均孔径为2.7 nm,主要以孔径小于1 nm的微孔形式集中分布。电化学测试结果显示,其在0.5 A/g的电流密度下,比电容可达243.5 F/g。这一提升归因于蔗糖软模板带来的丰富微孔结构。在10 A/g的大电流密度下,其比电容为199.9 F/g,比电容保持率约为82%,证明其具有良好的倍率性能。进一步将其组装为扣式超级电容器,展现出30.7 W·h·kg^(-1)的高能量密度(功率密度450 W/kg),在4500 W/kg的高功率密度下,电容器仍具有23.6 W·h·kg^(-1)的能量密度。在1 A/g的电流密度下,经过3000次循环测试,电容器的比电容保持率仍高达约98%,表现出出色的循环稳定性。本研究为碱木质素在电化学储能领域的应用提供了新方法。

The efficient utilization of alkali lignin,an industrial waste from the papermaking industry,is fairly limited.With the alkali lignin as primary raw material and sucrose molecule as soft template,simple,green and efficient preparation of porous specific-capacity carbon from lignin was achieved through a two-step process involving pre-carbonization and high-temperature carbonization.Characterization and test results reveal that the materials exhibit a specific surface area up to 390 m^(2)/g and an average pore size of 2.7 nm,and is predominantly concentrated in the form of micropores with a pore size smaller than 1 nm.Electrochemical test results show that a specific capacitance of 243.5 F/g is obtained at a current density of 0.5 A/g,probably ascribing to the rich microporous structure introduced by the sucrose soft template.The specific capacitance is 199.9 F/g at a high current density of 10 A/g,and the specific capacitance retention is about 82%,proving an excellent rate performance.The electrode was further assembled into a button-type supercapacitor,which reveals a high energy density of 30.7 W·h·kg^(-1)at a power density of 450 W/kg.And the capacitor still maintains an energy density of 23.6 W·h·kg^(-1)at a high power density of 4500 W/kg.After 3000 cycles of testing,the capacitor retains a specific capacitance retention up to about 98%at a current density of 1 A/g,demonstrating exceptional cyclic stability.The research provides a new approach for the application of alkali lignin in the field of electrochemical energy storage.