Studies On The Synthesis Of Biomass-based Activated Carbon Materials And Their Electrochemical Properties

Supercapacitors and lithium-ion batteries are effective new energy storage devices for new energy storage and conversion technology.Electrode materials are an important part of electrochemical energy storage devices and the preparation of electrode materials with low production cost,long service life,high capacity and environmental friendliness has been the focus of research.Biomass is considered as a high-quality carbon source for the preparation of activated carbon materials because of its rich resources,low cost,environmental protection and renewable advantages The application of biomass carbon materials to electrochemical energy storage is not only in line with the green environmental protection but also promotes sustainable development,and has good practical application prospects.In this paper,we designed and prepared a series of carbon-based materials with excellent electrochemical performance in supercapacitors and lithium-ion batteries using plant waste as the raw material of biomass carbon materials,and actively studied the relationship between material properties and electrochemical performance.The main research contents were as follows:(1)The active carbon materials with different KOH activation,N/S co-doping and pre-carbonization were studied and prepared by using the Jutmelo stem as carbon source,KOH as activator and thiourea as dopant,and used as electrode material in supercapacitors.The active biomass carbon had a high specific surface area of 1783.711 m2 g-1 when the mass ratio of KOH to biomass was 1:2,and the specific capacitance reached 193 F g-1 at the current density of 1 A g-1.The preparation of N/S co-doped biomass activated carbon can be realized by using thiourea as dopant.The CF-K2-T2 sample had 211.5 F g-1 specific capacitance at the current density of 1 A g-1.The activated carbon material prepared by pre-carbonization of biomass,KOH activation and N/S co-doping have three-dimensional porous structure,which can obtain 299.1 F g-1 high specific capacitance at the current density of 0.5 A g-1.(2)The tri-layer carbon material with π-π stacking interaction(CC/ECC@BMDC)was prepared by using brown bean husk as the biomass carbon source,combined with electro-activated modified carbon cloth,and used as a self-supporting electrode directly used as the negative electrode of lithium-ion batteries.The results showed that the CC/ECC@BMDC electrode in lithium-ion half-cell battery had a high area specific capacity of 2.53 mAh cm-2 at the current density of 0.2 mA cm-2.And the long cycle performance test with the current density of 2.0 mA cm-2 for 200 cycles can keep more than 90%of the initial capacity.In addition,the CC/ECC@BMDC electrode and LiNi0.8Co0.1Mn0.1O2(NCM)cathode were assembled into a full-cell battery.The area capacity of 0.48 mAh cm-2 was obtained at the current density of 0.2 mA cm-2,and the cyclic performance test showed excellent cycle stability at the current density of 0.4 mA cm-2.Through characterization analysis such as XPS and FTIR,it was showed that there was π-π stacking interaction in CC/ECC@BMDC.Furthermore,ex-situ characterization and DFT calculation were used to study CC/ECC@BMDC of π-π stacking interaction and lithium-ion intercalation storage mechanism.(3)High performance carbon materials(CC@BMDC and CC/ECC@BMDC)were prepared by using brown bean husk as carbon source,combining with carbon cloth and electrochemically activated carbon cloth respectively.And they were applied to supercapacitor for electrochemical performance research.The results showed that the CC/ECC@BMDC electrode has excellent electrochemical performance in two different electrolyte,6 M KOH and 5 M LiCl.The high area specific capacitance of 1336 mF cm-2 was obtained at the current density of 2 mA cm-2 in 6M KOH electrolyte,and 1014.8 mF cm-2 area specific capacitance was obtained at the current density of 4 mA cm-2 in 5 M LiCl electrolyte.In addition,TiN@MnO2 and NiMoO4/MoO2/P cathode materials were used to match CC/ECC@BMDC to form asymmetric two electrode supercapacitor,which can show higher energy density and power density.