Preparation And Electrochemical Performance Of Aspergillus Niger-based Carbon Materials

The rapid development of new energy technology has put forward higher requirements on the environmental protection and performance of electrode materials,and in order to reach the goal of"carbon peaking"and"carbon neutral",it has become a trend to seek low-cost,non-polluting carbon materials.Among many materials,biomass materials are undoubtedly the most abundant,inexhaustible and inexhaustible resources on earth,and have attracted great attention from scientists.China’s fermentation industry is well developed,while producing countless bacteriological waste residue,only in the fermentation of Aspergillus niger to produce sodium gluconate process,each produced 1 ton of product will produce 0.1 tons to 0.3 tons of Aspergillus niger bacteriological waste residue.The waste residue,if piled up for a long time,not only pollutes the atmosphere,soil and groundwater environment,but also causes a waste of resources and reduces the economic benefits of the enterprise.Therefore,this project selects Aspergillus niger slag as the research object,and investigates the electrochemical properties of this special material after carbonization and activation treatment,and studies its application prospects in the field of lithium-ion battery cathode materials,the specific investigations are as follows:（1）The direct carbonization method was used to treat Aspergillus niger residue,and the results showed that the direct carbonization method can successfully prepare in situ nitrogen-doped biomass hard carbon materials,among which the material JC-600 obtained by direct carbonization at 600℃has relatively good electrochemical properties,and its specific capacity as a lithium-ion battery anode can be stabilized at 230 m Ah/g after 200 cycles at100 m A/g current density.But its first charge/discharge efficiency is only51.8%,and it has a high electrochemical impedance due to the influence of impurities in the material,and its multiplicative performance at a high current density of 2 A/g is only 75 m Ah/g remaining.（2）Pretreatment of Aspergillus niger residue with three reagents,HCl,KOH and C₂H₅OH,and investigation of the effect of pretreatment methods on the morphological structure as well as electrochemical properties of the material.For Aspergillus niger,some of the macromolecules in the cells will be lost with alkali or alcohol washing,which affects the microstructure of the material after high temperature carbonization and makes the electrochemical performance of the material significantly reduced;while acid washing can remove the impurities affecting the performance of the material,which makes the material electrochemical impedance reduced,thus making its electrochemical performance enhanced.The specific capacity of the carbonized material JC-HCl-600,which was used as the anode of lithium-ion battery after 100 cycles at 100 m A/g current density,was also stabilized at about 304 m Ah/g,and its first Coulomb efficiency was increased from 51.8%to about 56.4%,and the multiplicity performance was also improved（168 m Ah/g remaining at 2 A/g）.（3）Chemical activation was used to prepare the derived carbon materials using KOH,Zn Cl₂and Zn（NO₃）₂as activators,respectively.The material JC+Zn（NO₃）₂-600 prepared using Zn（NO₃）₂as an activator has a large specific surface area of 501 m²/g and an abundant microporous mesoporous structure,and exhibits a stable at 100 m Ah/g at The high specific capacity of 420 m Ah/g and the excellent multiplicative performance.The improvement in cycling and multiplication performance is mainly due to the improvement of the internal structure of the carbon material.The formation of a layered pore structure inside the Aspergillus niger-derived carbon material under the action of the activator Zn（NO₃）₂improves the lithium-ion transport rate and also increases the abundance of active sites,which facilitates the adsorption of lithium-ions.