Preparation Of Gum Arabic-based Carbon Materials And Their Application In Rechargeable Batteries

With the rapid development of new energy electric vehicles and other fields,there is an urgent need to develop high-performance energy storage materials to meet people's increasing demands and requirements for energy storage and functional systems in these fields.The most concerned and most promising energy storage and functional system of chemical power source.Lithium ion secondary batteries that have been commercialized and new energy rechargeable batteries such as sodium ion batteries and lithium sulfur batteries that have application prospects are particularly favored by researchers and users.However,the electrode materials that determine the performance of these rechargeable batteries still face many problems such as low reversible specific capacity,and there is an urgent need to develop electrode materials with low cost and high energy density.The carbon material has a lower lithium intercalation potential,which can slowly reduce and avoid the deposition of lithium dendrites.It also has good electrical conductivity,which facilitates the rapid migration of electrons and ions,and improves the electrochemical performance of the battery.Biomass,as a carbon material raw material,has many advantages such as environmental protection,wide sources,etc.,and has great application prospects and economic value.In this paper,the cheap biomass-gum arabic is selected as the carbon source,to study the preparation process and the influence law of parameters on the morphology,structure,carbon materials and optimizing,inspect the materials in lithium ion batteries,sodium ion battery and lithium sulfur batteries in the electrochemical properties,and structure-activity relationship studies,in order to obtain good electrochemical performance of carbon-based material.The main findings are as follows:1.Optimization of preparation technology and electrochemical performance of gum arabic-based carbon materials.Using gum arabic as the carbon source and zinc chloride as the activator,adopting high temperature pyrolysis carbonization method,and investigate and optimize the influence of the preparation process parameters such as calcination temperature and raw material ratio on the morphology and structure of carbon materials.A series of carbon-sulfur composite materials and carbon anode materials were prepared,and their electrochemical properties and structure-activity relationships were studied.The experimental results show that the porous carbon material obtained when the mass ratio of zinc chloride to gum arabic is 3:1 and the pyrolysis carbonization temperature is 800?has the best electrochemical performance.When used as anode material for lithium ion battery,its delivers the first reversible specific capacity of 610.5 mAh g^-1 at current density of 200 mA g^-1,the reversible specific capacity of 357.3 mAh g^-11 after 200 cycles and a capacity retention of 58.5%.As a anode material for sodium ion battery,its delivers the first reversible specific capacity of 93.0 mAh g^-1 at a current density of 200 mA g^-1,the reversible specific capacity of 100.5 mAh g^-1 after 100 cycles and a capacity retention of 108.1%.After treatment with elemental sulfur at 155°C×12 h+180°C×12 h,a carbon-sulfur composite material containing 70 wt.%sulfur was obtained,and as a cathode material for lithium-sulfur battery,the first reversible specific capacity of 997.7 mAh g^-1 at a current density of 200 mA g^-1,the reversible specific capacity of 268.9 mAh g^-1 after200 cycles,and the reversible specific capacity of 192.1 mAh g^-1 at a current density of 1000 mA g^-1 after 700 cycles.In conclusion,the excellent electrochemical performance is attributed to the developed porous structure and high specific surface area of carbon-based materials,which facilitate the rapid transport of lithium ions.2.Study on modification of acacia-based carbon materials.Using gum arabic as carbon source,thiourea?CN₂H₄S?as nitrogen and sulfur source,iron nitrate?Fe?NO₃?₃·9H₂O?as graphitization promoter,and silicon dioxide?SiO₂?as structural template,and nitrogen/sulfur co-doped porous carbon composites were prepared by the pyrolysis carbonization method,The influence of preparation process parameters such as calcination temperature,nitrogen and sulfur content,graphitizing agent and raw material ratio on its morphology,structure and electrochemical performance when used as a anode material for lithium/sodium ion batteries were investigated.The experimental results show that the nitrogen/sulfur co-doped porous carbon composite material obtained after calcining at 800?is mixed with gum arabic,thiourea,iron nitrate,and silica at a mass ratio of 1:4:1:4.Has the best electrochemical performance.When used as anode material for lithium ion battery,its delivers the first reversible specific capacity of 938.7 mAh g^-1 at a current density of 200 mA g^-1,the reversible specific capacity of 1172.6 mAh g^-1 after 200 cycles and a capacity retention of124.9%;the reversible specific capacity of 769.2 mAh g^-11 at a current density of 500mA g^-1 after 350 cycles;and the rate test shows that the first reversible specific capacity of 1096.8 mAh g^-1 at a current density of 100 mA g^-1,when the current density was reduced back to 100 mA g^-1,its specific capacity was about 1048.0 mAh g^-1.When used as a anode material for sodium ion batteries,the first reversible specific capacity of 342.5 mAh g^-1 and the reversible specific capacity of 269.4 mAh g^-1 at a current density of 100 mA g^-1 after 200 cycles.After treating it with elemental sulfur at 155°C×12 h+180°C×12 h and the nitrogen/sulfur co-doped porous carbon-sulfur composite containing 70 wt.%sulfur was obtained,when as a cathode material for lithium-sulfur battery,its delivers the first charging/discharging specific capacity of 965.9/975.7 mAh g^-1,and the charging/discharging capacity of178.4/177.9 mAh g^-1 at a current density of 200 mA g^-1 after 200 cycles and its capacity retention of 18.5%.The good electrochemical performance is attributed to the dope of nitrogen and sulfur increasing the active sites of the material,there by increasing the lithium/sodium storage sites.3.Optimization of preparation process and electrochemical performance of acacia-based carbon materials coated with cobalt sulfide.Using gum arabic as the carbon source,cobalt chloride as the cobalt source,and thioacetamide as the sulfur source,by one-step hydrothermal and high-temperature pyrolysis methods prepared carbon-coated cobalt sulfide?CoS_x@C?composites.The influence of preparation process parameters such as time,carbon coating amount,and calcination temperature on its morphology,structure,and electrochemical performance when used as a anode material for lithium/sodium ion battery.The experimental results show that when gum arabic,cobalt chloride,and thioacetamide are mixed at a mass ratio of 3:1:3,after hydrothermally treated at 200?×12 h and carbonized at 800?high temperature,the carbon-coate cobalt sulfide composite material obtained,and has optimal electrochemical performance.When used as a anode material for lithium ion battery,its delivers the first reversible specific capacity of 1110.5 mAh g^-1 and the reversible specific capacity of 909.7 mAh g^-1 at a current density of 100 mA g^-1 after 60 cycles and its capacity retention of 81.9%;At a high current density of 500 mA g^-1,the first reversible specific capacity of 710.2 mAh g^-1 and the reversible specific capacity of789.8 mAh g^-1 after 330 cycles.When used as a anode material for sodium ion batteries,the first charging/discharging specific capacity of 531.9/885.3 mAh g^-1 at a current density of 100 mA g^-1 and the first coulomb efficiency of 60.1%,and the reversible specific capacity of 12.3 mAh g^-1 after 60 cycles and a capacity retention of23.1%.After treatment with elemental sulfur at 155°C×12 h+180°C×12 h,a carbon-coated cobalt sulfide/sulfur composite material containing 70 wt.%sulfur was obtained.As a cathode material for lithium-sulfur battery,the first charging/discharging specific capacity of 223.9/289.4 mAh g^-1 and the reversible specific capacity of 59.9 mAh g^-1 at a current density of 500 mA g^-1 after 100 cycles.The good electrochemical performance is attributed to the in-situ coated carbon which is beneficial to limit the volume expansion of CoS_x and increase the conductivity of the composite.