Study On Energy Storage Materials And Mechanism Of Single Cell Biological Absorption And Composite With Metal-Salt

Traditional fossil energy,such as oil,coal,natural gas,etc.,is not renewable,and they are in a depleted state.At the same time,the development and utilization of the traditional energy also bring environmental pollution.Therefore,scientists need to find or develop new sources of energy,such as wind and solar energy.At the same time,the efficient use and storage of energy are becoming increasingly urgent,and Li-ion batteries are characterized by high energy density,high capacity,lightweight,and memoryless;Supercapacitors stand out because of their high power density,long cycle life and high efficiency energy conversion.Equipment,mechanical and electronic products powered by lithium-ion batteries or supercapacitors such as:new energy vehicles,electrical bicycles and other electric products,notebook computers,mobile phones and other electronic products,electric bracelets,rechargeable clothing and other wearable daily necessities need these energy storage materials too.Based on the bright prospect of high performance energy storage materials and the problems existing in their applications,the author focuses on lithium-ion batteries and supercapacitors by using modern nanotechnology and biology technology.1.In chapter 2,the stability and performance of lithium-ion battery in application need to be further improved,in this chapter,combining the rise of the new wearable electronic device,a flexible Mn₂P₂O₇-C@RGO paper battery is prepared by using the bacteria to in-situ absorb metal cation Mn by the way of perfect coating the cationic metal Mn.By testing its performance,it turns out that the electrode prepared by this material is very stable and can be circulated for a long time without attenuation of specific capacity.At the same time,the performance of the battery is very good,the specific capacity of the battery is very high even when the current density increases continuously,when it finally returns to a small current density,it can still return to its original specific capacity at low current density.It has an average specific capacity of880.0 mA h g^-1 at a current density of 100 mA g^-1;when the current density is 1000 mA g^-1,the cycle is more than 200 cycles,the specific capacity is 585 mA h g^-1;when the current density is 5000 mA g^-1,and the current density is more than 2000 cycle,the specific capacity is 400 mA h g^-1.There is no metal salt impurity on the outer surface of bacteria or on the RGO surface,and the hollow carbon shell,after bacteria absorption and annealing,contains particles of metal salt.But if it the pure bacteria that do not absorb metal salts,the carbonation results show that there are no metal salt particles in it.This proves that bacteria have successfully absorbed metal cationic Mn into it,and achieved the goal of carbon coated metal salt at the same time.2.Because many kinds of bacteria enrich metal manganese cations,the lithium-ion batteries prepared present good performances.However,is it only suitable for the absorption of metal manganese cations by bacteria absorbing metal cations and recombining reduced graphene oxide,this paper also tries to test metal cations with poor enrichment.In chapter 3 of this paper,the author selects the metal nickel cation as the metal cation presoma absorbed by bacteria,prepared Ni₁₂P₅-C@RGO paper flexible battery.The prepared materials were then tested as electrodes for lithium-ion batteries.Through the comparison of pure bacteria,it is found that bacteria can also absorb Ni metal cations with poor metal enrichment,the cycle performance and rate performance of the battery are also better than that of graphite powder or carbon materials prepared by pure bacteria.It is particularly noteworthy that the cycle performance is very good,which can reach 5,000 cycles without attenuation.3.Bacteria can absorb metal cations,capsule metal salt cations perfectly proves to be feasible for lithium ion batteries.Then,not with bacteria,but with another primitive biology-salt algae whose tolerance of salinity is very high,whether it also produces a good performance for the li-ion batteries,in this paper,the fourth chapter has studied this condition,the metal tin cation is selected,at the same time,the ordinary lithium ion battery instead of the flexible lithium ion battery was prepared,and the results show that the performance is excellent.Its cyclic capacity can reach 619.09 mA h g^-1 at200 mA g^-1 current density,its capacity continues rising at a high current density of1000 mA g^-1,which can reach 574.97 mA h g^-1 at the highest point,demonstrating its excellent performance fully.4.In chapter 5 of this thesis,the author studies another kind of energy storage material supercapacitor,Zinc tungstate particles with binary metal oxide nanostructures were prepared by electrostatic spinning.Because the stability of zinc tungstate structure is very high,and zinc tungstate can precipitate easily,the author has not found the report that zinc tungstate nanomaterials have been prepared by electrospinning.Then the authors have prepared zinc tungstate nanoparticles by the method of electrostatic spinning.When the voltage measurement of zinc tungstate nanocrystalline electrode in this paper is from 0.3-0.55 at different current rates from2-100 A g^-1,the electrode exhibits high specific capacitance of 2590,2385,2355,2070,1880,1710,1600 and 1500 F g^-1 at high current densities of 2,5,10,20,40,60,80 and100 A g^-1,respectively.When the potential is adjusted from 0 to 0.55,its specific capacitance is 1089.8,1035.5,996.4,887.3,829.1,774.5,741.8,745.5 F g^-1 at high current densities of 2,5,10,20,40,60,80 and 100 A g^-1,respectively.It is notable that even under the highest current density of 100 A g^-1,the nanoporous ZnWO₄nanoparticles electrode still shows an specific capacitance of 745.5 F g^-1(74.8%of the capacity retention from 10 to 100 A g^-1 and 96.3%of the capacity retention from 60 to100A g^-1),and it is even higher than 80 A g^-1 which specific capacitance is 741.8.It is found that the zinc tungstate supercapacitor prepared by electrospinning is a kind of porous zinc tungstate particles.The morphology is rare in electrostatic spinning.