Research On Additive Manufacturing Of Carbon-based Anode Materials For Lithium Ion Batteries And Its Electrochemical Performance

With the scientific progress and social development,the long-term loss of fossil energy has increased,and environmental pollution has become increasingly serious.The use of renewable energy such as solar,wind,and tidal energy and the development of their energy storing device can effectively alleviate this phenomenon.As one of the most promising electrochemical energy storage devices,lithium-ion batteries occupy the market with recyclability and high voltage.However,higher requirements for energy density limit its further development.Pneumatic jetting additive manufacturing technology provides a new process method for the formation of lithium-ion battery anode materials,breaks the limitation of traditional coating technology,opens up a fast,accurate,and high-energy-density new way for the complex structure of electrode materials,and has broad prospects in the field of lithium-ion battery manufacturing.This study combines graphite anode slurry with pneumatic jetting additive manufacturing technology.Oily solvent system was selected,and the slurry viscosity curve was used to determine that anode slurry is a non-Newtonian fluid.By optimizing the solid volume fraction and dispersion time,a uniform,stable and printable graphite anode paste was prepared.Based on Carreau model,H-B model and Cross model,substituting the actual viscosity,and the 1st Opt software was used to fit the empirical formula.The analysis shows that Carreau model can accurately describe the variation trend of viscosity within a certain shear rate range.Thus,the constitutive equation of the anode slurry was obtained.Fluent was used to establish a flow model of anode electrode slurry in the barrel and nozzle.Under different nozzle structures,jet pressure,nozzle diameters,the flow field distribution and flow rate were analyzed,and the changing rule of width with different printing parameters was obtained,which were combined with experiments to determine the printing parameters of graphite slurry.The influence to electrochemical property of forming parameters and modification methods of graphite anode slurry were explored.The graphite slurry was formed on the copper foil by pneumatic jetting forming,and were assembled into a coin lithium-ion battery for electrochemical performance.The effect of printing structure and interval on the electrochemical performance of additive manufacturing were studied.Compared with the coating process.the influence of number of printing layers on the electrochemical performance of lithium-ion batteries were discussed.Large surface area electrode structure was prepared,and the area capacity is achieved as 1.7 m Ah cm^-2.To increase specific capacity,the graphite was mixed and doped with Na Cl by ball milling and calcining.G-N-850℃ has higher capacity and rate performance.After forming with additive manufacturing,the area capacity reaches 2.7 m Ah cm^-2.Aiming at the non-renewable and low capacity of graphite anode,rice husks,a agricultural waste were used as raw materials to replace commercial graphite anode to prepare cellulose carbon,and K₂CO₃ was used to activate amorphous carbon.The structure and morphology of materials were characterized by XRD,Raman,SEM,TEM and BET,and electrochemical performance was analyzed.When the mass ratio of cellulose carbon to K₂CO₃ is 1:1,RHC-K-1 has a more uniform mesoporous structure,with a specific surface area of 1658.557 m² g^-1 and a pore distribution between 2-8 nm,the capacity remains at 518.6 m Ah g^-1 after 100 cycles at 0.2C.The printing path and substrate were improved.Printing by a single line first and then different layers was formed on the copper form substrate.The three-layer printing thickness reaches0.58mm,and the area capacity reaches 1.5 m Ah cm^-2.The electrochemical test shows that when compared with the traditional coated electrode,electrode with large surface area structure formed by additive manufacturing has a higher area capacity,thereby increasing its energy density,which proves the development prospect of additive manufacturing in the field of lithium ion battery forming.