The Investigations On Technics And Properties Of Carbonaceous Anode For Lithium-ion Batteries And 18650 Batteries Of High Capacity

The effects of factors, such as electrode, electrolyte and technics of preparation of electrode on carbonaceous anode and the interface between anode and electrolyte(SEI) were investigated by testing simulated half-cells assembled (Li metal|separator(organic electrolyte)|carbonaceous anode) in terms of Constant Current(CC), Cyclic Voltammetry(CV), Electrochemical Impedance Spectra(EIS), Scanning Electron Microscope(SEM) and Differential Scanning Calorimetry(DSC). The results show that carbonaceous mesophase spherules (CMS) is an excellent anode material for lithium-ion battery, properties of half-cells in which water-based binder(Binder A) was used are good, and the best when the content of water-based binder is 6%. Water-based binder (Binder A) can be a good substitution of PVDF, but its requirements to technics of preparation of electrode is stricter compared to PVDF, for example, density of volume and compression mode of electrode is critical to the properties of cells. The conductive additive of carbon black to CMS anode can reduce the interner resistance and improve the performances of charge at a large current and cycle, but enhance initial irreversible capacity and depress practical reversible discharge/charge capacity. The investigations to the interface between anode and electrolyte show that the compatibility of electrolyte (1mol/L LiPF6/(EC+DEC+EMC))to CMS anode is the best when the ratio of mixed solvent (EC:DEC:EMC) is 1:0.5:0.5. And the impedance of interface between anode and electrolyte increases along with the increase of cycle number and the enhancement of content of lithium ion in electrode. The onset temperature of thermal decomposition of interface SEI of electrode in the state of full charge is low and the thermal stability of SEI is bad in contrast to that in the state of zero charge.The studied anode system is applied to 18650 lithium-ion batteries. Through further investigating and summarizing, an excellent technical flow is fixed and 18650 lithium-ion batteries of high capacity are produced by means of a middle-try product line. And they are tested. The result shows that the special capacity of battery is more than 2300mAh, interner resistance is less than 70m?, and the performances of high/low temperature, safety and adaptation to environment are uniform to GB/T18287-2000.