Lib Structure And Properties Of Anode Material

The lithium-ion batteries posses many advantages such as high-voltage, high energy density, long cycle-life, little effect of memory and better environment benefits etc.LiB compound as the anode for lithium ion rechargeable batteries are explored. The electrochemical characteristics are studied and the a.c. impedance is also measured. The influence of extraction-insertion of lithium ions from-into the LiB compound on the structure and microstructure is studied by XRD and SEM.There are three discharging plateaus, 0.46V, 0.69V and 0.80V(vs.Li+/Li), in discharging curves of the LiB compound. Its discharging capacity is up to 660mAh/g; and the lithium ions from the 0.46V, 0.69V discharging plateaus have the reversibility ,and its total specific capacity is 274 mAh/g. The lithium ions from the 0.80V discharging plateaus is irreversible.XRD results show that when LiB compound is in Li deficient state, the lattice constants of the compound will increase stage by stage, and with the insertion of lithium ions into compound the lattice constants can come back. The LiB compound is Li_7.08B₆ ,which is the vicinity of Li₇B₆.It is showed that the crystal structure of the compound is stable under 0.8V plateau by XRD and a.c. impedance test. There is passivation layer (SEI film) on the surface of the LiB electrode. Over 0.8V plateau, the passivation layer can not be found. The reversibility mechanism of LiB compound is extraction-insertion.Finally, the compound by the method of melting using B₄C as the substitute of B is prepared , and its structure and electrochemical properties are also studied..