Preparation And Characterization Of Metal Oxide/Graphite Negative Electrode Materials For Lithium-ion Battry

With the development of lithium ion battery industry, more and more researcherspay attention to the development of anode materials. Graphite anode materials occupythe dominant position, but there are still many electrochemical performance problems.The paper prepared metal oxide/graphite negative electrode materials by two differentmethods. XRD, SEM, TEM and Raman were used to characterize the materials’structure and morphology. It was electrochemical performance tested.The paper made oxidation treatment to graphite firstly. Ultimately the bestoxidation solution for the graphite is that using melioration Hummers method, oxidantdosage mgraphite/mKMnO4is1:3, intermediate-temperate reaction time is1h. Afteroxidation treatment, graphite layer introduced a lot of oxygen-containing functionalgroups. The interlayer spacing expanded from0.336nm to0.766nm.The NiO/graphite negative electrode materials were prepared by directprecipitation method and high-temperature calcination. Structure and morphologycharacterization results showed that graphite layer and NiO is composite of theNiO/graphite negative electrode materials. Grain size of NiO is about24.6nm, but ithad reunion phenomenon. Graphite layer appeared cracks and debris. Theelectrochemical test results showed that the circulating discharge specific capacity is337mAh·g^-1and the capacity retention ratio is57.4%（except for the first cycle） after50cycle at0.1C low rate, it is less than the capacity of graphite. The circulatingdischarge specific capacity is138mAh·g^-1after10cycle at1C high rate, that is betterthan66mAh·g^-1of graphite.The SnO₂/graphite negative electrode materials were prepared by in-situ liquidphase deposition method and high-temperature calcination. The structure andmorphology characterization results showed that graphite layer and SnO₂is compositeof the SnO₂/graphite negative electrode materials. Grain size of SnO₂is about10.8nmand the particle distributed uniform and not had reunion phenomenon. The graphitekept good layer structure. The electrochemical test results showed that the circulatingdischarge specific capacity is492mAh·g^-1and the capacity retention ratio is80.6%（except for the first cycle） after50cycle at0.1C low rate. The circulating dischargespecific capacity is178mAh·g^-1after10cycle at1C high rate. The electrochemicalperformance of graphite has improved at both low and high rate.