The Study Of Composite Anode Material In Lithium Ion Batteries

Lithium ion battery attracts intensive and is widely in many fields after being commercialized. The anode material is one of the three most critical factors of lithium ion battery electrochemical performance. In order to improve the capacity of lithium storage capacity and the reversibility of lithiation and delithiation, making the electrochemical performance of lithium ion battery to meet the need of usage, we have done plenty of researches about anode materials. Nano TiO₂ is an excellent anode material due to due to its rich source, nontoxicity, and environmentally friendly. What’s more, the working voltage is high, which is very safe. However, the theoretical specific capacity and electronic conductivity of TiO₂ is low. Silicon is a new high capacity anode material with low electronic conductivity. In the process of lithiation and delithiation, the volume expansion of Silicon is large, leading the material falls from the collector. In order to address the challenges of these anode materials, we prepared the TiO₂/SnO₂ composite material and Si-Sn composite material. What’s more, we characterized and analyzed the physical properties and electrochemical properties of composite materials.We prepared the nano mesoporous TiO₂ material by a sol-gel and solvothermal method. The SEM,XRD,CV and constant-current charge-discharge were used to analyze the nano mesoporous TiO₂ material. The structure-directing agent and solvent C₂H₅ OH in the preparation of TiO₂ material were discussed to explore the impact of TiO₂ material morphology, structure and electrochemical properties. Modified nano mesoporous TiO₂ material by adding the TiO₂ prepared in the optimal situation as precursors, using SnCl₄?5H₂O as tin sources, we fabricated TiO₂/SnO₂ composite material. XRD, XPS, XRD, EDS mapping, BET and BJH were used to confirm the constitution of TiO₂/SnO₂ composite material. CV and constant-current charge-discharge were used to analyse the electrochemical performance of TiO₂/SnO₂ composite material. At the rate of 1C, the TiO₂/SnO₂ composite materials show discharge capacities of 436.5 mAh/g at the 850 th cycles respectively under the same conditions. The discharge capacities of the TiO₂/SnO₂ composite materials are 35.6% higher than TiO₂ materials. The TiO₂/SnO₂ composite materials exhibit 119.7 mAh/g and discharge capacity at 10 C after 2000 cycles, respectively. The discharge capacities of the TiO₂/SnO₂ composite materials are 114.5% higher than TiO₂ materials, respectively.Modified 1μm Silicon powder by using electroless plating, we prepared Si-Sn composite materials. The temperature and time of electroless plating were discussed to explore the impact of composite materials morphology, crystal forms and electrochemical properties. SEM, XRD, EDS were used to confirm the constitution of Si-Sn composite material. CV and constant-current charge-discharge were used to analyse the electrochemical performance of Si-Sn composite material. The discharge capacities of the Si-Sn composite materials prepared by 75 ℃ and 5 min are 1889.7% higher than 1μm Silicon powder after 10 th cycles respectively under the same conditions.