Preparation And Electrochemical Properties Of Si / C And SnO 2 / C For Lithium Ion Batteries

Compared with ordinary batteries, lithium-ion batteries have high energy density, high power density, long cycle life and a wide operating temperature range, etc. They have been widely used in the portable electronic devices, electric vehicles and aerospace and other fields gradually. In general, the major components of the lithium ion battery have:the positive electrode, separator, negative electrode, electrolyte, current collector and so on. The advantages and disadvantages of these components determine the performance of lithium-ion battery. The anode material as a key component of the overall performance of lithium plays an important role. Therefore, the study on high electrochemical performance parameters of the lithium-ion battery anode material in lithium-ion batteries field attracts widespread attention. Commercial lithium ion battery uses graphite-like carbon material as the negative electrode, but the theoretical capacity of carbon is limited to 372 mA·g·1, resulting in an overall capacity of the battery whose capacity is low. Carbon-supported metal anode composite material not only have the high-capacity ratio of metal, good conductivity, but also benefit from the buffering effect of carbon materials on metal volume expansion in the charge-discharge process, which can effectively improve the cycle performance of the material, so it is a species very promising anode material for lithium batteries.This paper introduces the research progress of lithium battery anode materials, also prepared nano silicon/carbon composite microspheres and tin oxide/carbon composite carbon-coated material, and then prepared a battery pole piece, assembled into a CR2032 coin cell, researched its electrochemical properties. By XRD, SEM, TEM and other characterization of the composition and morphology of the materials were characterized. The electrochemical properties were tested by using constant current charge and discharge、CV testing. The main results are as follows:1, By a modified condensation reaction between 2,4-dihydroxybenzoic acid and formaldehyde as organic material, adding a certain amount of non-ionic surfactant poly (ethylene-propylene-ethylene glycol) (F108) triblock segment polymer, a small amount of L-lysine as a catalyst, nano-silicon particles, then got the nano Si/C composite microspheres coated with carbon material, prepared by the wash process with water and heat treatment. Controling addied quality nanometer silicon, different samples were prepared to explore its effects on morphology and properties of the material. SEM shows the composite microspheres have a good shape, uniform size. Constant current charging and discharging and CV tests show that when the addition of nano silicon content of 8%, the preparation of nano:Si/C carbon coating composite material in the capacity and cycle properties is better. When the voltage range of 0.005-3.00 V, current density is 100 mA·g-1, the first charging capacity was 532.0 mA·g·1, the reversible capacity of the 100th cycle was 321.8 mA·g·1, the capacity retention rate was 60.5 percent.2,Adopting the chemical precipitation, and by further hydrothermal reaction, prepared nano tin oxide particles,the particle size analysis by TEM shows about 5 nm; By a modified condensation reaction between 2,4-dihydroxybenzoic acid and formaldehyde as organic material, adding a certain amount of tin oxide nano-particles, then through the wash process with water and heat treatment step of preparing a nano-SnO2/C carbon-coated composite material. By controling the quality of the Tin Oxide particles to explore the impact on the material morphology and properties of different samples. Research shows that when nano-tin oxide content is 40%, the nano-SnO2/C carbon-coated has a good electrochemical properties. When the voltage is 0.005-3.00 V, current density is 100 mA·g-1, the initial reversible capacity was 825.2 mA·g·1, the reversible capacity of the 100th cycle was 593.2 mA·g·1, and the capacity retention rate was 71.9%.