High-capacity silicon-carbon composited anode material, preparation method and application thereof

Abstract

The invention relates to a high-capacity silicon-carbon composited anode material, a preparation method and application thereof, wherein the silicon-carbon composited anode material comprises the following compositions in parts by weight: 1-30 parts of silicon materials, 30-120 parts of carbon materials, and 10-80 parts of pyrolytic carbon. The silicon materials in the silicon-carbon composited anode material disclosed by the invention are uniformly adhered to the surfaces of carbon material particles, and then the outer layers of the carbon material particles are wrapped with the pyrolytic carbon, therefore, the silicon-carbon composited anode material disclosed by the invention has the advantages of lower first irreversible specific capacity, higher specific capacity, excellent cycle performance, low preparation cost and the like; and the first discharge capacity of the silicon-carbon composited anode material is greater than 450 mAh.g<-1> under a 0.2 C discharge ratio, and the retention rate of capacity after 50 cycles is more than 80%.

Description

technical field [0001] The invention belongs to the field of lithium-ion battery materials, and in particular relates to a high-capacity silicon-carbon composite material, a preparation method and an application thereof. Background technique [0002] Graphite anode materials have high cycle efficiency and good cycle performance, and have been widely used in the preparation of lithium-ion battery anode materials. However, graphite-based negative electrode materials have low lithium storage capacity, and the theoretical specific capacity is only 372mAh g -1 and other defects. For this reason, novel anode materials need to be developed to improve the electrochemical performance of lithium-ion batteries. [0003] At present, research on high-capacity composite anode materials (Wang Baofeng, Yang Jun et al. Silicon / carbon composite anode materials for lithium-ion batteries [J], ACTA CHIMICA SINICA, 2003, 61(10): 1572-1576) mainly focuses on silicon (Theoretical capacity is 420...

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Problems solved by technology

[0003] At present, research on high-capacity composite anode materials (Wang Baofeng, Yang Jun et al. Silicon / carbon composite anode materials for lithium-ion batteries [J], ACTA CHIMICA SINICA, 2003, 61(10): 1572-1576) mainly focuses on silicon (Theoretical capacity is 4200mAh·g -1 ), Sn (theoretical capacity 990mAh·g -1 ), Sb (theoretical capacity 536mAh·g -1 ), Al (theoretical capacity 400mAh·g -1 ) and other metal composite materials or non-metallic composite materials that can reversibly delithiate and deintercalate lithium. The reversible delithiation and lithium intercalation capacity of these composite negative electrode materials is much greater than that of graphite, but they need to experience serious volume expansion during the cycle of lithium intercalation and delithiation. and shrinkage, leading to poor electrical contact between the active material and the current collector, which in turn leads to poor capacity and cycle performance of the material, and a short battery life, which hinders the practical application of these composite materials

For this reason, researchers have adopted some improved methods to increase the capacity of composite negative electrode materials and improve cycle stability, for example, Wang Baofeng, Yang Jun, etc. (Silicon / carbon composite negative electrode materials for lithium ion batteries [J], ACTA CHIMICA SINICA, 2003, 61 (10): 1572-1576) discloses a method for preparing and reducing the particle size of alloy particles, which controls the particle size range of alloy particles to submicron or nanoscale to reduce the relative volume effect of the alloy; CN1402366A discloses A composite material is proposed, which contains SiOx, Si-Ag, Si-Al, Sn-Cu and other components, wherein 0<x<2, the composite material adopts multi-phase doping composite, step-by-step Prepared by completing the method of intercalating and removing lithium; Yoshio, M. et al. (Electrochem.Soc, 2002, 149 (A1598.)) used vapor deposition to coat carbon on the surface of silicon to improve the conductivity and cycle performance of the composite material ; but this method has higher requirements for equipment, is difficult to obtain products with uniform performance, and has defects such as difficulties in large-scale production

CN101439972A discloses a silicon-carbon composite material containing nano-silicon / carbon nanotube composite particles and amorphous carbon, the amorphous carbon is coated on the surface of the composite particles, and the battery made of the negative electrode prepared by the composite material has a lower For the first time, irreversible specific capacity, high specific capacity and excellent cycle performance, but the raw material carbon nanotubes have defects such as resource shortage and high price, which lead to high manufacturing costs of composite materials and affect their practicability and industrialization

The silicon-carbon composite material prepared by this method has high capacity and good cycle performance, but its preparation process is relatively complicated.

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