PEDOT: PSS/CMC composite binder and preparation method and application thereof

Abstract

The invention relates to the field of lithium ion batteries, and discloses a PEDOT: PSS / CMC composite binder and a preparation method and application thereof. The composite binder is prepared from poly (3, 4-ethylenedioxythiophene): polystyrene sulfonate / hydroxymethyl cellulose (PEDOT: PSS / CMC) in a cross-linked state; the prepartion raw materials of the composite binder includes PEDOT: PSS and CMC in a mass ratio of (0.1-10): 1. When the composite binder is used for preparing a silicon-based negative electrode of a lithium ion battery, functional groups in the binder can be effectively bondedwith silicon, so that the bonding force with a silicon-based material is improved, a more stable SEI film can be formed to reduce direct contact with an electrolyte, the amount of byproducts is reduced, and the overall structure of the electrode is more stable. The silicon-based negative electrode of the lithium ion battery prepared from the binder can keep complete morphology after circulation,and the cycling stability of the battery can be improved.

Description

technical field [0001] The invention belongs to the technical field of negative electrode materials for lithium ion batteries, and in particular relates to a PEDOT:PSS / CMC composite binder and a preparation method and application thereof. Background technique [0002] In recent years, with the rapid development of the new energy industry, lithium-ion batteries have been widely used in the fields of electronic products, power batteries and energy storage due to their advantages such as high energy density and long cycle life. However, with the continuous improvement of battery performance requirements for electric vehicles and hybrid vehicles, the development of lithium-ion batteries with high power and high energy density has become an urgent problem to be solved. The positive and negative electrode materials of lithium-ion batteries are closely related to the performance of the battery. At present, the energy density of commercial graphite anode materials has reached the b...

AI Technical Summary

Problems solved by technology

At present, the energy density of commercial graphite anode materials has reached the bottleneck, and it is difficult to have room for improvement, while silicon-based anode materials have a high theoretical specific capacity (Si: 4200mAh g -1 ), low lithium-deintercalation potential, and abundant reserves are considered to be the most promising next-generation lithium-ion battery anode materials that can replace graphite anodes.

[0003] The silicon-based negative electrode provides capacity through the process of alloying and dealloying with lithium ions during charge and discharge, and this process will produce a huge volume expansion (about 300%), which will lead to many problems, such as: 1. Huge volume expansion will lead to crushing and powdering of silicon-based material particles; 2. A large amount of pulverized material will peel off from the current collector, resulting in capacity attenuation and poor cycle performance; 3. Repeated volume changes during charge and discharge will make the material The SEI film (solid electrolyte interfacial film) on the particle surface is constantly broken and reconstructed, which will consume a large amount of active lithium, which will reduce the capacity retention and coulombic efficiency

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