A kind of water-based conductive binder suitable for lithium-ion battery silicon-based negative electrode material and preparation method thereof

Abstract

The invention relates to an aqueous conductive binder suitable for silicon-based negative electrode materials of lithium ion batteries and a preparation method thereof. The preparation method includes the following steps: (1) preparing raw materials; In the process, the crosslinkable precursor acrylic monomer, chitosan and sodium styrene sulfonate are dissolved in deionized water, the first initiator is added, and the reaction is carried out in a nitrogen atmosphere and under the conditions of 70 ℃ ~ 90 ℃ for 2 to 4 hours, Synthesize the intermediate solution; (3) according to the proportion of parts by mass, add 3,4-ethylenedioxythiophene to the intermediate solution obtained in step (2), then add the second initiator dropwise, and maintain at 30-40 ℃, polymerize for 3-6 hours to obtain the desired water-based conductive adhesive. Compared with the prior art, the present invention has the advantages of high electrical conductivity, high adhesion, moderate viscosity and good dispersibility.

Description

technical field [0001] The invention relates to the technical field of lithium-ion secondary batteries, in particular to a water-based conductive binder suitable for silicon-based negative electrode materials of lithium-ion batteries and a preparation method thereof. Background technique [0002] Due to its high energy density, good cycle performance, low self-discharge rate, environmental protection and no pollution, lithium-ion batteries have been widely used in portable electronic devices such as mobile phones and notebook computers, and are gradually being used in electric vehicles, aerospace and storage Energy systems and other fields. New application scenarios put forward higher requirements on the specific capacity, rate characteristics, and cycle life of lithium-ion batteries. The performance of lithium-ion batteries depends largely on the positive and negative electrode materials that make up the battery. The actual specific capacity of traditional graphite anode ...

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Problems solved by technology

However, due to the self-lubricating properties of graphite, it is not easy to adhere; and the used binder and dispersant lack electrical conductivity, so it is easy to cause a large internal resistance of the pole piece, which is not conducive to the performance of the battery; the patent application number is CN201510737797. 8 (Notice No. CN105406039A)’s invention patent “A Si-Carbon Negative Electrode Slurry and Its Preparation Method” uses carbon black Super-p and single-arm carbon nanotube suspension emulsion as conductive additives, but the single-arm carbon nanotube has a large surface energy. , very easy to agglomerate, the conductivity effect depends on the dispersion process and is not stable enough, which in turn affects the electrochemical performance of the pole piece

[0005] In addition, the existing water-based binders for negative electrodes of lithium-ion batteries, such as styrene-butadiene rubber emulsion, polyacrylic acid polymers, etc., must be used in conjunction with conductive agents and dispersants due to their low electrical conductivity; poly(3,4-ethylene diethylene Oxythiophene)-polystyrene sulfonic acid (hereinafter referred to as PEDOT: PSS) is a conductive polymer with good water solubility, which is often used as the matrix of solid conductive hydrogel, but it is directly mixed with the polymer binder in the solution state. When, usually due to the change of the solution environment, the unstable agglomeration and sedimentation

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