Negative Electrode Slurry Composition for Higher Layer Compressibility
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Solution Overview
Problem
Existing methods for producing negative electrodes for secondary batteries, particularly lithium ion secondary batteries, face challenges in enhancing the compressibility of the negative electrode active material layer, especially when using aqueous slurry, as the special binder compositions described in prior patents are not suitable for this method.
Innovation Solution
A method involving the application of a slurry comprising a negative electrode active material, a first binder (such as carboxymethyl cellulose or its metal salt), a second binder (such as styrene-butadiene rubber or its derivative), water, and dimethyl sulfoxide (DMSO) onto a negative electrode current collector, followed by drying to form a negative electrode active material layer. The amount of DMSO is crucial, ranging from 2.5 to 10.0 mass % with respect to the negative electrode active material, and optionally including a pressing step to enhance the layer's density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a special binder composition is used to enhance compressibility of the negative electrode active material layer, then compressibility is improved, but the binder composition is not suitable for aqueous slurry method
Solution Approach 1:
The invention changes the chemical composition parameters of the binder system by introducing dimethyl sulfoxide (DMSO) as a key component in the aqueous slurry. The specific parameter range of DMSO (2.5-10.0 mass% relative to active material, or 10-400 mass% relative to binder) transforms the binder's properties to achieve both compressibility enhancement and aqueous slurry compatibility simultaneously
Solution Approach 2:
The invention creates a composite binder system combining multiple components: binder (1-10 parts by mass relative to active material), dimethyl sulfoxide (2.5-10.0 mass% relative to active material), and water. This composite formulation integrates the advantages of different materials to achieve both high compressibility and suitability for aqueous processing methods
2Quantity of substance
If the density of the negative electrode active material layer is increased to enhance battery performance, then energy density is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The invention modifies the slurry composition parameters by incorporating DMSO in specific amounts (2.5-10.0 mass% relative to active material), which changes the physical and chemical properties of the slurry to enable better packing density and compressibility during the standard coating and drying process, achieving high density without adding complex manufacturing steps
Solution Approach 2:
Dimethyl sulfoxide acts as an intermediary substance in the slurry that facilitates better distribution and packing of the active material particles. It mediates between the binder and active material, enabling enhanced density achievement through standard manufacturing processes without requiring additional complex equipment or steps
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method effectively enhances the compressibility and density of the negative electrode active material layer, leading to improved performance and energy density in secondary batteries, particularly lithium ion secondary batteries.
Implementation Method 1
A method for producing a negative electrode, which is capable of enhancing compressibility of a negative electrode active material layer
Implementation Method 2
drying the applied slurry to form a negative electrode active material layer
Data Source
AI summary
Provided is a new method for producing a negative electrode, which is capable of enhancing compressibility of a negative electrode active material layer. A method for producing a negative electrode disclosed herein includes: applying slurry including a negative electrode active material, a first binder, a second binder, water, and dimethyl sulfoxide, onto a negative electrode current collector; and drying the applied slurry to form a negative electrode active material layer. The first binder is at least one of carboxymethyl cellulose and a metal salt of carboxymethyl cellulose. The second binder is at least one of styrene-butadiene rubber and a derivative of styrene-butadiene rubber. An amount of the dimethyl sulfoxide is 2.5 mass % or more and 10.0 mass % or less with respect to the negative electrode active material.