Flexible Battery Electrodes Using Plasticizer Binders
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Solution Overview
Problem
Lithium ion battery electrodes face challenges with mechanical stress and loss of contact between active material particles due to volume expansion during lithiation, particularly with metallic and semimetallic materials, and existing binders like carboxymethylcellulose exhibit poor processability and adhesion to current collectors.
Innovation Solution
Aqueous paste for producing lithium ion battery electrodes containing aliphatic polyester or hydroxycarboxylic ester plasticizers, such as triethyl citrate or glyceryl triacetate, which improves processability and adhesion without compromising electrochemical properties, combined with a polysaccharide-based binder like sodium carboxymethylcellulose.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If metallic and semimetallic active materials (e.g., silicon, tin, antimony) are used to achieve high storage capacity, then specific charge is improved, but volume expansion during lithiation causes mechanical stress and loss of contact between particles
Solution Approach 1:
The patent applies beforehand cushioning by incorporating a binder into the electrode structure prior to lithiation. This binder acts as a cushioning matrix that accommodates the volume expansion of metallic and semimetallic active materials during lithiation, preventing mechanical stress and loss of contact between particles. The binder is applied in advance to create a flexible framework that can absorb expansion forces.
Solution Approach 2:
The patent employs composite materials by combining metallic or semimetallic active materials with a binder to form a composite electrode structure. This composite approach allows the electrode to benefit from the high storage capacity of metallic materials while the binder provides mechanical stability and flexibility to accommodate volume changes during charge-discharge cycles.
2Stability of the object's composition
If carboxymethylcellulose binder is used to ensure mechanical stability, then electrode structure is maintained, but adhesion to current collectors is poor and processability is limited
Solution Approach 1:
The patent applies parameter changes by modifying the binder system from conventional carboxymethylcellulose to a polymeric binder with specifically adjusted parameters: molecular weight between 10,000 and 1,000,000 g/mol, and glass transition temperature between -50°C and 50°C. These parameter adjustments improve both adhesion to current collectors and processability while maintaining mechanical stability.
Solution Approach 2:
The patent applies local quality by optimizing different regions of the binder system for different functions. The binder is designed with specific molecular weight and glass transition temperature characteristics that provide strong adhesion at the electrode-current collector interface while maintaining appropriate mechanical properties in the bulk electrode structure for easy processing.
3Stability of the object's composition
If conventional binders are used to maintain electrode structure, then mechanical stability is achieved, but adhesion to current collectors is insufficient
Solution Approach 1:
The patent applies parameter changes by selecting a polymeric binder with optimized molecular weight (10,000-1,000,000 g/mol) and glass transition temperature (-50°C to 50°C). These parameter changes enhance the adhesion strength between the electrode and current collector while maintaining the mechanical stability of the electrode structure during volume expansion.
Data Source
Figure 1A~1C
Figure 2A~2B
Figure 3A~3B
AI summary
A paste for producing electrodes and a process for producing electrodes using such a paste and also electrodes and batteries produced therewith are described. The paste contains particles of at least one electrochemically active material, a binder, water as solvent and at least one plasticizer having an ester-like nature.