Negative Electrode Composition for Thick-Film Crack Resistance
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Solution Overview
Problem
The increase in thickness and coating speed of the negative film layer in secondary batteries leads to cracking during drying, which reduces yield, increases production costs, and deteriorates the performance and safety of the battery.
Innovation Solution
A negative electrode composition comprising a plasticizer with a POSS-containing block copolymer or a polyester containing a —[O—CH(CH3)—C(═O)]— structural unit, combined with an organic solvent with a boiling point of 160° C. to 250° C., to enhance flexibility and reduce intermolecular forces, thereby minimizing cracking and improving electrolyte infiltration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the thickness of the negative film layer is increased to improve energy density, then the energy density is improved, but the negative film layer is prone to break apart during drying
Solution Approach 1:
The patent changes the chemical composition parameters of the film layer by incorporating specific plasticizers (POSS-containing block copolymers or polyesters with —[O—CH(CH3)—C(═O)]— structural units) to modify the physical properties of the film, enabling it to maintain integrity at increased thicknesses
Solution Approach 2:
The patent creates a composite material system by combining the negative active material with specially designed plasticizers that have flexible molecular structures, resulting in a film layer that兼具 high thickness and crack resistance
2Productivity
If the coating speed is increased to improve production capacity, then the productivity is improved, but the negative film layer is prone to break apart during drying
Solution Approach 1:
The patent modifies the rheological parameters of the coating material by adding plasticizers that reduce intermolecular forces, allowing the film to withstand the mechanical stresses of high-speed coating and subsequent drying without cracking
3Quantity of substance
If the thickness of the negative film layer is increased to improve energy density, then the energy density is improved, but the infiltration of electrolytic solution becomes difficult and kinetics deteriorate
Solution Approach 1:
The patent changes the chemical composition of the film layer by incorporating plasticizers with functional groups that enhance electrolyte compatibility, enabling the film to maintain both increased thickness and improved electrolyte infiltration capability
Solution Approach 2:
The patent creates a porous or micro-channeled structure within the thick film layer through the use of plasticizers that reduce intermolecular bonding, facilitating electrolyte penetration deep into the film while maintaining high active material content
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
The solution effectively reduces the brittleness and cracking of the negative film layer, enhances lithium-ion conductivity, and improves the cycle and rate performance of the secondary battery without adversely affecting electrolyte performance.
Implementation Method 1
diffused into a molecular network of additives such as a polymer binder and a carboxymethyl cellulose (CMC) thickener
Implementation Method 2
The polar group that contains a lone electron pair is highly hydrophilic, and can ensure high solubility of the plasticizer in water
Implementation Method 3
Even if a residue of the plasticizer remains in the electrode plate
Data Source
AI summary
A negative electrode composition includes a negative active material and a plasticizer. The plasticizer includes a first plasticizer. The first plasticizer includes at least one of a POSS-containing block copolymer or a polyester containing a —[O—CH(CH3)—C(═O)]— structural unit.