Lithium-Ion Electrode Assembly With Porous Adhesive Interface
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Solution Overview
Problem
Conventional lithium ion secondary batteries face issues with insufficient adhesion between the separator and electrodes, leading to partial detachment, wrinkles, and reduced ionic conductivity, which can cause internal short circuits and capacity loss.
Innovation Solution
A lithium ion secondary battery design featuring a porous layer on the negative electrode with a polymer binder and inorganic fine particles, bonded to a positive electrode via an ionic conductive polymer adhesive portion, with an area ratio of 0.02% to 50% on the positive electrode surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an adhesive is applied to the interface between the electrode and the separator to supplement adhesive force, then adhesion durability is improved, but ionic conductivity between electrodes decreases causing capacity loss
Solution Approach 1:
The patent introduces a porous layer as an intermediary component between the negative electrode and separator. This porous layer includes inorganic fine particles dispersed in a polymer binder, creating a transition zone that simultaneously provides adhesion to the electrode and maintains ion transport pathways. The porous structure allows electrolyte penetration and ion conduction while the polymer binder ensures mechanical bonding, thus resolving the contradiction between adhesion durability and ionic conductivity.
2Temperature
If a separator comprising a separator substrate and inorganic coating layer is used, then thermal stability is improved, but adhesive force between separator and electrode becomes insufficient causing partial detachment and wrinkles
Solution Approach 1:
The patent employs a composite porous layer structure consisting of inorganic fine particles (such as Al2O3, SiO2, TiO2, or ZrO2) dispersed in a polymer binder matrix. This composite material combines the thermal stability of inorganic particles with the adhesive properties of the polymer binder, achieving both high-temperature resistance and strong bonding to the electrode, thereby resolving the contradiction between thermal stability and adhesive force.
3Temperature
If the separator is constructed using only an inorganic coating film to eliminate the polyolefin separator substrate, then thermal stability is improved, but adhesive force with electrodes remains insufficient and insulating properties become extremely low causing internal short circuits
Solution Approach 1:
The patent creates a composite porous layer that combines inorganic fine particles with a polymer binder. The inorganic particles provide thermal stability and insulating properties, while the polymer binder ensures adequate adhesive force to the electrode. This composite structure prevents internal short circuits by maintaining proper insulation while achieving sufficient adhesion, resolving both the adhesion deficiency and insulating property issues of pure inorganic coating films.
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 design achieves excellent adhesion durability without impairing ionic conductivity, enhancing the battery's performance and safety by preventing detachment and maintaining capacity.
Implementation Method 1
the adhesive portion includes an ionic conductive polymer
Implementation Method 2
a positive electrode portion bonded onto the porous layer through an adhesive portion
Data Source
AI summary
A lithium ion secondary battery includes a negative electrode portion, a porous layer formed on at least one surface of the negative electrode portion, and a positive electrode portion. The porous layer includes a polymer binder and inorganic fine particles dispersed on the polymer binder. The positive electrode portion is bonded onto the porous layer through an adhesive portion arranged continuously or discontinuously. The adhesive portion includes an ionic conductive polymer, and a ratio of an area occupied by the adhesive portion ranges from 0.02% to 50% based on an area of one surface of the positive electrode portion. A lithium ion secondary battery including an electrode assembly which has excellent adhesion durability without impairing ionic conductivity between electrodes is also provided.