Battery Separator Adhesive Layer for Wet-Dry Adhesion Balance
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Solution Overview
Problem
Lithium batteries face challenges in achieving both excellent wet and dry adhesion between electrodes and separators, which is crucial for maintaining battery shape and assembly processability, especially under high-temperature and high-capacity conditions, and existing methods fail to evaluate and optimize both adhesion types effectively.
Innovation Solution
A lithium battery design incorporating a separator with a porous substrate and an adhesive layer containing ceramic particles and a polyvinylidene fluoride-based binder at a specific mixing ratio, along with controlled press conditions, to achieve optimized dry and wet adhesion, as represented by an adhesion ratio of 0.05 to 1.0, ensuring improved adhesion and heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separator with adhesive layer is used to improve adhesion between electrodes, then wet adhesion is improved, but dry adhesion deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the adhesive layer by incorporating ceramic particles (alumina, silica, or boehmite) at specific weight ratios (30-70 wt%) combined with binder polymers. This parameter adjustment enables the adhesive layer to achieve both wet adhesion (through polymer bonding) and dry adhesion (through ceramic particle friction and mechanical interlocking), resolving the contradiction between the two adhesion types.
Solution Approach 2:
The patent creates a composite adhesive layer material combining organic binder polymers (polyvinylidene fluoride, carboxymethyl cellulose, or styrene-butadiene rubber) with inorganic ceramic particles. This composite structure provides dual functionality: the polymer matrix ensures wet adhesion while the ceramic particles contribute to dry adhesion, simultaneously improving both previously conflicting properties.
2Quantity of substance
If high-capacity electrodes are used to increase energy density, then battery capacity is improved, but heat resistance deteriorates
Solution Approach 1:
The ceramic particles in the adhesive layer serve as thermal intermediaries between the high-capacity electrodes and the separator. Materials like alumina and boehmite have high thermal stability and conductivity, allowing them to dissipate heat generated by high-capacity electrodes while maintaining structural integrity, thus enabling high battery capacity without sacrificing heat resistance.
Solution Approach 2:
The patent utilizes ceramic particles with controlled thermal expansion properties to accommodate thermal stress in high-capacity batteries. The ceramic-filled adhesive layer can expand and contract with temperature changes without degrading, maintaining adhesion between electrodes and separator even under high-temperature conditions associated with high-capacity operation.
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 enables the manufacturing of lithium batteries with enhanced adhesion characteristics, leading to improved lifetime and safety, particularly suitable for high-temperature and high-capacity applications, such as electric vehicles.
Implementation Method 1
an adhesive layer, wherein the adhesive layer of the separator contains ceramic particles and a binder at a mixing weight ratio of 4:6 to 6:4
Implementation Method 2
pressing the same under conditions of 10 to 20 kgf/cm2, 70 to 90° C. in temperature, and 1 to 5 minutes in time
Implementation Method 3
pressing the laminate under conditions of a pressure of 10 to 20 kgf/cm2 in pressure
Data Source
AI summary
Provided are a lithium battery and a manufacturing method therefor, the lithium battery comprising: a cathode; an anode; and a separator interposed between the cathode and the anode and including a porous substrate and an adhesive layer, wherein the adhesive layer of the separator contains ceramic particles and a binder at a mixing weight ratio of 4:6 to 6:4, the binder is a polyvinylidene fluoride-based compound, the binder includes a first binder and a second binder, and the adhesion ratio of the lithium battery, which is represented by equation 1 below, is 0.05 to 1.0.adhesion ratio={(dry adhesion−10)/(wet adhesion−350)} <Equation 1>In equation 1, dry adhesion and wet adhesion are as defined in the detailed description.