Silane-Modified Separator Coating for Lithium Battery Safety
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Solution Overview
Problem
Non-aqueous lithium secondary batteries face deterioration and safety issues due to electrode contraction and expansion during charge and discharge cycles, leading to internal and external short circuits and rapid temperature increases, which can cause the separator to fuse and fail.
Innovation Solution
A method involving a coating layer formed on a separator using an inorganic compound and an organic/inorganic bindable silane compound with reactive functional groups, combined with a binder in the electrodes, to create a chemical bond through heat-treating, enhancing adherence and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separator is formed of a porous polyethylene film with shutdown characteristic, then safety is improved through pore closure at high temperature, but the separator may fuse and contract rapidly leading to short circuits when temperature increases
Solution Approach 1:
The patent applies composite materials by combining polyethylene separator with silane-modified inorganic compounds (such as alumina, silica, or boehmite) to create a composite coating layer. This composite structure provides both the shutdown function of polyethylene and the thermal stability of inorganic compounds, preventing separator fusion and contraction while maintaining safety.
Solution Approach 2:
The patent changes the thermal parameters of the separator by introducing inorganic compounds with high melting points and thermal stability into the polyethylene matrix. This parameter change elevates the overall heat resistance of the separator, allowing it to maintain structural integrity at temperatures where pure polyethylene would fuse and contract.
2Duration of action of moving object
If electrodes are repetitively contracted and expanded during charge and discharge cycles, then battery functionality is maintained, but electrodes react with separator or electrolyte causing deterioration and internal/external short circuits
Solution Approach 1:
The silane-modified inorganic compounds act as intermediary layers between the electrodes and the polyethylene separator. These intermediaries prevent direct contact and harmful reactions between electrode materials and the separator during electrode contraction and expansion, thereby maintaining battery stability and preventing short circuits while preserving cycle life.
Solution Approach 2:
The patent applies local quality by creating a specialized coating layer with specific chemical properties (silane modification) on the separator surface that directly contacts the electrodes. This localized modification provides enhanced chemical stability and reactivity control at the critical electrode-separator interface, preventing deterioration during cycling.
3Strength
If a coating layer with inorganic compound and silane compound is formed on separator, then adherence to electrodes and high-temperature stability are improved, but manufacturing process complexity increases
Solution Approach 1:
The silane compounds are pre-modified onto the inorganic compounds before applying them to the separator. This preliminary action ensures that the inorganic compounds are ready to chemically bond with the polyethylene separator upon contact, forming strong adhesion without requiring additional complex bonding steps during separator manufacturing.
Solution Approach 2:
The patent replaces mechanical adhesion methods with chemical bonding mechanisms. The silane-modified inorganic compounds form chemical bonds with the polyethylene separator through silane-polyethylene crosslinking reactions, providing superior adherence without requiring complex mechanical attachment systems or additional bonding equipment.
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 method improves the cycle-life characteristics, strength, and high-temperature stability of lithium secondary batteries by increasing adherence between the separator and electrodes, thereby reducing the risk of short circuits and enhancing safety.
Implementation Method 1
heat-treating the lithium secondary battery to react the first reactive functional group with the second reactive functional group to form a chemical bond
Data Source
AI summary
A method of preparing a lithium secondary battery is disclosed, the method including coating a coating layer-forming composition including an inorganic compound and an organic/inorganic bindable silane compound having a first reactive functional group on a substrate to form a separator including a coating layer; preparing an electrode including an active material and a binder having a second reactive functional group; stacking the electrode to contact the coating layer of the separator, and adding an electrolyte to the electrode and separator to prepare a lithium secondary battery; and heat-treating the lithium secondary battery to react the first reactive functional group with the second reactive functional group and form a chemical bond.