Integrated Electrode Assembly with Binder and Inorganic Coating Layers
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Solution Overview
Problem
Lithium ion batteries face safety issues due to internal short circuits caused by the melting or shrinking of polyolefin separators, leading to potential explosions, and existing inorganic coating layers on electrodes have low mechanical strength and adhesion, compromising battery safety and performance.
Innovation Solution
An integrated electrode assembly is developed with a positive electrode, a first binder polymer layer, an inorganic coating layer comprising inorganic particles with a dielectric constant of 5 or above, and a third binder polymer layer, sequentially stacked and combined to prevent internal short circuits and enhance adhesion, using a method that forms these layers on a release film and then laminates them with the electrode active material layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyolefin separator is used to prevent short circuit, then short circuit prevention is improved, but thermal stability deteriorates due to melting and shrinking at high temperatures
Solution Approach 1:
The patent uses a composite separator structure consisting of a polyolefin base layer combined with an inorganic coating layer containing particles such as alumina, silica, or boehmite. This composite structure maintains the short-circuit prevention function of the polyolefin while the inorganic coating layer provides thermal stability by preventing melting and shrinking at high temperatures, thus resolving the contradiction between short circuit prevention and thermal stability.
Solution Approach 2:
The inorganic coating layer is applied locally on the surface of the polyolefin separator rather than replacing the entire separator structure. This local modification approach preserves the bulk properties of the polyolefin for ion transport and mechanical flexibility while adding thermal stability only where needed on the separator surface, effectively resolving the thermal stability issue without compromising overall separator performance.
2Stability of the object's composition
If an inorganic coating layer is formed on the electrode to serve as separator, then thermal stability is improved, but mechanical strength deteriorates causing easy crack generation
Solution Approach 1:
The patent introduces a binder material as an intermediary substance that bonds the inorganic particles to each other and to the underlying electrode or separator substrate. This binder network provides mechanical strength and flexibility to the inorganic coating layer, preventing crack generation while maintaining the thermal stability provided by the inorganic particles, thus resolving the contradiction between thermal stability and mechanical strength.
Solution Approach 2:
The inorganic coating layer is formulated as a composite material system combining inorganic particles with an organic binder matrix. This composite structure allows the inorganic particles to provide thermal stability while the binder phase provides mechanical strength and flexibility, preventing the coating from cracking under stress and resolving the mechanical strength deterioration issue.
3Stability of the object's composition
If a composite separator with inorganic particle coating is used, then thermal stability is improved, but adhesion strength to electrodes deteriorates
Solution Approach 1:
The patent employs a surface treatment layer or binder material as an intermediary between the inorganic particle coating and the electrode surface. This intermediary layer improves wetting and bonding between the inorganic coating and the electrode, enhancing adhesion strength while preserving the thermal stability function of the inorganic particles, thus resolving the adhesion strength deterioration problem.
Solution Approach 2:
The patent optimizes parameters such as the chemical composition of the binder, surface treatment of inorganic particles, and coating process conditions to enhance the interfacial adhesion between the inorganic coating layer and the electrode. By adjusting these parameters, the adhesion strength is improved while maintaining the thermal stability provided by the inorganic particles, resolving the contradiction between thermal stability and adhesion strength.
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 prevents internal short circuits, improves adhesion between the inorganic coating layer and electrodes, and enhances the durability of the inorganic coating layer, resulting in improved cycle characteristics and safety of lithium secondary batteries.
Implementation Method 1
an inorganic coating layer comprising inorganic particles with a dielectric constant of 5 or above
Implementation Method 2
a first binder polymer layer, an inorganic coating layer comprising inorganic particles with a dielectric constant of 5 or above, and a third binder polymer layer, sequentially stacked and combined to prevent internal short circuits and enhance adhesion
Data Source
AI summary
The present disclosure relates to an integrated electrode assembly, wherein a positive electrode, a first binder polymer layer, an inorganic coating layer comprising a plurality of inorganic layers and a second binder polymer, a third binder polymer layer, and a negative electrode are sequentially stacked and combined, each configurative element forming the electrode assembly is stacked and combined with excellent adhesion, and the durability of the inorganic coating layer preventing the internal short circuit of the electrode is excellent, and thus a lithium secondary battery using the integrated electrode assembly according to the present disclosure may have excellent cycle characteristics.