Full-Surface Electrode Insulation Film for Dendrite-Resistant Batteries
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Solution Overview
Problem
Lithium secondary batteries face safety issues due to short circuits, dendrite growth, and side reactions, which can lead to explosions and capacity loss, and existing solutions like insulation tapes and organic-inorganic mixed coating layers are insufficient in addressing these problems.
Innovation Solution
An electrode assembly with an organic-inorganic mixed insulation film containing inorganic particles and a binder polymer is formed on the entire surface of the electrodes, including tabs, to prevent short circuits and maintain lithium ion mobility, while also using thermally conductive inorganic particles to enhance safety and prevent thermal runaway.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an insulation tape is attached onto the electrode tab to prevent short circuit, then short circuit prevention is improved, but the solution is insufficient for ensuring battery safety against thermal runaway and dendrite penetration
Solution Approach 1:
The patent applies composite materials by forming an organic-inorganic mixed coating layer on the separator. This layer combines organic binder polymer (such as polyvinylidene fluoride-co-hexafluoropropylene) with inorganic particles (such as alumina, silica, or titania), creating a composite structure that provides both insulation properties and thermal stability. The inorganic particles prevent dendrite penetration while the organic matrix provides adhesion and flexibility, collectively preventing short circuits and thermal runaway.
Solution Approach 2:
The patent changes the physical and chemical parameters of the separator by coating it with an organic-inorganic mixed layer. The coating layer has different thermal properties compared to the base separator, with higher thermal stability and lower thermal shrinkage rate at elevated temperatures. This parameter change enables the separator to maintain its structural integrity and insulation properties under thermal stress, preventing thermal runaway.
2Temperature
If an organic-inorganic mixed coating layer is formed on the separator to prevent short circuit, then thermal stability is improved, but the coating layer may affect lithium ion mobility and battery performance
Solution Approach 1:
The patent employs porous materials by incorporating inorganic particles with controlled pore structures into the coating layer. These porous inorganic particles create channels and pathways that facilitate lithium ion transport while maintaining the thermal stability of the coating. The porosity allows electrolyte penetration and ion diffusion, ensuring that the coating layer does not impede lithium ion mobility despite providing thermal protection.
Solution Approach 2:
The patent applies local quality by creating a coating layer with spatially varying properties. The inorganic particles are distributed throughout the coating matrix, providing localized thermal stability and mechanical strength where needed, while the organic binder polymer provides continuity and ion conductivity. This local differentiation of properties allows the coating to simultaneously achieve thermal stability and maintain lithium ion mobility.
3Quantity of substance
If lithium metal is used as negative electrode active material to achieve high energy density, then energy density is improved, but dendrite growth occurs during charge-discharge cycles causing short circuit
Solution Approach 1:
The patent applies preliminary action by pre-coating the separator with an organic-inorganic mixed layer before battery assembly and operation. This pre-formed coating layer acts as a protective barrier that prevents dendrite growth and penetration from the outset, rather than relying on the separator's original structure alone. The coating is applied in advance to ensure uniform coverage and optimal protective properties before lithium metal dendrites can form and grow during cycling.
Solution Approach 2:
The patent uses the organic-inorganic mixed coating layer as an intermediary between the lithium metal negative electrode and the separator. This intermediary layer mediates the interaction by providing a physical barrier that blocks dendrite penetration while allowing lithium ion transport. The inorganic particles in the coating act as a mechanical barrier to dendrites, while the organic matrix maintains ion conductivity, effectively mediating between the high reactivity of lithium metal and the need for safe 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 effectively prevents short circuits, reduces gas generation, and maintains battery capacity and output performance, while providing improved safety against thermal runaway and nail penetration, outperforming traditional coating methods and insulation tapes.
Implementation Method 1
thermally conductive inorganic particles to enhance safety and prevent thermal runaway
Data Source
AI summary
An electrode assembly for a lithium secondary battery including an electrode, an insulation film, a separator and a counter electrode, wherein the insulation film is formed on an entire surface of one or both sides of the electrode, and the insulation film is an organic-inorganic mixed film including inorganic particles and a binder polymer. Also discussed is a manufacturing method thereof, and a lithium secondary battery including the same.