Battery Electrode Insulating Layer Adhesion at High Temperature
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Solution Overview
Problem
Conventional electrodes in secondary batteries face the risk of short circuits due to the separation of insulating layers from active material layers at high temperatures, leading to exposure and potential short circuits between positive and negative electrodes.
Innovation Solution
The electrode design includes a current collector with an active material layer and an insulating layer, where the peeling strength between the current collector and the active material layer is maintained at 10 mN/mm or more during a 90° peeling test at a rate of 100 mm/min, ensuring the insulating layer remains intact even at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyolefin system separator is used to prevent short circuits, then short circuit prevention is improved, but at high temperatures the separator melts causing large area short circuits
Solution Approach 1:
The patent extracts the insulating function from the separator and transfers it to the insulating layer formed on the active material layer. This allows the separator to be replaced with materials having higher thermal stability (melting points above 200°C) while maintaining short circuit prevention through the insulating layer with peeling strength of 10 mN/mm or more.
Solution Approach 2:
The patent uses composite materials for the insulating layer comprising inorganic particles (alumina, silica, titania) dispersed in a binder resin matrix. This composite structure provides both the necessary electrical insulation and thermal stability, with the inorganic particles maintaining structural integrity at high temperatures while the binder provides adhesion.
2Temperature
If an insulating layer is formed on the active material layer to prevent short circuits at high temperature, then thermal safety is improved, but the insulating layer may peel off exposing the active material layer
Solution Approach 1:
The patent specifies precise parameter ranges for the insulating layer: thickness of 1-30 μm, inorganic particle content of 70-99 mass%, binder resin content of 1-30 mass%, and peeling strength of 10 mN/mm or more. These parameter controls ensure both thermal stability and adequate adhesion, preventing peeling while maintaining insulating function.
Solution Approach 2:
The insulating layer uses a composite structure with inorganic particles (alumina, silica, titania) dispersed in a binder resin. The inorganic particles provide thermal stability and structural integrity at high temperatures, while the binder resin ensures adequate adhesion to the active material layer, achieving both thermal safety and layer stability.
3Ease of manufacture
If the insulating layer is made thin to maintain flexibility, then ease of manufacture is improved, but short circuit prevention capability deteriorates
Solution Approach 1:
The patent optimizes the insulating layer thickness to 1-30 μm, with preferred ranges of 3-20 μm or 5-15 μm. This thin thickness ensures ease of manufacture and flexibility while the high inorganic particle content (70-99 mass%) and controlled peeling strength (≥10 mN/mm) maintain adequate insulation performance and prevent short circuits.
Data Source
AI summary
Provided is an electrode for a battery which effectively suppress a short circuit between a positive electrode and a negative electrode at high temperature of the battery.The electrode includes a current collector 110, an active material layer 111 formed on at least one side of the current collector 110 and an insulating layer 112 formed on the surface of the active material layer 111. The electrode was formed so that peeling occurs between the current collector 110 and the active material layer 111 and the peeling strength was 10 mN/mm or more when a 90° peeling test was performed at a peeling rate of 100/min.