Battery Cap Assembly Insulating Coating for Reconnection Prevention
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Solution Overview
Problem
Existing battery cap assemblies face safety issues due to reconnection of the pressure relief piece with the connector during external short circuits, particularly when the internal insulating washer thermally melts or abnormally deforms, leading to potential reoccurrence of short circuits and increased risk, and the current materials like PFA are costly.
Innovation Solution
Applying an insulating coating comprising inorganic particles, a binding agent, and a solvent to the peripheral and transition parts of the connector, which prevents reconnection by maintaining insulation even after thermal melting or abnormal deformation, and includes a method for applying a single-sided coating using spraying or printing, controlling the coating thickness to ensure effective insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the internal insulating washer is made of PFA to increase thermal stability, then the resistance to thermal melting is improved, but the manufacturing cost increases
Solution Approach 1:
The patent uses a composite structure combining PFA insulating washer with an inorganic insulating coating (such as glass enamel or ceramic coating) on the connector surface. This composite approach leverages the high thermal stability of PFA while adding the superior heat resistance and electrical insulation properties of inorganic coatings, achieving enhanced reliability without relying solely on expensive PFA material throughout the entire assembly
Solution Approach 2:
The inorganic insulating coating is applied locally to the connector surface at the transition part and peripheral part where insulation is most critical. This localized treatment provides enhanced thermal and electrical insulation precisely where needed during short circuit conditions, rather than requiring expensive PFA material throughout the entire connector structure
2Reliability
If the internal insulating washer is thermally melted during external short circuit, then the circuit break function is achieved, but the reconnection risk increases due to loss of insulation
Solution Approach 1:
The inorganic insulating coating is applied beforehand to the connector surface at the transition part and peripheral part to create a pre-existing protective barrier. This coating remains stable even when the PFA insulating washer melts during external short circuit, providing a backup insulation layer that prevents reconnection and maintains the circuit break function
Solution Approach 2:
The inorganic insulating coating acts as an intermediary protective layer between the connector metal and the pressure relief piece. When the PFA insulating washer melts, this coating serves as a mediator that maintains electrical insulation and prevents direct contact between conductive surfaces, thereby eliminating reconnection risk
3Ease of operation
If the insulating washer cannot cover the transition part due to installation limitations, then the installation ease is improved, but the insulation coverage is insufficient leading to short circuit risk
Solution Approach 1:
The solution extends insulation protection to a new dimension by applying an inorganic insulating coating directly onto the connector surface at the transition part and peripheral part. This coating-based approach complements the washer-based insulation, providing coverage in areas that are difficult to reach with traditional insulating washers due to installation constraints
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 insulating coating effectively prevents reconnection between the connector and pressure relief piece, enhancing safety during external short circuits while being cost-effective, and counteracting insulation degradation and wear-related issues, thus improving the overall safety and reducing the risk of short circuit recurrence.
Implementation Method 1
the internal insulating washer plays a key insulating role when the pressure relief piece turns over. However, prolonged thermal accumulation at large short-circuit currents can cause thermal melting of the internal insulating washer
Implementation Method 2
the overall thermoforming temperature of PFA is high, which increases the costs of the cell to some extent
Data Source
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AI summary
The present invention relates to a cap assembly for a battery, comprising: a connector, the connector comprising a central part, a peripheral part, and a transition part between the former two parts, wherein a current interrupt device is disposed on the central part; a pressure relief piece, the pressure relief piece being located outside a cell of the battery with respect to the connector and electrically connected to the connector via the current interrupt device, and being able to turn over when the internal pressure of the cell exceeds the overturning gas pressure of the pressure relief piece so as to disconnect the current interrupt device, cutting off the electrical connection between the pressure relief piece and the connector; and an internal insulating washer, the internal insulating washer being disposed on the peripheral part of the connector, wherein an insulating coating is applied to the peripheral part and transition part of the connector on one side facing the pressure relief piece. The insulating coating can prevent reconnection of the connector to the pressure relief piece in the case of an external short circuit and improve the short circuit safety of the battery. The present application further relates to a method for making a connector for the cap assembly and to a battery comprising the cap assembly.