Battery Cell End Cover Assembly With Grooved Pressure Relief Member
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Solution Overview
Problem
Lithium-ion batteries face safety hazards due to internal thermal runaway leading to increased pressure, which can cause fires or explosions, as existing pressure relief mechanisms in aluminum housings and end covers are prone to premature melting at high temperatures, compromising their effectiveness.
Innovation Solution
An end cover assembly with a pressure relief member having a lower hardness than the end cover, featuring an indentation groove that cracks to release pressure when internal pressure or temperature reaches a threshold, and a melting point higher than the pressure relief member, ensuring controlled pressure relief and preventing premature melting of the end cover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the end cover and pressure relief member are made of the same material (aluminum), then the manufacturing process is simplified, but the end cover melts prematurely at high temperatures during thermal runaway
Solution Approach 1:
The patent applies composite materials by using different materials for the end cover and pressure relief member. The end cover is made of aluminum alloy for ease of manufacturing, while the pressure relief member is made of a material with higher melting point and lower hardness to ensure high temperature resistance and controlled pressure relief. This resolves the contradiction by combining materials with complementary properties.
2Strength
If the pressure relief member has high hardness to withstand external force, then its anti-deformation capability is improved, but it becomes difficult to crack along the indentation groove for pressure relief
Solution Approach 1:
The patent changes the hardness parameter of the pressure relief member by selecting a material with lower hardness than the end cover. This allows the indentation groove to be formed more easily and for the member to crack along the groove at controlled pressure, while still providing sufficient anti-deformation capability through the groove geometry and material ductility.
3Ease of operation
If the indentation groove is made deep to facilitate cracking, then pressure relief is easier to achieve, but the anti-deformation capability is reduced due to thinner bottom wall
Solution Approach 1:
The patent optimizes the indentation groove parameters by controlling its depth and the bottom wall thickness. The groove is designed with sufficient depth to facilitate cracking at the required pressure, while maintaining adequate bottom wall thickness to preserve anti-deformation capability. This is achieved by adjusting geometric parameters within specific ranges.
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 reduces the risk of fire and explosion by allowing controlled pressure release and maintaining structural integrity at high temperatures, enhancing the safety and reliability of lithium-ion batteries.
Implementation Method 1
the pressure relief member is configured to crack along the indentation groove to release internal pressure of the battery cell when internal pressure or temperature of the battery cell reaches a threshold
Implementation Method 2
this is also convenient for the gas inside the battery cell to blow open the indentation groove of the pressure relief member
Implementation Method 3
the melting point of the pressure relief member is lower than the melting point of the end cover... the end cover can withstand higher temperature than the pressure relief member in the case of thermal runaway
Data Source
AI summary
An end cover assembly includes an end cover and a pressure relief member. The pressure relief member is provided in the end cover, and the pressure relief member is provided with an indentation groove. The pressure relief member is configured to crack along the indentation groove to release internal pressure of a battery cell when internal pressure or temperature of the battery cell reaches a threshold. Hardness of the pressure relief member is lower than hardness of the end cover.