Secondary Battery Safety Device with High Conductivity
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Solution Overview
Problem
Secondary batteries lack effective safety devices to rapidly sense internal temperature and respond to overheating or over-current conditions, posing risks to safety and stability.
Innovation Solution
A safety device with enhanced electric and thermal conductivity, positioned under a connection tab, is electrically connected to the electrode terminal via a nickel connection tab, incorporating a positive temperature coefficient (PTC) device and bi-metal components to disconnect leads upon temperature increase, ensuring rapid safety operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a safety device is added to sense temperature and prevent overheating, then safety is improved, but device complexity increases
Solution Approach 1:
The safety device utilizes the inherent PTC characteristics of the heating element itself to detect temperature and trigger protection, eliminating the need for separate temperature sensors and complex control circuits. The heating element automatically becomes the sensing element through its positive temperature coefficient property.
Solution Approach 2:
The heating element serves multiple functions: it heats the battery during charging while simultaneously acting as a temperature sensor through its PTC characteristics. This multi-functionality reduces the overall number of components needed in the safety system.
2Speed
If a PTC device with high thermal conductivity is used to rapidly sense temperature, then temperature sensing speed is improved, but thermal resistance increases
Solution Approach 1:
The patent optimizes the PTC device parameters including its resistance temperature coefficient, initial resistance, and thermal mass to achieve the right balance between thermal response speed and thermal resistance. By carefully selecting these parameters, the device responds quickly to temperature changes while maintaining acceptable thermal efficiency.
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 safety device effectively senses internal temperature and rapidly performs safety operations, improving the safety and stability of secondary batteries by increasing thermal resistance and sensitivity, thereby preventing overheating and over-current issues.
Implementation Method 1
a safety device, which has at least a predetermined area positioned under the connection tab, is electrically connected with the electrode terminal by the connection tab, and has at least one of electric conductivity and thermal conductivity higher than that of the connection tab
Implementation Method 2
incorporating a positive temperature coefficient (PTC) device and bi-metal components to disconnect leads upon temperature increase
Implementation Method 3
incorporating a positive temperature coefficient (PTC) device and bi-metal components to disconnect leads upon temperature increase
Data Source
AI summary
A secondary battery is disclosed. In one aspect, the secondary battery includes a case accommodating an electrode assembly, a cap plate sealing an opening of the case, an electrode terminal electrically connected to the electrode assembly and disposed over the cap, and an insulating member provided between the cap plate and the electrode terminal and configured to insulate the electrode terminal from the cap plate. The battery also includes a connection tab disposed over the electrode terminal, and a safety device having a portion positioned under the connection tab and electrically connected to the electrode terminal via the connection tab. The safety device has at least one of electric conductivity and thermal conductivity greater than that of the connection tab, and at least a part of the safety device is seated on the insulating member.