Battery Safety Device Using Cell Swelling Detection
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Solution Overview
Problem
Conventional safety devices for preventing battery overcharging, whether passive or active, face challenges in accurately detecting cell swelling from trace amounts of gas, leading to potential thermal runaway and explosion, especially when sensors or switches malfunction, and they often require significant packaging space, limiting miniaturization and energy density.
Innovation Solution
A safety device with a switching unit that connects and disconnects electrical conduction between cells via a closed circuit, using a fuse as the electrical conduction control unit and a switching mechanism that responds to inflation pressure to accurately detect cell swelling and interrupt charging, allowing for compact design without the need for additional packaging space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional passive-type safety device is used, then the device structure is simple, but it cannot accurately detect cell swelling from trace amounts of gas and may fail to prevent thermal runaway
Solution Approach 1:
The patent introduces a switching unit as an intermediary component that detects cell swelling through a pressing force mechanism. This switching unit acts as a mediator between the cell and the safety circuit, converting the physical swelling into an electrical signal that triggers the safety response, thereby achieving accurate detection without complex sensing systems.
Solution Approach 2:
The safety device utilizes the cell's own swelling action to trigger the safety mechanism. The cell swelling itself generates the pressing force that activates the switching unit, eliminating the need for external sensors or power sources. The system serves itself by using the harmful swelling as the detection signal.
2Reliability
If an active-type safety structure with sensors and switches is used, then detection capability is improved, but the device cannot block current when the relay is short-circuited and requires significant packaging space
Solution Approach 1:
The patent extracts and eliminates the relay component from the safety system. By using a switching unit that directly interrupts current flow through the battery stack without requiring a relay, the design removes the vulnerability to relay short-circuiting while reducing the overall packaging space required for the safety device.
Solution Approach 2:
The switching unit is integrated directly into the battery stack structure, merging the safety function with the existing battery components. This integration eliminates the need for separate packaging space for safety devices while maintaining reliable operation under malfunction conditions.
3Use of energy by moving object
If medium or high capacity batteries are used to increase storage capacity, then electric energy storage is improved, but the batteries become large and heavy making installation difficult
Solution Approach 1:
The patent changes the physical state and density parameters of the battery by using a pouch structure instead of traditional rigid cases. This allows the battery to achieve high energy density with reduced weight and volume, enabling medium or high capacity storage without the penalty of excessive size and weight.
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 device effectively detects trace gas inflation to prevent overcharging by disconnecting the charging circuit, ensuring safety and increasing energy density per unit volume, enhancing the marketability of vehicles equipped with this technology.
Implementation Method 1
A passive-type safety device for preventing overcharging according to a conventional art uses an inflation pressure which is generated at the time of cell swelling.
Implementation Method 2
a safety circuit connected to two or more cells among the cells in the battery stack and provided with an electrical conduction control unit which is enabled or disabled to control electrical conduction
Data Source
AI summary
A safety device for preventing overcharging of a battery includes: a battery stack including a plurality of cells; a safety circuit connected to two or more cells and provided with an electrical conduction control unit that controls electrical conduction; and a closed circuit disposed between the cells connected to the safety circuit and provided with a switching unit which is switched on or off upon cell swelling, such that when cell swelling occurs, the switching unit is switched on by a pressing force, disabling the electrical conduction control unit of the safety circuit so electrical conduction between the cells is established via the switching unit, and when cell swelling occurs again, the switching unit is switched off, cutting off the electrical conduction between the cells.