Parallel Battery Cell Venting Structure for Short-Circuit Isolation
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Solution Overview
Problem
In battery systems with multiple cells connected in parallel, internal short-circuits can lead to thermal runaway due to current flow between cells, causing excessive heat and potential external short-circuits, even with safety mechanisms like current interrupt devices (CID), as the insulating material between electrode terminals and sealing plates can melt, allowing contact and further short-circuits.
Innovation Solution
The battery system incorporates a discharge valve in each cell that releases gas when internal pressure rises, using this gas to push up the parallel connection bus bars and insulating plate, preventing contact between electrode terminals and sealing plates, and breaking the bus bars to cut off short-circuit currents, thereby preventing thermal runaway.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple battery cells are connected in parallel to increase output current and power, then the power source capacity is improved, but the risk of thermal runaway increases due to internal short-circuits causing current flow between cells
Solution Approach 1:
The patent converts the harmful effect of gas generation during internal short-circuit into a beneficial protective mechanism. When a battery cell experiences internal short-circuit, gas is generated and discharged through the discharge port, creating upward pressure that pushes the lid plate and insulating plate to separate the electrode terminals from the sealing plate, thereby automatically cutting off the short-circuit current path and preventing thermal runaway propagation to other parallel-connected cells
Solution Approach 2:
The patent introduces an insulating plate as an intermediary component between the sealing plate and the electrode terminals. This insulating plate acts as a mediator that can be displaced by gas pressure from the discharge port to physically separate the electrode terminals from the sealing plate, thereby interrupting the current path without requiring direct intervention in the electrical connection
2Reliability
If insulating material between electrode terminals and sealing plates is used to prevent short-circuits, then electrical insulation is improved, but the material can melt under high temperature causing external short-circuits
Solution Approach 1:
The insulating plate serves as a mechanical intermediary that physically separates the electrode terminals from the sealing plate. This mechanical separation mechanism bypasses the limitation of thermal stability of insulating materials, as the separation is achieved through gas pressure displacement rather than relying solely on the thermal resistance of the insulating material
Solution Approach 2:
The patent extracts the insulation function from the insulating material alone and transfers it to a mechanical separation mechanism. By removing the electrode terminals from contact with the sealing plate through gas pressure-driven displacement of the insulating plate, the system no longer depends on the thermal stability of the insulating material to prevent short-circuits
3Productivity
If parallel connection bus bars are used to connect battery cells, then current distribution is improved, but external short-circuits can occur through these bus bars when cells are internally short-circuited
Solution Approach 1:
The patent converts the harmful effect of gas generation during internal short-circuit into a beneficial protective mechanism. The gas pressure pushes the lid plate and insulating plate to separate the electrode terminals from the sealing plate, automatically cutting off the short-circuit current path through the parallel connection bus bars and preventing external short-circuits
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
This configuration effectively prevents external short-circuits and thermal runaway by using the discharged gas to maintain separation between electrode terminals and sealing plates, even when the insulating material melts, ensuring safety and reliability in parallel-connected battery systems.
Implementation Method 1
when a gas is discharged from the discharge port, external force acts upward on the lid plate due to the discharged gas
Data Source
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AI summary
In order to prevent occurrence of a short circuit through a sealing plate when a battery cell becomes abnormal, a battery system includes a battery block having a plurality of square battery cells (1) stacked in one direction, parallel connection bus bars (5X), insulating plate (7), and lid plate (8) fixed to insulating plate (7). Each square battery cell (1) has a discharge port provided with discharge valve (14) and a sealing plate provided with positive and negative electrode terminals via an insulating material. Parallel connection bus bars (5X) are connected to the electrode terminals to connect some or all of square battery cells (1) in parallel. Insulating plate (7) is disposed on the surfaces of sealing plates of the plurality of square battery cells (1) and includes passing portions having openings provided at positions corresponding to the discharge ports to pass the exhaust gas ejected from the discharge ports and pressing portions (22) disposed between parallel-connection bus bars (5X) and the sealing plates. Lid plate (8) faces discharge ports facing the openings of the passing portions.