Battery Unit Shield Units Prevent Thermal Runaway Propagation
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Solution Overview
Problem
High-voltage lithium-ion battery cells in electric vehicles lack safety features to prevent thermal runaway propagation, which can lead to heat transmission and potential explosions in adjoining cells, especially as energy density increases, posing a risk to safety.
Innovation Solution
A battery unit design with adjacent cells featuring venting units and shield units with opening and closure elements, where the venting units open to release hot gas away from adjacent cells, and the shield units direct this gas through a duct for safe evacuation, preventing thermal runaway in connected cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If energy density of battery cells is increased to 200 Wh/kg or higher, then energy storage capacity is improved, but thermal stability deteriorates and risk of thermal runaway propagation increases
Solution Approach 1:
The battery unit is divided into multiple battery cells with individual venting units, allowing isolated containment of thermal events. Each cell can vent independently through its own venting unit, preventing thermal runaway from propagating to adjacent cells. The shield units further segment the space between cells to contain hot gas within specific zones.
Solution Approach 2:
Shield units are introduced as intermediary structures between adjacent battery cells. These shield units include shield walls with openings and closure elements that act as mediators to intercept and redirect hot gas flow from venting units, preventing direct thermal contact between adjacent cells while maintaining system compactness.
2Reliability
If venting units are added to battery cells, then thermal runaway is contained, but device complexity increases
Solution Approach 1:
The shield units serve multiple functions simultaneously: they act as thermal barriers between cells, provide pathways for hot gas evacuation through ducts, and support closure elements for dynamic sealing. This merging of functions reduces the need for separate safety components, thereby limiting complexity increase.
Solution Approach 2:
Closure elements are designed to dynamically transition between closed and open positions based on thermal conditions. When thermal runaway occurs, heat activates the closure elements to open, allowing controlled venting. This dynamic behavior provides adaptive safety without requiring complex control systems.
3Reliability
If shield units with closure elements are arranged between battery cells, then thermal runaway propagation is prevented, but manufacturing complexity increases
Solution Approach 1:
Shield units are pre-assembled with closure elements and duct structures before integration into the battery unit. The shield walls are pre-positioned between cell rows with openings aligned to venting unit locations. This preliminary assembly simplifies the final integration process and reduces manufacturing complexity.
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
Enhances safety by preventing thermal runaway in adjacent battery cells, ensuring no external fire or explosion for at least five minutes in case of an internal cell defect, thus safeguarding the battery unit and surrounding components.
Implementation Method 1
The closure element of the shield unit which is arranged closest to the battery cell can be transferred from its closed position into its open position by the action thereon of a thermal force generated from contact with hot gas
Implementation Method 2
a battery cell which experiences an internal short-circuit may then release heat exponentially (a thermal event), and transmit this heat to adjoining cells
Data Source
AI summary
A battery unit for a traction battery of a motor vehicle is provided. The battery unit includes at least two battery cells arranged adjacent to one another, which each include at least one venting unit for venting the cell housing thereof. The venting units are arranged on sides of the battery cells that are facing each other, and at least two shield units are arranged between the sides of the battery cells that face each other and at a distance from one another. Each shield unit includes a shield wall having at least one opening and at least one closure element. The opening of each shield wall is arranged aligned with the venting unit of the battery cell arranged closest to this shield wall in each case. The closure element, in a closing position, in which the closure element closes the opening, is arranged fully against the shield wall and in an open position, in which the closure element at least partially reveals the opening, is at least partially separated from the shield wall. The closure element can be transferred from the closing position into the open position by the action thereon of a force directed in the direction of the other shield unit.