Lithium-ion Cell Coil Sub-cell Fault Isolation
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Solution Overview
Problem
Lithium-ion accumulators face challenges in managing internal short-circuits, which can lead to uncontrolled discharging and increased thermal loading, limiting damage mitigation and reducing electrical energy density due to necessary robustness measures.
Innovation Solution
The lithium-ion accumulator is designed with sub-cells connected in parallel for normal operation, allowing for rapid electrical disconnection of defective sub-cells using a monitoring device, with insulating layers and specific winding configurations to prevent short-circuits and optimize heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical robustness is increased to prevent internal short-circuits, then reliability is improved, but material thickness increases and electrical energy density decreases
Solution Approach 1:
The accumulator is divided into multiple independently switchable sub-accumulators within a single cell coil. Each sub-accumulator can be selectively disconnected via individual switching elements, allowing fault isolation without requiring increased mechanical robustness across the entire structure. This segmentation enables reliability improvement through electrical isolation rather than mechanical thickening.
Solution Approach 2:
The invention extracts the protective function from mechanical structure and relocates it to electrical control systems. Instead of using thicker mechanical barriers to prevent short-circuits, the system uses monitoring devices and switching elements to detect and isolate faults electrically, thereby maintaining thin material thickness and high energy density.
2Reliability
If mechanical protective components are added to make lithium-ion accumulators more robust, then reliability is improved, but device complexity and costs increase
Solution Approach 1:
The invention replaces mechanical protective components with an electrical control system consisting of monitoring devices and switching elements. The system monitors the state of each sub-accumulator and uses electrical switching to isolate faults, substituting mechanical robustness measures with electronic control functions. This reduces mechanical complexity while maintaining or improving reliability.
3Temperature
If rapid discharge is performed to limit damage during internal short-circuit, then thermal loading is reduced, but uncontrolled discharging can occur without selective disconnection capability
Solution Approach 1:
The monitoring device continuously monitors the state of each sub-accumulator and prepares switching elements for rapid actuation. In the event of an internal short-circuit, the system can immediately disconnect the affected sub-accumulator before uncontrolled discharging occurs. This preliminary monitoring and preparation enable controlled rapid discharge that limits thermal loading while maintaining reliability.
Solution Approach 2:
The monitoring device provides continuous feedback on the state of each sub-accumulator, enabling real-time detection of internal short-circuits. This feedback mechanism allows the control system to initiate selective disconnection of faulty sub-accumulators, controlling the rapid discharge process to limit thermal loading while preventing uncontrolled discharging that would compromise reliability.
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 enables controlled discharge, minimizes heat release during faults, prevents chain reactions, and maintains high discharge current rates while reducing material thickness and costs, thus enhancing safety and efficiency.
Implementation Method 1
The intact sub-cell functions as a heat sink for the ohmic dissipated heat which is released during the rapid discharge
Implementation Method 2
a thermally conductive layer, by which heat can be carried away from the energy storage cell in the direction of the container wall
Data Source
AI summary
The invention relates to a cell coil (30, 40, 50, 60, 100, 200) for a lithium-ion battery, comprising at least two sub-cells (10, 32, 42, 44, 52, 54, 68, 70, 80, 82), which are wound in a space-saving manner and are thermally coupled to each other. According to the invention, the at least two sub-cells (10, 32, 42, 44, 52, 54, 68, 70, 80, 82) are electrically connected in parallel in normal operation, and, in the event of a fault, in particular in the event of an internal short circuit in at least one defective sub-cell (10, 32, 42, 44, 52, 54, 68, 70, 80, 82), at least one defective sub-cell (10, 32, 42, 44, 52, 54, 68, 70, 80, 82) can be electrically separated from the at least one intact sub-cell (10, 32, 42, 44, 52, 54, 68, 70, 80, 82). Because of the at least one defective sub-cell (10, 32, 42, 44, 52, 54, 68, 70, 80, 82) that can be immediately electrically separated from the intact sub-cells (10, 32, 42, 44, 52, 54, 68, 70, 80, 82) by means of an electronic monitoring device (36) in the “event of a fault”, a high level of robustness of the cell coil (30, 40, 50, 60, 100, 200) in respect of internal short circuits is achieved. Among other things, the intact sub-cells (10, 32, 42, 44, 52, 54, 68, 70, 80, 82) act, because of the thermal coupling between the sub-cells (10, 32, 42, 44, 52, 54, 68, 70, 80, 82), as a damage-reducing heat sink for the waste heat that is released during the fast discharge of the affected defective sub-cell (10, 32, 42, 44, 52, 54, 68, 70, 80, 82) generally occurring in the event of a short circuit.