Battery Voltage Limiting for Cell Pressure Surge Control
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Solution Overview
Problem
Lithium metal batteries experience cell pressure surges due to volume changes during charge and discharge, leading to mechanical stresses, electrode damage, and reduced performance, which existing battery management systems fail to effectively mitigate.
Innovation Solution
A battery management system that actively limits the operational voltage of degraded cells using a 4D lookup table, based on cell pressure progression, cell voltage, temperature, and operational window, to prevent cell pressure surges and extend cycle life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the battery management system actively limits the operational voltage of degraded cells, then cell pressure surges are prevented and cycle life is extended, but device complexity increases due to the need for pressure sensing and control mechanisms
Solution Approach 1:
The system performs preliminary identification of degraded cells through pressure sensing before catastrophic failure occurs. By detecting pressure progression trends and identifying degraded cells in advance, the system can proactively adjust voltage limits to prevent pressure surges and extend cycle life, rather than reacting after damage has occurred.
Solution Approach 2:
The system implements continuous feedback monitoring of cell pressure to dynamically adjust operational voltage limits. Pressure sensors provide real-time feedback on cell state, enabling the control system to modify charging/discharging parameters for degraded cells, thereby preventing pressure surges while extending cycle life through adaptive control.
2Reliability
If pressure sensing and monitoring are implemented to identify degraded cells, then cell degradation can be detected early, but manufacturing cost increases due to additional sensors and processing requirements
Solution Approach 1:
The battery management system integrates multiple functions into existing components. The control unit that manages charging/discharging also performs degradation detection and voltage limit adjustment, eliminating the need for separate dedicated hardware modules. This multi-functionality approach maintains reliability while controlling manufacturing costs by utilizing existing system resources.
Solution Approach 2:
The system uses its own operational data (voltage, current, temperature) combined with pressure sensing to self-diagnose cell degradation states. By leveraging existing sensors and processing capabilities for degradation detection rather than requiring entirely new monitoring systems, the patent reduces manufacturing complexity and cost while maintaining reliable degradation identification.
Data Source
AI summary
Aspects of the disclosure include a battery management system that actively limits the operational voltage of a cell to avoid a cell pressure surge in response to an indicator of battery cell degradation. An exemplary battery management system can include a memory, computer readable instructions, and one or more processors that perform operations that include: measuring a first cell pressure of a cell of the battery pack at a reference voltage and measuring a second cell pressure of the cell of the battery pack at the reference voltage. A moving average of cell pressure progression is determined from the first cell pressure and the second cell pressure. Responsive to the moving average of cell pressure progression exceeding a cell pressure progression threshold, the cell of the battery pack is identified as a degraded cell and an estimate of remaining cycles for the degraded cell is determined.