Battery Charge Control for Thermal Runaway Prevention
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Solution Overview
Problem
Lithium ion batteries, particularly those with NCA cathode materials, pose safety risks due to thermal runaway caused by the reaction of oxygen with organic electrolytes at elevated temperatures, leading to potential fires or explosions, necessitating a safe and reliable management system.
Innovation Solution
A method and device that determine operating parameters of the battery, compare them with reference values to identify predefined states, and discharge the battery until it reaches a safe state of charge below a critical threshold, preventing thermal runaway by ensuring the battery is not fully charged when high power is not required, thereby enhancing safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the battery is kept fully charged to maximize energy availability, then energy storage capacity is improved, but thermal runaway risk increases due to oxygen release from the cathode material
Solution Approach 1:
The control unit proactively discharges the battery to a safe state of charge before thermal runaway can occur, based on detected operating parameters. This preliminary action prevents the harmful effect by maintaining the battery in a safe charge state under critical operating conditions, rather than waiting for thermal runaway to begin.
2Reliability
If the battery is discharged to a safe state of charge to prevent thermal runaway, then safety is improved, but energy storage losses increase
Solution Approach 1:
The safe state of charge threshold is dynamically adjusted based on detected operating parameters such as temperature, load state, and ambient conditions. This allows the battery to maintain maximum energy availability when conditions are safe, while automatically transitioning to a conservative safe state only when critical conditions are detected, thereby minimizing unnecessary energy losses.
Solution Approach 2:
The control unit changes the operational parameter of state of charge based on detected conditions. Under normal conditions, the battery operates at high state of charge for maximum energy availability. When critical operating conditions are detected, the state of charge parameter is changed to a safe threshold, preventing thermal runaway while minimizing energy loss by only discharging when necessary.
3Reliability
If additional components are added to monitor and control battery state, then safety management capability is improved, but device complexity increases
Solution Approach 1:
The control unit performs multiple functions: it monitors operating parameters, determines state of charge, compares with safe thresholds, and controls battery discharge. By consolidating these safety management functions into a single multi-functional control unit rather than separate dedicated components for each function, the system achieves comprehensive safety management with minimal additional complexity.
Data Source
AI summary
The present invention relates to a method and a device for operating a battery, in particular a lithium ion battery, in a load. For this purpose, a determination (S10) is carried out of at least one operating parameter which describes the state of the battery or the load, a comparison (S20) of the at least one determined operating parameter with one reference value in each case in order to recognize whether a predefined state exists, and a discharge (S32) of the battery until the charge state of the battery lies below a specified critical charge state of the battery if it has been identified that the predefined state exists, wherein by discharging the battery, an energy store is charged by a discharge flow from the battery.