Battery State Estimation Using Ion Concentration and Surface Pressure
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Solution Overview
Problem
Existing battery systems fail to accurately estimate the deterioration state and charge state of secondary batteries due to imbalances in lithium ion concentration, which are not solely between electrodes but also occur in planes and are influenced by electric current and surface pressure, leading to inaccurate assessments of battery health and performance.
Innovation Solution
A battery system that includes a controller estimating deterioration and charge states by calculating average ion concentration and ion concentration imbalances between electrodes, using electric current and surface pressure data, to improve accuracy and extend battery life by controlling output and input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If only ion concentration imbalance between electrodes is considered for battery state estimation, then the estimation method is simple, but the estimation accuracy is insufficient because it ignores ion concentration changes in the electrolytic solution plane and average ion concentration changes
Solution Approach 1:
The patent segments the ion concentration analysis into three distinct components: (1) ion concentration imbalance between electrodes, (2) ion concentration imbalance in the electrolytic solution plane, and (3) average ion concentration in the electrolytic solution. This segmentation allows each component to be calculated and considered separately, improving overall estimation accuracy while maintaining a structured approach to the complexity
Solution Approach 2:
The patent adds dimensional considerations to the estimation model by incorporating spatial variations in ion concentration. Specifically, it considers concentration variations not only between electrodes (one dimension) but also within the electrolytic solution plane (adding another dimension), and tracks changes in average concentration over time, thereby creating a multi-dimensional estimation framework
2Duration of action of stationary object
If the battery output is continuously controlled to prevent deterioration, then the battery lifespan is extended, but the productivity and power output are reduced
Solution Approach 1:
The patent implements dynamic control of battery output by continuously monitoring the estimated deterioration state and adjusting the allowable current accordingly. The control system dynamically determines the maximum current based on real-time battery state estimates, allowing the battery to operate at higher power levels when in good condition and reducing power levels only when deterioration indicators suggest risk, thereby optimizing both lifespan and productivity
Solution Approach 2:
The patent employs feedback control where the estimated deterioration state and ion concentration measurements continuously inform the output control decisions. The system uses the calculated ion concentration parameters to feedback-adjust the battery current, creating a closed-loop control system that adapts the power output based on actual battery condition rather than using fixed conservative limits
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
The system enhances the accuracy of battery state estimation by considering average ion concentration and ion concentration imbalances, preventing excessive usage or relaxation, thereby extending the battery's lifespan and improving input/output characteristics.
Implementation Method 1
When the secondary battery is discharged, the lithium ions in the electrolytic solution move from a negative electrode toward a positive electrode to produce the imbalance in the concentration of the lithium ions in the electrolytic solution
Implementation Method 2
The surface pressure of the secondary battery can be detected by a pressure sensor
Data Source
AI summary
A battery system includes a chargeable and dischargeable secondary battery and a controller that estimates the deterioration state or the charge state of the secondary battery. When estimating the deterioration state or the charge state, the controller uses an average ion concentration between a positive electrode and a negative electrode. The average ion concentration varies depending on an electric current flowing through the secondary battery. The average ion concentration between the electrodes can be calculated with a computing expression that includes a surface pressure of the secondary battery as a variable. The surface pressure of the secondary battery can be detected by a pressure sensor. The surface pressure of the secondary battery can also be estimated from an electric current flowing through the secondary battery.