Si/Li Battery SOC Balancing Using Hysteresis-Aware Cell Models
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Solution Overview
Problem
Conventional battery management systems for Si/Li batteries face challenges in accurately estimating state-of-charge (SOC) due to the unique characteristics of silicon-dominant anodes, such as substantial voltage hysteresis and nonlinear changes in cell impedance, leading to inaccurate SOC balancing and reduced cycle life.
Innovation Solution
Implementing enhanced SOC models, including physical and machine-learning-based models, that account for the specific properties of Si/Li batteries, such as OCV hysteresis, mechanical strain, and SOH-dependent changes, to accurately calculate and balance the SOC of individual cells within a battery pack.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional SOC models are used for Si/Li batteries, then the system complexity is low, but the SOC estimation accuracy deteriorates due to voltage hysteresis and nonlinear impedance changes
Solution Approach 1:
The patent applies parameter changes by transitioning from conventional SOC estimation methods to enhanced models that incorporate voltage hysteresis parameters and nonlinear impedance characteristics specific to Si/Li batteries. This allows the system to adapt to the unique electrochemical behavior of silicon-dominant anodes, improving SOC accuracy without requiring fundamentally new system architecture.
Solution Approach 2:
The enhanced SOC models utilize feedback mechanisms by continuously monitoring voltage, current, and temperature parameters, then adjusting SOC estimates based on observed hysteresis loops and impedance variations. This closed-loop approach enables the system to compensate for Si/Li battery specificities dynamically, resolving the contradiction between model simplicity and estimation accuracy.
2Duration of action of stationary object
If SOC balancing is not accurately performed, then the battery management system operation is simple, but the cycle life deteriorates due to uneven cell states
Solution Approach 1:
The patent implements preliminary action by performing SOC balancing operations proactively based on predicted cell state divergences rather than waiting for actual imbalances to manifest. The enhanced models anticipate which cells are likely to deviate from uniform SOC and pre-adjust charging/discharging currents, extending cycle life while maintaining straightforward system operation.
Solution Approach 2:
The patent replaces complex mechanical balancing operations with intelligent control algorithms that use enhanced SOC models. Instead of physical interventions to equalize cell states, the system substitutes computational methods that calculate optimal current distribution across cells, achieving accurate SOC balancing through software-based control rather than mechanical means.
3Reliability
If conventional battery management approaches are used, then the implementation cost is low, but the battery lifetime is reduced due to inaccurate SOC management
Solution Approach 1:
The enhanced SOC models achieve universality by developing a comprehensive management approach that simultaneously addresses multiple Si/Li battery characteristics: voltage hysteresis, nonlinear impedance changes, and cell-to-cell variations. This multi-functional model serves as a universal solution for SOC estimation and balancing across different Si/Li battery configurations, improving reliability without proportionally increasing implementation complexity.
Solution Approach 2:
The patent introduces intermediary elements in the form of enhanced SOC models that mediate between raw battery parameters and control decisions. These models act as intermediaries that translate complex electrochemical behaviors into actionable SOC estimates and balancing commands, bridging the gap between conventional management approaches and the unique requirements of Si/Li batteries, thereby extending lifetime with manageable complexity.
Data Source
AI summary
Systems and methods are provided for state-of-charge balancing in battery management systems for Si/Li batteries. At least one state-of-charge (SOC) model may be configured, particularly to account for one or more unique characteristics associated with a cell type of one or more cells of the plurality of lithium-ion cells, and a state-of-charge (SOC) of a plurality of lithium-ion cells may be assessed. Based on the assessing of the state-of-charge (SOC), the plurality of lithium-ion cells may be controlled. The assessing may include calculating or estimating the state-of-charge (SOC) using the at least one state-of-charge (SOC) model. The controlling may be configured to equilibrate the state-of-charge (SOC) of the plurality of lithium-ion cells, or to modify a state-of-charge (SOC) of an individual lithium-ion cell or a group of lithium-ion cells, so that the plurality of lithium-ion cells as a whole has a balanced state-of-charge (SOC).