Silicon Anode Battery SOC Estimation via Hysteresis Segmentation
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Solution Overview
Problem
Existing methods for determining the state of charge (SOC) of lithium-ion batteries with silicon-based anodes are inadequate due to hysteretic voltage-SOC dependence, which complicates accurate SOC estimation as the batteries age and deteriorate, affecting the relationship between terminal voltage and SOC.
Innovation Solution
The proposed solution involves circuitry that measures terminal voltage during charging and discharging modes to employ specific voltage-SOC relationships, adjusting for the hysteresis effect by using distinct relationships during charging and discharging phases, and adapting based on the state of health (SOH) to maintain accurate SOC estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single voltage-SOC relationship is used for battery SOC estimation, then the device complexity is reduced, but the measurement precision deteriorates due to hysteresis effects during charging and discharging
Solution Approach 1:
The patent divides the voltage-SOC relationship into separate charging and discharging curves, creating distinct models for each operational mode. This segmentation allows the system to account for hysteresis effects by selecting the appropriate curve based on whether the battery is charging or discharging, thereby improving SOC estimation accuracy without excessive complexity increase.
Solution Approach 2:
The patent implements a dynamic approach where the voltage-SOC relationship changes based on the battery's operational state (charging vs. discharging). The system dynamically selects between different voltage-SOC curves and adjusts parameters like hysteresis width and voltage offsets according to the current mode, enabling accurate SOC tracking throughout the battery lifecycle.
2Device complexity
If traditional SOC estimation methods are used, then the device complexity remains low, but the reliability deteriorates as the battery ages and SOH changes
Solution Approach 1:
The patent incorporates a feedback mechanism where the estimated SOH (State of Health) is used to adjust the voltage-SOC relationship parameters. As the battery ages and SOH changes, the system continuously updates the voltage offsets, hysteresis widths, and curve shapes based on measured capacity degradation, ensuring reliable SOC estimation throughout the battery's operational life.
Solution Approach 2:
The patent dynamically changes key parameters of the voltage-SOC relationship including voltage offsets, hysteresis widths, and curve shapes based on the battery's SOH. These parameter adjustments compensate for aging effects and capacity degradation, maintaining accurate SOC estimation even as the battery deteriorates over time.
3Ease of operation
If hysteresis effects are ignored in SOC estimation, then the ease of operation is improved, but the measurement precision deteriorates during charge-discharge cycles
Solution Approach 1:
The patent addresses hysteresis by segmenting the voltage-SOC relationship into distinct charging and discharging curves. This segmentation captures the hysteresis effect where the voltage-SOC relationship differs between charge and discharge modes, allowing the system to maintain ease of operation through automated curve selection while achieving high measurement precision.
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 approach enables precise estimation and display of SOC, accounting for the hysteresis and aging effects, providing a reliable 'fuel gauge' for lithium-ion batteries, ensuring accurate charge management and extending battery life.
Implementation Method 1
lithium-ion battery/cell having a silicon-based anode
Implementation Method 2
the relationship between the measured voltage and SOC changes (for example, the voltage curves of the battery/cell shift) as the battery/cell ages
Implementation Method 3
hysteretic voltage-SOC dependence, which complicates accurate SOC estimation as the batteries age and deteriorate
Data Source
AI summary
A system and technique for determining a state of charge (SOC) of a battery having at least two terminals and at least one silicon-based anode, or other anode materials exhibiting hysteretic voltage-SOC dependence such as tin-based anodes (whether partial or full dependence). The system and technique determines whether the battery is in a charge mode or a discharge mode of operation, measures a terminal voltage of the battery, and determines the SOC of the battery using (a) a first predetermined relationship between (i) the terminal voltage of the battery and (ii) the SOC of the battery when the battery is in a charge mode, and (b) a second predetermined relationship between (i) the terminal voltage of the battery and (ii) the SOC of the battery when the battery is in a discharge mode. In one embodiment, the terminal voltage is an equilibrium voltage of the battery.