Silicon Anode Battery Management via Hysteresis Voltage Modeling
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Solution Overview
Problem
Current battery management systems struggle to accurately reflect the lithiation/delithiation properties and voltage relaxation behavior of silicon-containing lithium-ion battery cells, particularly due to significant volume expansion and crystal structure changes during charging/discharging, leading to inefficiencies in state of charge estimation and power prediction.
Innovation Solution
The development of battery management systems that utilize equations capturing the evolution of hysteresis voltage and amorphous/crystalline phase fractions of silicon-containing electrodes, enabling precise state of charge estimation and control by applying ordinary differential equations and adjusting delithiation boundary curves based on phase changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If pure silicon is used as negative electrode material to increase gravimetric capacity, then battery energy density is improved, but volume expansion during lithiation causes structural instability and reduced reliability
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the silicon anode has a different structure than traditional graphite. The silicon is confined in a specific geometry (spheroidal particles with diameter less than 1 micrometer) and is combined with a conductive carbon matrix, giving different properties to different regions: the silicon core provides high capacity while the carbon shell maintains structural stability and electrical conductivity.
Solution Approach 2:
The patent uses composite materials by combining silicon with conductive carbon to form a composite anode structure. This composite approach allows the silicon to provide high gravimetric capacity (3579 mAh/g) while the carbon matrix provides structural stability, electrical conductivity, and accommodates the volume expansion of silicon during lithiation, thus resolving the contradiction between high capacity and structural stability.
2Device complexity
If conventional battery management systems are used for silicon-containing batteries, then system simplicity is maintained, but state of charge estimation accuracy deteriorates due to hysteresis voltage and phase changes
Solution Approach 1:
The patent applies parameter changes by modifying the battery management system to account for the unique electrochemical parameters of silicon-containing anodes. The system incorporates equations that capture hysteresis voltage evolution and phase fraction changes specific to silicon lithiation/delithiation behavior. This allows accurate state of charge estimation by adapting the management parameters to match the actual physical and chemical behavior of the silicon-based battery.
3Speed
If fast charging is implemented to increase charging speed, then power delivery is improved, but voltage relaxation and phase changes cause estimation errors and reduce reliability
Solution Approach 1:
The patent implements feedback by using the battery management system to continuously monitor voltage, current, and temperature parameters during fast charging, and to update state of charge estimates based on equations that account for hysteresis voltage and phase fraction changes. The system uses this feedback to adjust charging parameters and provide accurate real-time state information, enabling reliable fast charging operation despite the dynamic voltage relaxation and phase transitions that occur in silicon-containing anodes.
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
These systems improve voltage prediction, state of charge estimation, and power prediction accuracy, allowing for enhanced fast charging algorithms and state of health estimation, while accounting for voltage relaxation and phase changes, thus optimizing the performance of silicon-containing lithium-ion batteries.
Implementation Method 1
voltage relaxation behavior of the battery cell based at least in part on lithiation or delithiation properties of the silicon-containing negative electrode
Implementation Method 2
voltage relaxation behavior of the battery cell based at least in part on lithiation or delithiation properties of the silicon-containing negative electrode
Implementation Method 3
applying an equation capturing the evolution of the hysteresis voltage of the battery cell
Implementation Method 4
applying an equation capturing the evolution of the hysteresis voltage of the battery cell... an equation accounting for amorphous and crystalline phase fractions
Data Source
AI summary
Battery management systems and methods for use with lithium-ion batteries that employ silicon-based negative electrodes. The battery management systems and methods consider the lithiation/delithiation properties of silicon-based anode materials by considering voltage relaxation behavior. The battery management systems and methods may also be applied to other materials that similarly display an apparent hysteresis in the lithiation/delithiation processes and/or form multiple phases with different electrochemical properties.