Adaptive Lithium-Ion Battery Charging via Diffusion Control
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Solution Overview
Problem
Conventional lithium-ion battery charging techniques operate blindly, relying solely on cell voltage and failing to maintain optimal lithium surface concentration, leading to inefficient charging and potential saturation issues due to slow diffusion rates and manufacturing variability.
Innovation Solution
A system that adaptively controls the lithium surface concentration by determining the potential of the transport-limiting electrode relative to a reference, using this information to adjust charging voltage or current to maintain the lithium surface concentration within set limits, thereby optimizing charging efficiency and preventing saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional constant current or constant voltage charging is used, then charging simplicity is maintained, but lithium surface concentration cannot be controlled leading to saturation and reduced charging efficiency
Solution Approach 1:
The patent implements feedback control by continuously measuring the battery terminal voltage and using it to estimate the lithium surface concentration in real-time. The charging current is dynamically adjusted based on this estimated concentration to maintain it below saturation levels, thereby improving charging efficiency while preventing harmful saturation effects.
Solution Approach 2:
The system uses the battery's own voltage response during charging as a self-diagnostic signal to determine its internal lithium concentration state. By monitoring how the voltage changes in response to charging current, the system can autonomously adjust the charging rate without requiring external sensors or complex additional components.
2Loss of time
If high charging current is applied to reduce charging time, then charging speed increases, but lithium diffusion limitations cause surface saturation and potential battery damage
Solution Approach 1:
The patent applies dynamic charging control where the charging current is continuously varied based on the real-time estimated lithium surface concentration. The system transitions from static constant-current charging to a dynamic regime where the current adapts to the battery's instantaneous diffusion capacity, enabling faster charging without exceeding safety thresholds.
Solution Approach 2:
The system changes the charging parameter (current) as a function of the estimated lithium surface concentration. By continuously adjusting the charging current based on voltage measurements and diffusion models, the system optimizes the balance between charging speed and safety, allowing higher currents when diffusion capacity permits and reducing current when saturation risk increases.
3Reliability
If constant voltage charging is used to prevent saturation, then battery safety is maintained, but charging efficiency is reduced due to conservative current limits
Solution Approach 1:
The patent replaces the conservative mechanical constant-voltage charging approach with a model-based control system. Instead of simply holding voltage constant to prevent saturation, the system uses electrochemical diffusion models and real-time voltage measurements to predict and control lithium surface concentration, enabling more aggressive and efficient charging while maintaining safety.
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 allows for more efficient charging by utilizing available current while preventing lithium saturation, reducing charging time and improving battery performance across varying conditions.
Implementation Method 1
the net effect is dominated by slow diffusion processes for filling one electrode with lithium while removing it from the other
Implementation Method 2
the SEI acts as a barrier against further reactions with the electrolyte. Nevertheless, the SEI still allows transport of lithium ions, albeit with some degree of extra resistance
Data Source
AI summary
Some embodiments of the present invention provide a system that adaptively charges a battery, wherein the battery is a lithium-ion battery which includes a transport-limiting electrode governed by diffusion, an electrolyte separator and a non-transport-limiting electrode. During operation, the system determines a lithium surface concentration at an interface between the transport-limiting electrode and the electrolyte separator based on a diffusion time for lithium in the transport-limiting electrode. Next, the system calculates a charging current or a charging voltage for the battery based on the determined lithium surface concentration. Finally, the system applies the charging current or the charging voltage to the battery.