Solid-State Battery Charging via Cathode Potential Estimation
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Solution Overview
Problem
Existing battery systems face a decrease in performance due to changes in the crystal structure of the cathode active material, which is triggered by an increase in the cathode potential.
Innovation Solution
A battery system comprising a controller and a solid-state lithium secondary battery, where the controller estimates the end part cathode potential from the voltage relaxation amount and controls charging to ensure this potential remains equal to or less than the threshold at which crystal structure changes occur.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the cathode potential is increased to improve battery capacity, then the battery capacity is improved, but the crystal structure of the cathode active material changes causing performance degradation
Solution Approach 1:
The controller performs preliminary estimation of the end part cathode potential before completing the charging process. By calculating the voltage relaxation amount and estimating the potential in advance, the system can determine whether the cathode potential will exceed the crystal structure change threshold, and adjust charging parameters proactively to prevent performance degradation.
Solution Approach 2:
The controller continuously monitors the voltage relaxation amount during charging and uses this feedback to estimate the end part cathode potential. Based on this real-time estimation, the controller dynamically adjusts the charging current or voltage to ensure the cathode potential remains below the threshold that causes crystal structure changes, thus maintaining battery performance while maximizing capacity.
2Quantity of substance
If charging is continued to maximize battery capacity, then the battery capacity is improved, but lithium deposition occurs in the anode
Solution Approach 1:
The controller estimates the end part cathode potential before the charging is complete, allowing preliminary determination of whether lithium deposition risk exists. This early estimation enables the system to take preventive action by adjusting charging parameters before lithium deposition occurs.
Solution Approach 2:
The system uses real-time voltage relaxation measurements as feedback to continuously monitor the charging state. When the estimated potential indicates approaching dangerous levels that could cause lithium deposition, the controller adjusts charging parameters to prevent this harmful effect while still achieving maximum safe capacity.
3Ease of operation
If the charging control is simplified to improve ease of operation, then the ease of operation is improved, but the precision of potential estimation decreases
Solution Approach 1:
The controller automatically performs the complex calculations of voltage relaxation amount and end part cathode potential estimation without requiring user intervention. The system self-manages the precise monitoring and adjustment of charging parameters, maintaining high measurement precision while keeping the operation simple for the user.
Solution Approach 2:
The patent replaces complex manual monitoring and adjustment mechanisms with an automated electronic control system that uses computational algorithms to estimate potential and adjust charging parameters. This substitution of mechanical/manual processes with electronic computation maintains precision while simplifying operation.
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 effectively suppresses the decrease in battery performance by preventing changes in the crystal structure of the cathode active material, thereby maintaining optimal battery functionality.
Implementation Method 1
lithium transferred to the facing part of the anode from the cathode of the solid-state lithium secondary battery in a charged state
Implementation Method 2
the voltage relaxation amount ΔV2 is generated by diffusion of, into the non-facing part of the anode, lithium transferred to the facing part of the anode from the cathode
Data Source
AI summary
A battery system comprising a controller and a solid-state lithium secondary battery, wherein the controller estimates an end part cathode potential Ve2 from a voltage relaxation amount ΔV2; the end part cathode potential Ve2 is a local potential of an end part of the cathode; and the voltage relaxation amount ΔV2 is generated by diffusion of, into the non-facing part of the anode, lithium transferred to the facing part of the anode from the cathode of the solid-state lithium secondary battery in a charged state, and wherein the controller controls execution and inexecution of charging of the solid-state lithium secondary battery so that the end part cathode potential Ve2 is equal to or less than a potential Vlimit at which a change in crystal structure of the cathode active material occurs.