Solid-State Lithium Battery Charging to Suppress Dendrite Short Circuits
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Solution Overview
Problem
Existing charging methods for all-solid-state lithium secondary batteries fail to sufficiently suppress short circuits caused by dendrite formation during the charging process.
Innovation Solution
A multi-stage charging method involving a first charging step at a controlled current density with pausing or discharging to maintain SOC below 4.5%, followed by a second charging step at a higher current density to increase the deposited Li layer thickness, effectively suppressing dendrite growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If constant current charging is used, then charging simplicity is maintained, but lithium plating occurs and battery life is reduced
Solution Approach 1:
The charging current is dynamically adjusted based on the battery's state of charge and temperature conditions. The controller transitions from constant current charging to constant voltage charging at different stages, and further adjusts current based on temperature thresholds, making the charging process adaptive rather than static.
Solution Approach 2:
The charging parameters (current and voltage) are changed based on temperature conditions and charging stage. The system modifies charging current according to temperature ranges (e.g., reducing current when temperature exceeds 45°C) and charging progress, preventing lithium plating while maintaining charging efficiency.
2Productivity
If charging current is increased to reduce charging time, then productivity improves, but temperature increases and safety risks arise
Solution Approach 1:
The charging process uses periodic temperature monitoring and adaptive current adjustment. The controller periodically checks temperature and adjusts charging current in stages, reducing current when temperature thresholds are exceeded, thereby managing heat generation while maintaining overall charging efficiency.
Solution Approach 2:
Charging current is dynamically adjusted based on real-time temperature feedback. The system increases current during safe temperature ranges to improve charging speed, and reduces current when temperature rises, creating a dynamic balance between charging productivity and thermal management.
3Reliability
If constant voltage charging is used, then overcharging is prevented, but charging time increases and productivity decreases
Solution Approach 1:
The charging process is segmented into multiple stages: initial constant current charging for rapid charge, followed by constant voltage charging for top-off, and further segmented by temperature conditions. This segmentation allows the system to maximize charging speed during safe phases while ensuring safety during critical phases.
Solution Approach 2:
The system performs preliminary constant current charging at higher rates before transitioning to constant voltage charging. This preliminary high-speed charging phase captures the majority of charging needs quickly, while the subsequent constant voltage phase completes the charge safely, optimizing overall charging time.
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 method significantly reduces the formation of fine dendrites, thereby enhancing the suppression of short circuits in the battery.
Implementation Method 1
If the battery is charged using a constant current charging method, a phenomenon known as lithium plating may occur, thereby reducing the life of the battery
Data Source
Figure 1
AI summary
[Abstract] To provide a means for more effectively suppressing a short circuits in a secondary battery. A method for charging a secondary battery including a positive electrode current collector, a positive electrode active material layer, a solid electrolyte layer, and a negative electrode current collector in this order and utilizing a deposition-dissolution reaction of metallic lithium as a reaction of a negative electrode, the method having a multi-stage charging step, and comprising at least: a first charging step in which the secondary battery is charged at a first current density I1 to deposit metallic lithium on a surface on the solid electrolyte layer side of the negative electrode current collector to form a deposited Li layer that is a part of a negative electrode active material layer and that comprises the metallic lithium; and a second charging step in which the secondary battery is charged at a second current density I2 greater than the first current density I1 after the first charging step to increase a thickness of the deposited Li layer, wherein the first charging step includes performing pausing at least once or discharging at least once, in which the secondary battery is charged at the first current density I1 so that an SOC does not exceed 4.5%.