Secondary Battery Charging Method Using Staged Current Density
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Solution Overview
Problem
Lithium secondary batteries face challenges with battery short circuits due to high current charging and prolonged charging times when using low current charging, which necessitates a method to suppress short circuits while reducing charging time.
Innovation Solution
A charging method involving a two-stage current density approach, where the battery is initially charged at a low current density to form a roughness coating layer on the anode current collecting foil, followed by high current density charging to increase the layer thickness, with SOC calculation determining the switching point between the two stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If high current density charging is used, then charging time is reduced, but battery short circuit risk increases
Solution Approach 1:
The charging process is divided into multiple stages with different current densities. The first stage uses low current density to form a uniform lithium metal layer, and the second stage uses high current density to complete charging. This segmentation allows the system to achieve fast charging while preventing short circuits by controlling lithium deposition in a staged manner.
Solution Approach 2:
Before high current density charging, a preliminary low current density charging stage is performed to form a uniform lithium metal layer on the anode. This preliminary action creates a stable foundation that prevents short circuits during subsequent high current charging, as the uniform layer distributes current evenly and prevents dendrite formation.
2Reliability
If low current density charging is used, then short circuit risk is suppressed, but charging time is increased
Solution Approach 1:
The charging process is divided into multiple stages with different current densities. The first stage uses low current density to form a uniform lithium metal layer, and the second stage uses high current density to complete charging. This segmentation allows the system to achieve fast charging while preventing short circuits by controlling lithium deposition in a staged manner.
Solution Approach 2:
The current density parameter is dynamically changed during the charging process. It starts at a low value (0.1-0.5 mA/cm²) to form the lithium metal layer, then increases to a higher value (1-10 mA/cm²) for fast charging. This parameter change enables the system to optimize both safety and charging speed at different stages.
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 effectively suppresses battery short circuits and reduces charging time by ensuring uniform lithium metal precipitation and maintaining excellent interface contact between the solid electrolyte and anode current collecting foil, even during high current density charging.
Implementation Method 1
a roughness coating layer which is composed of precipitated lithium, is formed on an anode current collecting foil-side surface of a solid electrolyte layer
Implementation Method 2
a lithium secondary battery, a lithium metal precipitation-dissolution reaction as an anode reaction
Data Source
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AI summary
Provided is a method for charging a secondary battery configured to both suppress battery short circuits and to reduce battery charging time. The charging method is a multistep secondary battery charging method comprising first charging in which a secondary battery is charged at a first current density I1, and second charging in which the secondary battery is charged at a second current density 12 which is larger than the first current density I1, wherein, when a roughness height of an anode current collecting foil-side surface of a solid electrolyte layer is determined as Y (µm) and a thickness of a roughness coating layer is determined as X (µm), in the first charging, the secondary battery is charged at the first current density I1 until X/Y reaches 0.5 or more.