Solid-State Battery Charging with Staged Current to Suppress Dendrites
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Solution Overview
Problem
Existing charging methods for secondary batteries, such as those described in JP 2020-009724 A, sometimes fail to sufficiently suppress short circuits in all-solid-state lithium secondary batteries.
Innovation Solution
The method involves a multi-stage charging process with a first charging step where the battery is charged at a first current density I1, pausing or discharging at least once, and ensuring the State of Charge (SOC) does not exceed 4.5%, followed by a second charging step at a higher current density I2 to increase the thickness of the deposited Li layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If charging is performed at high current density to reduce charging time, then productivity is improved, but dendrite formation increases causing short circuits
Solution Approach 1:
The charging process is divided into multiple stages with different current densities. The first stage uses a lower current density (0.05-0.20 mA/cm²) to form an initial Li layer, and the second stage uses a higher current density (0.20-1.00 mA/cm²) to increase Li layer thickness. This segmentation allows the system to achieve both safe initial formation and high-speed subsequent charging, resolving the contradiction between charging speed and short circuit suppression.
Solution Approach 2:
Before performing high-current charging, the method first performs a preliminary charging stage at lower current density to form an initial Li layer on the negative electrode. This preliminary action creates a protective foundation that prevents dendrite formation during subsequent high-current charging, enabling both high productivity and reliability.
2Productivity
If charging continues without interruption to reduce time, then productivity is improved, but dendrite formation increases causing short circuits
Solution Approach 1:
The charging process incorporates periodic pauses between the first and second charging stages. This periodic interruption allows the Li layer to form uniformly and prevents continuous high-current stress that would cause dendrite formation. The method thus achieves both reduced charging time and improved short circuit suppression through controlled periodic action.
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 effectively reduces the formation of fine dendrites and significantly suppresses short circuits in the secondary battery compared to conventional techniques.
Implementation Method 1
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
Implementation Method 2
The solid electrolyte is a material mainly made of an ion conductor capable of ion conduction in a solid
Data Source
AI summary
A method for charging a secondary battery utilizing a deposition-dissolution reaction of metallic lithium as a reaction of a negative electrode has a multi-stage charging step. The method comprises at least: a first charging step in which the secondary battery is charged at a first current density 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; and a second charging step in which the secondary battery is charged at a second current density greater than the first current density 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 so that an SOC does not exceed 4.5%.