Lithium Metal Electrode Activation to Protect Coated Anodes
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Solution Overview
Problem
Lithium metal secondary batteries with protective layers face degradation due to initial charging, leading to poor cycle characteristics as lithium metal is plated on the protective layer, causing side reactions and deformation.
Innovation Solution
A method where the lithium metal secondary battery is discharged first during the activation step to prevent lithium metal from being exposed to the electrolyte, using a protective layer composed of fluorinated organic copolymers or inorganic materials like lithium fluoride, which maintains the layer's integrity and prevents side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If initial charge is performed during activation step, then lithium metal is plated on the protective layer, but this causes side reactions with electrolyte and degrades cycle characteristics
Solution Approach 1:
The patent inverts the conventional activation sequence by performing discharge before charge. Instead of plating lithium metal onto the protective layer during initial charge, the discharge-then-charge sequence causes lithium metal to plate between the protective layer and lithium metal electrode, preventing direct contact between plated lithium and electrolyte, thereby eliminating side reactions and improving cycle characteristics
2Reliability
If lithium metal is plated on the protective layer during initial charge, then the protective layer is compromised, but this leads to deformation and loss of protective function
Solution Approach 1:
By reversing the activation sequence to discharge before charge, the patent ensures lithium metal plates in the correct location (between protective layer and electrode) rather than on the protective layer surface. This prevents mechanical deformation of the protective layer and maintains its integrity and protective function throughout battery operation
3Reliability
If conventional charge-first activation is used, then battery activation is simple, but over-voltage occurs during initial charge
Solution Approach 1:
The patent applies preliminary action by performing a discharge step before the initial charge during activation. This preliminary discharge prepares the battery system, enabling the subsequent charge to proceed without over-voltage issues. The additional discharge step is placed at the beginning of activation to prevent harmful effects during charging
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 alleviates over-voltage during the initial charge, minimizes protective layer deformation, and improves the battery's cycle characteristics by ensuring lithium metal is plated only on the surface where stripping occurs, thus enhancing the battery's performance.
Implementation Method 1
a protective layer formed thereon which prevents chemical reaction between the lithium metal electrode and the battery's electrolyte
Implementation Method 2
it is charged while lithium metal is plated on the negative electrode
Implementation Method 3
it is discharged while lithium metal is stripped
Data Source
Figure 1~2
Figure 3
AI summary
Disclosed is a method for manufacturing a lithium metal secondary battery including a lithium metal electrode as a negative electrode, wherein the lithium metal electrode has a protective layer formed thereon, and the lithium metal secondary battery is discharged before its initial charge during an activation step of the lithium metal secondary battery so that stripping occurs on the surface of the lithium metal electrode.