Pre-Lithiated Negative Electrode With Concave Structure for Li-Ion Cells
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Solution Overview
Problem
Existing lithium secondary batteries suffer from initial irreversible capacity loss due to the formation of a solid electrolyte interface (SEI) on the negative electrode, which consumes lithium ions and reduces the battery's efficiency and cycle life, and existing pre-lithiation methods are costly or inefficient for mass production.
Innovation Solution
A negative electrode with a negative electrode active material layer containing diffused lithium metal ions and line-shaped concave portions, produced by applying a lithium metal pattern on a polymer release film, pressing, and pre-lithiating with a solution, enhancing electrolyte impregnability and initial reversibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pre-lithiation is performed to reduce initial irreversible capacity loss, then initial reversibility is improved, but production cost and process complexity increase
Solution Approach 1:
The patent applies preliminary action by forming a lithium metal pattern on a polymer release film before electrode assembly. This pre-positioned lithium pattern serves as a controlled lithium source that compensates for initial irreversible capacity loss during first charging, eliminating the need for complex post-assembly pre-lithiation processes while maintaining production simplicity
Solution Approach 2:
The polymer release film acts as an intermediary carrier that temporarily holds the lithium metal pattern in a controlled manner. This intermediary structure allows for easy handling and positioning of lithium metal during assembly, then enables controlled lithium release during battery operation, simplifying the overall production process while achieving pre-lithiation effects
2Quantity of substance
If lithium metal is used as negative electrode active material, then theoretical capacity is improved, but lithium atom growth damages separator and battery
Solution Approach 1:
The patent applies local quality by distributing lithium metal in discrete localized patterns rather than as a continuous layer. The lithium metal pattern consists of specific geometric shapes (circles, squares, triangles, or polygons) with controlled sizes and spacing, creating localized high-capacity regions that provide theoretical capacity benefits while limiting lithium atom migration and growth through spatial confinement
Solution Approach 2:
The lithium metal is segmented into multiple discrete patterns rather than used as a single continuous layer. This segmentation into separate geometric shapes reduces the continuity of lithium metal, preventing uncontrolled lithium atom growth while maintaining high theoretical capacity through the distributed patterned structure
3Reliability
If carbon-based material is used as negative electrode active material, then battery safety is improved, but theoretical capacity is reduced
Solution Approach 1:
The patent employs composite materials by combining carbon-based negative electrode active material with patterned lithium metal on a polymer release film. This composite structure integrates the safety advantages of carbon-based materials with the high capacity benefits of lithium metal, achieving both battery safety and high theoretical capacity through material composition rather than choosing one or the other
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 solution ensures improved initial reversibility and electrolyte impregnability, leading to enhanced electrochemical performance and capacity retention in lithium secondary batteries.
Implementation Method 1
lithium metal ions are diffused into the negative electrode active material layer
Implementation Method 2
lithium intercalation and deintercalation reactions into and from the negative electrode active material
Implementation Method 3
an electrolyte decomposition reaction on the surface of the negative electrode active material, and a solid electrolyte interface (SEI) is formed on the surface
Data Source
AI summary
A negative electrode for a lithium secondary battery, a method of producing the negative electrode, and a lithium secondary battery including the negative electrode. Specifically, the negative electrode can reduce the initial irreversibility of the negative electrode because lithium metal ions are diffused into the negative electrode active material layer by pre-lithiation, and the negative electrode active material layer into which the lithium metal ions are diffused includes a plurality of line-shaped concave portions, so that when the lithium secondary battery is produced later, the concave portion keeps an electrolyte solution therein well to improve the impregnability of the electrolyte solution, thereby ultimately improving the electrochemical performance of the lithium secondary battery.