Lithium Metal Layer Negative Electrode for Battery Pre-lithiation
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Solution Overview
Problem
Existing lithium secondary batteries face significant irreversible capacity loss due to the formation of the Solid Electrolyte Interface (SEI) during the initial charge, which limits their performance and cycle life, and conventional pre-lithiation methods are inefficient and costly for mass production.
Innovation Solution
A negative electrode for lithium secondary batteries is designed with a lithium metal layer and an adhesive layer containing lithium and metal oxide in a specific weight ratio, which allows for effective pre-lithiation without the need for separate lithium deposition or wetting processes, enhancing the attachment and diffusion of lithium ions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional pre-lithiation methods (depositing lithium or directly contacting with lithium) are used, then initial irreversible capacity loss is reduced, but manufacturing complexity and cost increase due to additional deposition apparatus and processing time
Solution Approach 1:
The invention combines the pre-lithiation function with the negative electrode active material layer itself by incorporating lithium-containing compounds (such as lithium oxide, lithium hydroxide, lithium carbonate, or lithium carboxylate) directly into the electrode structure. This integration eliminates the need for separate lithium deposition apparatus and additional processing steps, thereby reducing manufacturing complexity while maintaining the benefit of reduced irreversible capacity loss.
Solution Approach 2:
The negative electrode active material layer is designed to automatically provide lithium ions during initial charge through the incorporated lithium-containing compounds. This self-service mechanism eliminates the need for external lithium sources or complex deposition processes, simplifying the manufacturing system while effectively addressing the irreversible capacity loss issue.
2Loss of energy
If conventional pre-lithiation methods (depositing lithium or directly contacting with lithium) are used, then initial irreversible capacity loss is reduced, but production time increases due to additional processing steps
Solution Approach 1:
The pre-lithiation functionality is merged into the standard negative electrode manufacturing process by incorporating lithium-containing compounds during the slurry preparation and coating stages. This integration allows pre-lithiation to occur simultaneously with normal electrode production without requiring separate processing steps, thereby maintaining high production efficiency while reducing irreversible capacity loss.
Solution Approach 2:
Lithium-containing compounds are incorporated into the negative electrode active material layer during the standard manufacturing process, performing the pre-lithiation action in advance during normal production. This eliminates the need for separate pre-lithiation processing steps, maintaining mass production efficiency while achieving the desired reduction in irreversible capacity loss.
3Reliability
If carbon-based materials are used as negative electrode active material, then battery safety is improved by preventing separator damage, but capacity is reduced due to theoretical capacity limitation of about 400 mAh/g
Solution Approach 1:
The invention uses composite negative electrode active material layers that combine carbon-based materials (graphite, activated carbon) with lithium-containing compounds (lithium oxide, lithium hydroxide, lithium carbonate, or lithium carboxylate). This composite structure maintains the safety benefits of carbon-based materials while the lithium-containing compounds provide additional lithium ions to achieve higher practical capacity exceeding the theoretical 400 mAh/g limitation of pure carbon materials.
Solution Approach 2:
The invention changes the chemical composition parameters of the negative electrode by incorporating lithium-containing compounds with specific lithium content (0.1-5.0 wt% based on total negative electrode active material weight). This parameter modification allows the electrode to provide additional lithium ions during initial charge, increasing practical capacity while maintaining the safety characteristics of carbon-based materials.
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 configuration reduces irreversible capacity loss, improves initial efficiency, and extends the cycle life of lithium secondary batteries by ensuring complete consumption of the lithium metal during the initial activation charge, thereby enhancing the battery's capacity characteristics.
Implementation Method 1
a process of intercalating and deintercalating lithium ions from the positive electrode active material of the positive electrode into and out of the negative electrode active material of the negative electrode is repeated
Implementation Method 2
an electrolyte decomposition reaction on a surface of the negative electrode active material, and an SEI (Solid Electrolyte Interface) is formed on the surface of the negative electrode active material by an electrochemical reaction due to the electrolyte decomposition
Implementation Method 3
when a surface of the negative electrode active material is subjected to oxidation in a state in which the adhesive layer and the lithium metal layer are disposed on the negative electrode active material, lithium ions are generated in an amount corresponding to the oxidation
Data Source
AI summary
The present invention relates to a negative electrode for a secondary battery which comprises a negative electrode collector, a negative electrode active material layer formed on the negative electrode collector, and a lithium metal layer, wherein an adhesive layer is disposed between the negative electrode active material layer and the lithium metal layer, and the lithium metal layer comprises lithium and metal oxide in a weight ratio of 50:50 to 99:1.