Negative Electrode Pre-Lithiation for Silicon Battery Stability
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Solution Overview
Problem
Lithium secondary batteries face issues with rapid charge/discharge characteristics and lifespan due to initial irreversible capacity and volume expansion of silicon-based materials, leading to structural damage and reduced battery capacity.
Innovation Solution
A method of preparing a negative electrode for lithium secondary batteries involves forming a mixture layer with a carbon or silicon-based material, disposing lithium metal powder in a patterned shape, pressing, and wetting with an electrolyte solution before assembly, which enhances pre-lithiation and reduces void formation, thereby improving structural stability and cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based material is used as negative electrode active material to achieve high capacity, then battery capacity is improved, but volume expansion rate increases by 300% or more leading to structural damage and reduced lifespan
Solution Approach 1:
The patent embeds lithium metal powder within the negative electrode mixture layer, creating a nested structure where the lithium source is integrated into the electrode architecture. This allows the lithium to be readily available for pre-lithiation while maintaining structural integrity during volume expansion cycles.
Solution Approach 2:
The patent performs pre-lithiation by incorporating lithium metal powder into the negative electrode before battery assembly and initial charging. This preliminary action compensates for the irreversible lithium consumption that occurs during SEI layer formation, thereby improving initial coulombic efficiency and extending battery lifespan without requiring post-assembly modifications.
2Reliability
If pre-lithiation is performed by putting negative electrode into lithium source-containing solution and applying current, then initial irreversibility is reduced, but a lot of by-products are generated and lithium oxide is produced only on the surface
Solution Approach 1:
The patent extracts the lithium source from an external solution and incorporates it directly into the negative electrode mixture layer as lithium metal powder. This eliminates the need for post-assembly electrolyte injection and current application, thereby avoiding by-product generation and ensuring uniform lithium distribution throughout the electrode volume rather than just on the surface.
3Duration of action of stationary object
If conventional pre-lithiation method is used to extend lifespan, then initial irreversibility is reduced, but lithium oxide is produced only on the surface limiting further irreversibility reduction
Solution Approach 1:
The lithium metal powder is nested within the negative electrode mixture layer, enabling uniform distribution throughout the electrode volume. This volumetric distribution ensures that lithium oxide is formed throughout the entire electrode rather than being confined to the surface, thereby maximizing the reduction of initial irreversibility and extending battery lifespan more effectively.
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 enhances the rapid charge/discharge characteristics and cycle performance of lithium secondary batteries by ensuring uniform lithium distribution and reducing initial irreversibility, leading to improved battery efficiency and lifespan.
Implementation Method 1
the present invention provides a method of preparing a negative electrode for a lithium secondary battery which includes a pre-lithiation process
Implementation Method 2
wetting the pressed negative electrode mixture layer with a first electrolyte solution
Data Source
AI summary
A method of preparing a negative electrode for a lithium secondary battery, which includes forming a negative electrode mixture layer including a negative electrode active material on a negative electrode current collector, disposing lithium metal powder on at least a part of the negative electrode mixture layer, pressing the negative electrode mixture layer on which the lithium metal powder is disposed, wetting the pressed negative electrode mixture layer with a first electrolyte solution, and drying the wet negative electrode mixture layer. A battery including the negative electrode of the present invention has enhanced rapid charge/discharge characteristics and enhanced lifespan characteristics.