Lithium Foil Production via Molten Deposition and Peeling
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Solution Overview
Problem
Current methods for producing thin lithium foils with thicknesses less than 10 µm are challenging, as they require separating agents that affect electrochemical performance and dendrite growth, and coating processes are costly and do not replicate the surface structure of rolled or cast films, while vapor deposition has low throughput and high costs for micrometer-scale deposition.
Innovation Solution
A method involving the application of molten lithium to a copper strip-shaped metal foil, using a lithium fluoride peeling tool to achieve the desired thickness, followed by the formation of a Solid Electrolyte Interphase (SEI) protective layer to prevent adhesion and enhance processing, including the use of a squeegee or roller tool and an immersion bath with ethylene carbonate and propylene carbonate electrolyte.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a separating agent such as silicone oil is used during processing of lithium, then adhesion of lithium to processing surfaces is reduced, but the separating agent influences electrochemical performance and dendrite growth during cycling
Solution Approach 1:
The invention extracts and removes the harmful separating agent from the system by using a release agent applied only during processing that can be completely removed before battery assembly, eliminating the compromise between ease of processing and electrochemical performance
Solution Approach 2:
The invention introduces a temporary intermediary substance (release agent) that facilitates processing but is designed to be completely removed afterward, serving as a mediator that enables easy manufacturing without leaving harmful residues that would affect electrochemical performance
2Manufacturing precision
If thin lithium foils with thickness less than 10 µm are produced by rolling processes, then thin foil production is achieved, but the process requires separating agents that affect electrochemical performance
Solution Approach 1:
The invention extracts the problematic separating agent requirement from the thin foil production process by using a removable release agent system, enabling precise thickness control down to less than 10 µm without compromising electrochemical performance
Solution Approach 2:
The invention changes the parameter of release agent type from permanent separating agents like silicone oil to removable release agents, enabling thin foil production with precise thickness control while eliminating the harmful effects on electrochemical performance
3Manufacturing precision
If coating processes are used to produce thin lithium layers, then lithium layers in the single-digit micrometer range can be produced, but the equipment complexity and costs are high
Solution Approach 1:
The invention replaces complex coating equipment with a simpler mechanical lamination process using a release agent, achieving single-digit micrometer thickness precision without the high equipment complexity and costs associated with vapor deposition or galvanic deposition systems
4Manufacturing precision
If vapor deposition is used to deposit lithium, then thin lithium layers can be produced, but the vapor deposition rates are low and throughput is low resulting in high costs
Solution Approach 1:
The invention replaces the slow vapor deposition process with a rapid mechanical lamination process using a release agent, achieving the same thin layer precision with dramatically higher throughput and lower costs
5Manufacturing precision
If coating processes are used to produce lithium layers, then lithium layers can be produced on metal foils, but the surface structure is not identical to that obtained by rolling or casting
Solution Approach 1:
The invention separates the thin lithium layer production from the substrate preparation by using a release agent, allowing the lithium to be applied as a thin conformal layer that replicates the underlying substrate's surface structure rather than creating a new coating surface
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
Enables the production of lithium layers with precise thickness and improved adhesion prevention, simplifying electrode film production and further processing, such as cutting, by forming a non-reactive surface that prevents sticking and enhances electrochemical performance.
Implementation Method 1
liquid lithium is first applied to at least one surface of the metal foil by melting. The lithium is in molten or molten form and has a temperature above the melting point of about 180.5 °C. Immediately after application, the liquid lithium forms a relatively thick layer on the surface of the metal foil.
Implementation Method 2
The remaining lithium then cools below the melting temperature and solidifies. The solidified lithium present in solid form then forms the lithium layer on the strip-shaped metal foil.
Implementation Method 3
an outer surface of the extraction tool, which comes into direct contact with the lithium when the lithium is extracted from the metal foil, is formed from lithium fluoride (LiF). It has been shown that molten liquid lithium does not adhere to lithium fluoride.
Implementation Method 4
when a battery is charged, a 'Solid Electrolyte Interphase' (SEI) is formed as reaction products from lithium and the components of the electrolyte, which consists of a mixture of the most diverse compounds.
Data Source
Figure 1~3
Figure 4
AI summary
The invention relates to a method for producing an electrode film (10) by applying a lithium layer (40) to a ribbon-shaped metal foil (20), wherein liquid lithium is applied to at least one surface (21) of the metal foil (20) by melting, and excess lithium is removed from the metal foil (20) by peeling it off with a peeling tool, wherein an outer surface of the peeling tool is formed from lithium fluoride. The invention also relates to an electrode for a battery cell, which comprises at least a portion of an electrode film (14) produced according to the invention.