Doped Lithium Strip Strength Control for Pre-lithiation
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Solution Overview
Problem
The existing pre-lithiation process for lithium-ion batteries faces challenges with edge cracking of lithium strips during rolling, leading to material wastage and increased production costs, due to mismatched tensile strength, width, and thickness, which affects the uniformity of pre-lithiation.
Innovation Solution
A metal lithium strip doped with at least two elements such as aluminum and sodium, with controlled strength, width, and thickness, ensuring σ2-(w/105h)² > 0, to prevent edge cracking and achieve uniform pre-lithiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium strip is used for pre-lithiation, then safety of pre-lithiation process is improved, but edge of lithium strip is prone to cracking during rolling process
Solution Approach 1:
The patent applies parameter changes by doping metal elements (such as magnesium, boron, aluminum, silicon, indium, zinc, silver, calcium, manganese, or sodium) into the lithium substrate to alter its mechanical properties. This doping process modifies the tensile strength and edge strength of the lithium strip, preventing cracking during rolling while maintaining the safety improvements of using lithium strip over lithium powder.
2Manufacturing precision
If lithium strip is rolled to reasonable thickness, then pre-lithiation effect is achieved, but edge cracking occurs causing material loss
Solution Approach 1:
The patent uses parameter changes by doping metal elements into the lithium substrate to enhance the edge strength and tensile strength of the lithium strip. This allows the strip to be rolled to the required thinness (e.g., 1-20 μm) without edge cracking, thereby achieving uniform thickness and preventing lithium metal loss during the rolling process.
3Strength
If strength of lithium strip is increased to prevent edge cracking, then rolling process is improved, but matching of strength, thickness and width becomes difficult
Solution Approach 1:
The patent applies parameter changes by doping metal elements into the lithium substrate, which simultaneously increases the tensile strength and modifies the mechanical properties to achieve proper matching among strength, thickness, and width parameters. This doping approach provides a systematic method to balance multiple parameters rather than adjusting them independently, reducing the complexity of achieving optimal matching.
Data Source
AI summary
The present embodiments provide a metal lithium strip, a prelithiated electrode plate, and a prelithiation process. The metal lithium strip comprises a lithium substrate and a metal element doped in the lithium substrate, the metal element comprises at least two of magnesium, boron, aluminum, silicon, indium, zinc, silver, calcium, manganese and sodium; and the metal lithium strip has a strength a, a width w, and a thickness h, satisfying: σ2-(w/105h)2>0. In the present application, the strength of the lithium strip is adjusted by the doping of the metal elements; meanwhile, the strength of the adjusted lithium strip is matched with its width and thickness ensuring that in the process of rolling the metal lithium strip to a reasonable thickness, the phenomenon of edge cracking of the lithium strip is avoided, lithium metal resources and production costs can be saved, a uniform pre-lithiation effect for electrode plate can also be achieved.