Negative Electrode Pre-Lithiation for Uniform SEI Film Formation
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Solution Overview
Problem
Existing methods for pre-lithiating negative electrodes in lithium secondary batteries face challenges in achieving uniform lithium ion diffusion and passivation film formation, leading to reduced battery capacity and cycle life.
Innovation Solution
A method involving a roll-to-roll process with a pre-lithiation bath divided into impregnation, pre-lithiation, and aging sections, using a lithium metal counter electrode for electrochemical charging to stabilize and uniformly diffuse lithium ions, forming a consistent passivation film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium metal is brought into contact with negative electrode structure for pre-lithiation, then lithium ions can be introduced to form passivation film, but uniform diffusion of lithium ions in negative electrode structure is difficult to achieve
Solution Approach 1:
A lithium salt-containing solution is introduced as an intermediary medium between the lithium metal counter electrode and the negative electrode structure. The solution facilitates uniform lithium ion diffusion to the negative electrode surface while preventing direct contact between lithium metal and the negative electrode, thereby achieving both passivation film formation and uniform pre-lithiation
Solution Approach 2:
The direct mechanical contact method (bringing lithium metal into contact with negative electrode) is replaced with an electrochemical system. A lithium metal counter electrode is used in an electrochemical cell configuration where lithium ions are transferred through a lithium salt-containing solution, enabling uniform distribution through ionic conduction rather than mechanical contact
2Manufacturing precision
If electrochemical charging method is used for pre-lithiation, then lithium ions can be uniformly diffused, but additional process steps and equipment are required
Solution Approach 1:
The pre-lithiation process is merged with the existing electrochemical cell assembly process. The lithium metal counter electrode and lithium salt-containing solution are integrated into the battery structure that will be used for actual operation, combining the pre-treatment step with the functional cell configuration rather than requiring separate equipment
Solution Approach 2:
The lithium metal counter electrode serves dual functions: it acts as a source of lithium ions during the pre-lithiation charging process, and it can function as a functional electrode in the final battery operation. The lithium salt-containing solution similarly serves both as the electrolyte medium for pre-lithiation and as the operating electrolyte in the battery
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 approach ensures uniform pre-lithiation and improved lifetime characteristics of the negative electrode, enhancing both processability and product quality consistency.
Implementation Method 1
allows pre-lithiation to be uniformly and stably performed by allowing lithium ions to be uniformly diffused in a negative electrode structure
Implementation Method 2
pre-lithiating the negative electrode structure having passed through the impregnation section while moving the same through the pre-lithiation section
Implementation Method 3
impregnating the negative electrode structure with the pre-lithiation solution while unwinding the negative electrode structure from the negative electrode roll
Data Source
AI summary
A method of producing a negative electrode, which includes: providing a negative electrode roll on which a negative electrode structure is wound, the negative electrode structure includes a negative electrode current collector and a negative electrode active material layer on at least one surface of the negative electrode current collector; providing a pre-lithiation bath containing a pre-lithiation solution, which is sequentially divided into an impregnation section, a pre-lithiation section, and an aging section; impregnating the negative electrode structure with the pre-lithiation solution while unwinding the negative electrode structure from the negative electrode roll and moving the same through the sections. The pre-lithiation is performed by disposing a lithium metal counter electrode, which is spaced apart from the negative electrode structure and impregnated with the pre-lithiation solution, in the pre-lithiation section and electrochemically charging the negative electrode structure.