Electrolyte-Mediated Electrode Pre-Lithiation for Uniform Doping
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Solution Overview
Problem
Existing pre-lithiation methods for negative electrodes in lithium secondary batteries result in non-homogeneous lithium doping due to direct contact with lithium metal, leading to initial irreversibility, SEI layer degradation, and electrolyte depletion, which cause capacity degradation and safety issues.
Innovation Solution
A method and apparatus for pre-lithiation that uses a pre-lithiation reaction system with two separate reaction systems: one with lithium metal, a separator, and an electrolyte, and another with the electrolyte and the electrode to be pre-lithiated, where the electrode is not in direct contact with lithium metal, allowing for homogeneous pre-lithiation and continuous processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium metal foil is in direct contact with negative electrode to carry out pre-lithiation, then pre-lithiation can be performed, but non-homogeneous pre-lithiation occurs depending on distance from electrode tab
Solution Approach 1:
The patent introduces an electrolyte solution as an intermediary medium to transfer lithium ions from the lithium foil to the negative electrode. Instead of direct contact, lithium ions dissolve in the electrolyte and diffuse to the electrode surface, ensuring uniform distribution. The electrolyte acts as a mediator that enables homogeneous lithium doping throughout the electrode area, eliminating the distance-dependent non-uniformity caused by direct contact methods.
Solution Approach 2:
The patent utilizes the fluid properties of the electrolyte solution to achieve uniform lithium distribution. The electrolyte flows or diffuses across the electrode surface, carrying lithium ions evenly to all regions. This hydraulic approach replaces the mechanical direct-contact method with a fluid-based transport mechanism, ensuring homogeneous pre-lithiation regardless of distance from the electrode tab.
2Quantity of substance
If direct contact pre-lithiation is used, then pre-lithiation can be achieved, but SEI layer destruction and electrolyte depletion occur
Solution Approach 1:
The electrolyte solution serves as a protective intermediary that enables gentle lithium ion transfer without direct mechanical contact between lithium foil and electrode. This indirect method prevents violent reactions that would destroy the SEI layer. The electrolyte mediates the lithium transfer process, allowing controlled ion diffusion that preserves the electrode structure and maintains long-term battery reliability.
Solution Approach 2:
The patent changes the physical state and transfer mechanism of lithium from solid-direct-contact to dissolved-ion-diffusion. By transforming lithium into ionic form in the electrolyte, the process becomes gentler and more controllable. This parameter change from solid-state direct contact to solution-state diffusion prevents SEI layer destruction and reduces electrolyte depletion, improving overall battery reliability.
3Quantity of substance
If lithium metal is used for pre-lithiation, then lithium doping can be performed, but non-homogeneous doping occurs depending on distance from counter electrode
Solution Approach 1:
The electrolyte solution acts as a universal intermediary that distributes lithium ions uniformly across the entire electrode surface. Instead of lithium ions being constrained by distance from the counter electrode, the electrolyte enables free diffusion of lithium ions to all regions of the electrode simultaneously, achieving homogeneous doping regardless of position.
Solution Approach 2:
The patent employs the electrolyte solution to achieve homogeneous lithium distribution throughout the electrode. The liquid medium ensures that lithium ions are evenly dispersed and deposited across the entire electrode surface, creating a uniform concentration profile. This homogeneity principle directly addresses the non-uniform doping problem caused by distance-dependent direct contact methods.
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 prevents non-homogeneous pre-lithiation, reduces the risk of lithium plating and side reactions, and enhances the safety and cycle characteristics of lithium secondary batteries by ensuring homogeneous doping and continuous electrolyte reuse.
Implementation Method 1
allowing lithium ion to be moved from the first reaction system to the second reaction system
Implementation Method 2
the electrolyte for pre-lithiation includes at least one of an organic material or an inorganic material capable of oxidation/reduction in the electrolyte
Data Source
AI summary
A method for pre-lithiation of an electrode, including a first step of providing a pre-lithiation reaction system which includes a first reaction system including lithium metal, a separator, an electrolyte for pre-lithiation and carbon felt, and a second reaction system including the electrolyte for pre-lithiation and an electrode to be pre-lithiated, wherein the lithium metal and the electrode to be pre-lithiated are not in direct contact with each other. The first reaction system and the second reaction system communicate with each other. The first step is followed by a second step of preparing an electrode including an electrode current collector, and an electrode active material layer formed on at least one surface of the electrode current collector; and a third step of allowing the electrode to pass through the second reaction system by a conveying roll to carry out pre-lithiation of the electrode.