Pre-Lithiated Negative Electrode Polymer Layer Against Deformation
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Solution Overview
Problem
The deformation of pre-lithiated negative electrodes in secondary batteries leads to increased resistance and reduced energy density, lifespan, and durability due to stress from lithium insertion, causing defects in electrode assembly and side reactions.
Innovation Solution
A method involving the formation of a polymer layer on the current collector with a specific copolymer, including a first unit, a second unit, and a third unit, which reduces the brittleness and stress on the negative electrode active material layer, minimizing deformation and improving adhesion during the pre-lithiation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If pre-lithiation process is performed by bonding lithium metal to negative electrode active material layer, then irreversible capacity is reduced and energy density is improved, but strong stress is generated causing deformation of single-sided negative electrode
Solution Approach 1:
The patent divides the negative electrode into multiple layers: current collector, negative electrode active material layer, and polymer layer. This segmentation allows the polymer layer to independently bear the stress from lithium insertion, preventing deformation of the active material layer while maintaining the pre-lithiation effect.
Solution Approach 2:
The polymer layer acts as an intermediary between the current collector and the negative electrode active material layer. It mediates the stress generated during lithium insertion, absorbing the mechanical stress and preventing it from deforming the active material layer, thus enabling pre-lithiation without deformation.
2Device complexity
If single-sided negative electrode is used to reduce complexity, then manufacturing is simplified, but deformation prevents seamless bonding in electrode assembly
Solution Approach 1:
By segmenting the negative electrode structure and adding a polymer layer, the patent maintains the simplicity of single-sided electrodes while solving the bonding issue. The polymer layer prevents deformation, ensuring the electrode maintains its shape for seamless bonding.
3Quantity of substance
If deformation occurs in pre-lithiated negative electrode, then distance between negative electrode and positive electrode increases, but this increases resistance and causes side reactions
Solution Approach 1:
The polymer layer is applied beforehand to the current collector to cushion and absorb the stress that would otherwise cause deformation. This prior cushioning prevents the negative electrode from deforming during lithium insertion, maintaining proper electrode spacing and preventing increased resistance and side reactions.
Data Source
AI summary
Disclosed is a method for manufacturing of a negative electrode, a negative electrode, and a secondary battery, wherein the method includes forming a polymer layer on a rear surface of a current collector, forming a preliminary negative electrode active material layer on a front surface of the current collector, and forming a pre-lithiation layer including lithium on the preliminary negative electrode active material layer, wherein the polymer layer includes a copolymer having a first unit represented by Formula 1, and at least one of a second unit represented by Formula 2 or a third unit represented by Formula 3.