Negative Electrode Pre-Lithiation Under High Pressure for Uniform SEI
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Solution Overview
Problem
Existing pre-lithiation methods for negative electrodes in secondary batteries suffer from non-uniformity due to solvent volatilization, leading to changes in the composition of the pre-lithiation solution, which affects the formation of the SEI film and reduces battery efficiency and cycle lifespan.
Innovation Solution
A high-pressure chamber surrounding the pre-lithiation reactor is used to maintain an internal pressure exceeding atmospheric pressure, preventing solvent volatilization and ensuring a constant solution composition, thereby promoting uniform pre-lithiation and improving battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional methods (elemental lithium or lithium foil) are used for pre-lithiation, then lithium supplement can be provided, but battery short circuit and safety issues occur due to volume expansion during alloying reactions
Solution Approach 1:
The patent changes the physical and chemical parameters of the lithium source from elemental lithium/foil to lithium-containing compounds (such as lithium phosphate, lithium sulfate, lithium oxalate). This parameter change allows lithium to be released through electrochemical decomposition at controlled potentials, avoiding the volume expansion issues of alloying reactions while still providing the necessary lithium supplement.
Solution Approach 2:
The patent uses lithium-containing compounds that decompose electrochemically to release lithium ions. These compounds act as disposable lithium sources that are consumed during the pre-lithiation process, eliminating the need for reversible alloying reactions and the associated safety issues. The decomposed compounds leave behind stable residues that do not cause short circuits.
2Quantity of substance
If LiCoO2 positive electrode material is used to supplement lithium, then lithium can be provided, but cobalt resource scarcity and high cost occur
Solution Approach 1:
The patent extracts the lithium component from lithium-containing compounds and uses it as the active pre-lithiation material, while leaving behind stable, non-toxic residues. This separates the useful lithium ions from the problematic cobalt-containing cathode materials, eliminating cobalt consumption while maintaining lithium supplement functionality.
Solution Approach 2:
The patent employs lithium-containing compounds that serve multiple functions: they provide lithium ions for pre-lithiation, decompose at controlled potentials to release lithium, and leave stable residues that do not interfere with battery operation. This multi-functionality replaces the need for cobalt-based materials while achieving the same lithium supplement goal.
3Quantity of substance
If lithium is supplemented by charging with a lithium salt solution, then lithium can be provided, but the process requires additional steps and time
Solution Approach 1:
The patent merges the pre-lithiation function with the existing electrode structure by incorporating lithium-containing compounds directly into the negative electrode or as a separate pre-treatment layer. This eliminates the need for separate charging steps with lithium salt solutions, as the lithium is released in-situ during battery assembly or initial charging, thereby improving manufacturing efficiency.
Solution Approach 2:
The patent performs pre-lithiation by incorporating lithium-containing compounds that will decompose and release lithium ions during the first charging cycle or during battery assembly. This preliminary action eliminates the need for subsequent separate lithium supplementation steps, streamlining the manufacturing process and improving productivity.
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-uniform pre-lithiation, enhancing the initial efficiency and cycle characteristics of the battery by maintaining a stable SEI film formation.
Implementation Method 1
it has been confirmed that a lithium-containing compound having a specific oxidation and reduction potential can be used for pre-lithiation of the negative electrode
Data Source
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AI summary
An apparatus for the pre-lithiation of a negative electrode comprises: a pre-lithiation reactor in which a pre-lithiation solution is accommodated; a high-pressure chamber surrounding the outside of the pre-lithiation reactor, and maintaining an internal air pressure exceeding atmospheric pressure; at least one lithium metal counter electrode disposed in the pre-lithiation solution so as to be facing and spaced a predetermined distance from a negative electrode introduced into the pre-lithiation solution; and a chargingand discharging unit electrically connected to the negative electrode and the lithium metal counter electrode.