Pattern-Coated Lithium Metal Pre-Lithiation for Negative Electrodes
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Solution Overview
Problem
The existing methods for pre-lithiation of negative electrodes in lithium secondary batteries are economically disadvantageous due to waste of lithium metal and increased electrolyte reduction, leading to low initial efficiency and capacity degradation.
Innovation Solution
A method involving pattern-coating of lithium metal foil on the negative electrode active material layer, followed by cutting and impregnation with an electrolyte, ensuring efficient use of lithium metal for pre-lithiation without waste, and minimizing spacing between electrodes during assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium metal is attached to the negative electrode through deposition or powder coating process, then pre-lithiation is achieved to reduce initial irreversibility, but lithium metal is wasted and electrolyte reduction is increased
Solution Approach 1:
The patent applies preliminary action by pre-coating lithium metal foil on the negative electrode active material layer before battery assembly. This allows the lithium to be positioned and fixed in advance, ensuring it will be effectively utilized during subsequent electrolyte injection and activation, thereby reducing waste while achieving pre-lithiation to improve initial reversibility.
Solution Approach 2:
The patent uses the negative electrode active material layer as an intermediary medium to hold and position the lithium metal foil. The lithium metal is coated on the active material layer rather than directly on the current collector, which serves as a mediator to secure the lithium in place and prevent waste during the battery manufacturing process.
2Reliability
If lithium metal is attached to the negative electrode, then pre-lithiation is achieved, but spacing phenomenon is generated in the positive electrode/separator/negative electrode
Solution Approach 1:
The patent applies preliminary action by pre-coating lithium metal foil on the negative electrode active material layer before battery assembly. This allows the lithium to be positioned and fixed in advance, ensuring it will be effectively utilized during subsequent electrolyte injection and activation, thereby reducing waste while achieving pre-lithiation to improve initial reversibility.
3Reliability
If lithium metal is used for pre-lithiation, then initial reversibility is improved, but electrolyte consumption is increased due to excessive lithium
Solution Approach 1:
The patent applies local quality by coating lithium metal foil only on specific portions of the negative electrode active material layer rather than uniformly across the entire electrode. This localized approach ensures that lithium is provided exactly where needed for pre-lithiation, improving initial reversibility while avoiding excessive lithium that would cause unnecessary electrolyte consumption and side reactions.
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 enhances the initial efficiency and capacity maintenance of lithium secondary batteries to 80% or more, while reducing the spacing phenomenon between the negative electrode and separator, thereby improving battery performance and cost-efficiency.
Implementation Method 1
lithium is ionized through the reaction between the lithium metal attached to the negative electrode layer and the electrolyte and then is intercalated into the negative electrode layer
Implementation Method 2
lithium ions intercalated to the positive electrode move to the negative electrode through the electrolyte
Implementation Method 3
During charge, the lithium ions intercalated to the positive electrode move to the negative electrode through the electrolyte. During discharge, the lithium ions move back to the positive electrode from the negative electrode
Implementation Method 4
lithium moving from the positive electrode to the negative electrode reacts with the electrolyte to form a kind of passivation film, solid electrolyte interface (SEI), on the surface of the negative electrode
Implementation Method 5
The SEI inhibits transport of electrons required for the reaction of the negative electrode with the electrolyte to prevent decomposition of the electrolyte
Data Source
AI summary
A method for manufacturing a lithium secondary battery, including the steps: (S1) forming a preliminary negative electrode by coating a negative electrode slurry including a negative electrode active material, conductive material, binder and a solvent onto at least one surface of a current collector, followed by drying and pressing the negative electrode slurry coated current collector, to form a negative electrode active material layer surface on the current collector; (S2) coating lithium metal foil onto the negative electrode active material layer surface of the preliminary negative electrode in the shape of a pattern in which pattern units are arranged; (S3) cutting the preliminary negative electrode on which the lithium metal foil is pattern-coated to obtain negative electrode units; (S4) impregnating the negative electrode units with an electrolyte to obtain a pre-lithiated negative electrode; and (S5) assembling the negative electrode obtained from step (S4) with a positive electrode and a separator.