Li-Ion Battery Cathode Prelithiation for Initial SEI Loss
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Solution Overview
Problem
Conventional lithium-ion batteries experience a significant decrease in capacity after initial charging due to lithium from the positive electrode active material being consumed to form a solid electrolyte interphase (SEI) in the negative electrode during charging.
Innovation Solution
A method for manufacturing lithium-ion batteries involving a positive electrode precursor layer with a lithium alloy having a lithium alloying potential of 0.5 V (vsLi/Li+) or higher, which is initially charged to prevent lithium from the positive electrode active material from being consumed in forming the SEI, thereby maintaining capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional positive electrode active material is used, then the battery can be manufactured with standard materials, but lithium is consumed to form SEI during initial charging causing significant capacity decrease
Solution Approach 1:
The patent applies preliminary action by incorporating a lithium alloy layer into the positive electrode precursor before battery assembly. This lithium alloy layer serves as a pre-prepared lithium source that will be activated during initial charging to form the SEI film on the negative electrode, preventing the need to consume lithium from the positive electrode active material later. The lithium alloy is strategically positioned and prepared in advance to perform the SEI-forming function before the main positive electrode material is depleted.
Solution Approach 2:
The lithium alloy layer acts as an intermediary substance between the positive electrode active material and the negative electrode. During initial charging, this intermediary lithium alloy layer provides lithium ions to form the SEI film on the negative electrode, shielding the main positive electrode active material from direct involvement in SEI formation. This mediator approach preserves the capacity of the primary positive electrode material while still achieving necessary SEI formation.
2Reliability
If lithium alloy is added to positive electrode precursor layer, then capacity loss is reduced, but device complexity increases
Solution Approach 1:
The patent merges the lithium alloy layer with the positive electrode precursor layer into a single integrated electrode structure. Rather than adding a separate, complex component, the lithium alloy is combined with the positive electrode materials (such as lithium NCM oxide) to form a unified precursor layer that can be manufactured using existing electrode fabrication processes. This merging approach maintains capacity retention benefits while minimizing increases in device complexity.
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
The method effectively reduces capacity loss after initial charging by ensuring lithium from the lithium alloy is used to form the SEI in the negative electrode, rather than being consumed from the positive electrode active material, thereby maintaining battery performance.
Implementation Method 1
a positive electrode precursor layer containing at least a lithium alloy with a lithium alloying potential of 0.5 V (vs Li/Li+) or higher
Implementation Method 2
lithium from the positive electrode active material being consumed to form a solid electrolyte interphase (SEI) in the negative electrode during charging
Data Source
AI summary
A method for manufacturing a lithium-ion battery according to the present disclosure includes: providing a positive electrode precursor layer containing at least a lithium (Li) alloy with a Li alloying potential of 0.5 V (vsLi/Li+) or higher and a positive electrode active material; obtaining a lithium-ion battery precursor including the positive electrode precursor layer, a separator layer, and a negative electrode active material layer in this order and impregnated with an electrolyte solution; and performing initial charging of the lithium-ion battery precursor to change the positive electrode precursor layer to a positive electrode active material layer.