Current Collector Surface Structures for SEI Control
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Solution Overview
Problem
Conventional lithium-ion batteries experience irreversible capacity loss due to lithium ion loss and solid electrolyte interphase (SEI) layer formation, leading to decreased specific energy and power, particularly with silicon-containing negative electrodes.
Innovation Solution
The use of current collectors with surface structures formed from precursor materials like polytetrafluoroethylene (PTFE), lithium fluoride (LiF), and polyvinylidene difluoride (PVdF) to control the formation of solid-state electrolyte layers, creating distinct precursor structures that chemically attach the solid-electrolyte interface layer and facilitate controlled lithium plating/stripping, reducing SEI degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional current collectors are used without surface structures, then the battery structure is simple and easy to manufacture, but irreversible capacity loss occurs due to SEI layer formation and degradation
Solution Approach 1:
The patent applies preliminary action by pre-forming surface structures on the current collector before electrode assembly. These structures (protrusions, recesses, or patterns) are created in advance using techniques like electrochemical etching, mechanical embossing, or deposition of precursor materials. During battery cycling, these pre-formed structures guide the formation and stabilization of the SEI layer, ensuring it develops in controlled locations and maintains integrity throughout operation, thereby preventing premature degradation and capacity loss.
Solution Approach 2:
The patent implements local quality by creating non-uniform surface structures at specific locations on the current collector. Different regions of the current collector surface are modified with distinct features (e.g., protrusions in some areas, recesses in others) that locally control SEI layer formation. This localized modification allows the SEI to form preferentially at certain sites while maintaining other areas for active material deposition, optimizing both capacity retention and structural stability without requiring complete surface redesign.
2Duration of action of stationary object
If surface structures are added to control SEI layer formation, then capacity loss is reduced and battery stability is enhanced, but manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by modifying the physical or chemical parameters of the current collector surface rather than adding entirely new components. Techniques include changing surface roughness parameters, altering surface energy through chemical treatment, or modifying surface topology via controlled deposition. These parameter modifications enable SEI layer control while using existing manufacturing infrastructure, thereby extending battery cycle life without proportionally increasing manufacturing complexity.
Solution Approach 2:
The patent uses intermediary materials or processes to bridge the gap between simple current collector fabrication and advanced SEI control. For example, a thin precursor layer (such as aluminum oxide, lithium fluoride, or organic coating) is deposited on the current collector as an intermediary that facilitates controlled SEI formation. This intermediary layer can be applied using conventional coating techniques, then thermally or electrochemically treated to create the desired surface structures, extending battery life through controlled SEI formation while maintaining ease of manufacture.
3Reliability
If precursor materials with low ionic conductivity are used for surface structures, then SEI layer formation is controlled and degradation is prevented, but ionic transport may be hindered
Solution Approach 1:
The patent implements local quality by assigning different ionic conductivity characteristics to different regions or depths of the surface structures. The precursor material may have low ionic conductivity at the surface level where SEI formation is controlled, while maintaining higher conductivity in deeper layers or specific pathways that facilitate lithium ion transport. This spatial differentiation of ionic conductivity allows simultaneous achievement of SEI stability and adequate ionic transport.
Solution Approach 2:
The patent employs porous structures formed from precursor materials that provide controlled ionic transport pathways. The porous architecture allows lithium ions to navigate through the surface structures via defined channels, maintaining effective ionic conductivity despite the low bulk conductivity of the precursor material. The porosity creates a network of conductive paths that reconcile the need for low surface conductivity (for SEI control) with the need for adequate ionic transport (for battery performance).
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 minimizes irreversible capacity loss and enhances the stability and performance of lithium-ion batteries by preventing premature SEI cracking and degradation, maintaining battery efficiency over cycles.
Implementation Method 1
creating distinct precursor structures that chemically attach the solid-electrolyte interface layer
Implementation Method 2
The electrolyte is suitable for conducting lithium ions (or sodium ions in the case of sodium-ion batteries, or potassium ions in the case of potassium-ion batteries, or magnesium ions in the case of magnesium-ion batteries, or the like) between the electrodes
Implementation Method 3
Concurrent with the insertion of the lithium ions into the electroactive material is an electrochemical reduction reaction that occurs at the electroactive material
Data Source
AI summary
The present disclosure provides an electrochemical cell that includes an electrically conductive material layer, a precursor material disposed on or adjacent to a first surface of the electrically conductive material layer, and an electroactive material layer disposed on or adjacent to the precursor material. In certain variations, the precursor material forms a continuous layer and a solid-electrolyte interface layer is disposed on or adjacent to an exposed surface of the electroactive material layer. In other variations, the precursor material forms a plurality of distinct precursor structures disposed on the first surface of the electrically conductive material layer in a predetermined pattern, such that at least a portion of each distinct precursor structure is unobstructed by the electroactive material layer. The distinct precursor structures are configured to form surface structures that chemically attach the solid-electrolyte interface layer and the electrically conductive material layer.