Negative Electrode Collector Design for Lithium Ion Pre-doping
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Solution Overview
Problem
Conventional lithium ion capacitors face issues with low productivity and reliability due to the separate preparation and connection of a lithium collector, and the risk of voltage drop caused by fine lithium powder generated during pre-doping.
Innovation Solution
An electrochemical device design where metal lithium is joined to the negative electrode collector's uncoated region on the outermost side of winding, preventing lithium powder from reaching the positive electrode and eliminating the need for a separate lithium collector, with a copper negative electrode collector providing conductivity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate lithium collector is prepared and connected to the negative electrode collector for pre-doping lithium ions, then lithium ion pre-doping can be achieved, but productivity decreases due to additional preparation and connection processes
Solution Approach 1:
The patent combines the lithium collector and negative electrode collector into a single integrated negative electrode collector. The lithium source material is directly placed on the negative electrode collector without requiring a separate lithium collector component, thereby eliminating the connection process while maintaining lithium ion pre-doping functionality.
Solution Approach 2:
The negative electrode collector serves dual functions: it acts as both the current collector and the lithium source holder. By making the negative electrode collector multi-functional, the patent eliminates the need for a separate lithium collector while ensuring effective lithium ion pre-doping into the negative electrode active material layer.
2Reliability
If lithium is placed in a region on the negative electrode collector for pre-doping, then lithium ions can be doped into the negative electrode, but fine lithium powder may reach the positive electrode causing voltage drop
Solution Approach 1:
The patent designates a specific uncoated region on the negative electrode collector where lithium source material is placed, distinct from the regions covered by the negative electrode active material layer. This localized placement ensures lithium ions are released only where needed, preventing fine lithium powder from migrating to the positive electrode while maintaining effective pre-doping in the active material regions.
Solution Approach 2:
The negative electrode collector is segmented into different functional regions: an uncoated region for lithium source placement and coated regions with negative electrode active material layer for electrochemical reactions. This segmentation isolates the lithium source from direct contact with the positive electrode while enabling controlled lithium ion release into the active material.
3Productivity
If metal lithium is joined to the uncoated region on the outermost side of winding, then productivity increases by eliminating separate lithium collector, but structural complexity must be managed
Solution Approach 1:
The patent merges the lithium source integration into the negative electrode collector structure itself, specifically in the uncoated region on the outermost side of winding. This consolidation simplifies the overall device structure by eliminating separate lithium collector components and their connections, while the specific placement in the uncoated region manages structural complexity by providing a dedicated space for lithium without interfering with the active material layers.
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 design enhances productivity by eliminating the need for a separate lithium collector and ensures reliability by preventing voltage drops, allowing for effective pre-doping and increased capacitance without reducing the capacitor's size.
Implementation Method 1
metal lithium that releases lithium ions when in contact with the electrolytic solution
Implementation Method 2
doping lithium ions from the metal lithium into the negative electrode active material layer
Data Source
AI summary
An electrochemical device is constituted by a positive electrode, a negative electrode, and separators that are wound in such a way that the first principal face of the negative electrode and third principal face of the positive electrode are on the inner side of winding, while the second principal face of the negative electrode and fourth principal face of the positive electrode are on the outer side of winding, with the separators separating the positive electrode and negative electrode; wherein the second principal face has a first region opposed to the positive electrode via the separator and a second region on the outermost side of winding and not opposed to the positive electrode, the second region includes a first uncoated region where no negative electrode active material layer is formed, and a metal lithium is joined to the first uncoated region and immersed in electrolytic solution.