Lithium Metal Coated Battery Separator for Capacity Compensation
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Solution Overview
Problem
Li batteries experience irreversible lithium loss during the first operating cycle, necessitating improved designs that can accommodate this loss.
Innovation Solution
A lithium ion battery design featuring a separator coated with a thin film of lithium metal, typically 1 to 5 microns thick, which compensates for the initial lithium loss, along with a ceramic layer and a barrier layer to prevent dendrite formation and enhance ion conductivity, fabricated using methods like physical vapor deposition and slot die deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a separator is coated with a thin film of lithium metal to compensate for irreversible lithium loss, then the battery capacity and performance are improved, but the risk of dendrite formation and internal shorting increases
Solution Approach 1:
The patent applies a non-uniform lithium metal coating on the separator where the coating density and thickness are locally optimized. The coating is applied more heavily in regions prone to lithium loss while maintaining thinner regions to prevent dendrite formation, creating spatially varying properties that balance capacity compensation with safety.
Solution Approach 2:
The patent creates a composite structure combining the separator material with lithium metal coating, forming a hybrid component that leverages the pore structure and ion conductivity of the separator while adding the high capacity of lithium metal. This composite approach enables both functions to coexist without either dominating to the detriment of the other.
2Quantity of substance
If the lithium metal coating thickness is increased to compensate for lithium loss, then the battery capacity improves, but the manufacturing precision requirements increase
Solution Approach 1:
The patent optimizes the lithium metal coating thickness parameter to a specific range (1-5 microns) that provides sufficient lithium compensation while remaining manufacturable. This parameter optimization balances the competing requirements of adequate lithium supply with the practical limitations of deposition process control.
Solution Approach 2:
The patent applies a lithium coating that is sufficient to compensate for typical lithium loss (1-5 microns) but deliberately limits it to prevent excessive accumulation that would cause manufacturing difficulties. This partial action approach provides just enough lithium compensation without over-coating, which would exacerbate manufacturing precision challenges.
3Reliability
If a lithium metal coating is deposited on the separator, then ion conductivity is enhanced, but the device complexity increases due to additional coating processes
Solution Approach 1:
The patent extracts the lithium metal coating function from a separate manufacturing step and integrates it directly onto the separator during the separator fabrication process itself. This integration eliminates the need for additional post-processing coating equipment and steps, reducing overall device complexity while maintaining the ion conductivity enhancement.
Solution Approach 2:
The patent merges the separator fabrication process with the lithium metal coating deposition process into a single integrated operation. By combining these two functions into one process step, the patent reduces the number of discrete manufacturing steps and equipment requirements, thereby reducing device complexity while achieving both separator formation and lithium coating simultaneously.
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 solution effectively mitigates lithium loss and prevents battery shorting, ensuring efficient operation by maintaining the thin lithium film on the separator and enhancing the battery's ion conductivity.
Implementation Method 1
a thin film of lithium metal having a thickness less than or equal to a thickness sufficient to compensate for the irreversible loss of lithium metal during a first cycle of the lithium ion battery
Implementation Method 2
the first module being configured for depositing the thin film of lithium metal by a process chosen from the group consisting of physical vapor deposition, electron-beam evaporation, thin film transfer and slot die deposition
Implementation Method 3
the first module being configured for depositing the thin film of lithium metal by a process chosen from the group consisting of physical vapor deposition, electron-beam evaporation, thin film transfer and slot die deposition
Data Source
AI summary
A lithium ion battery may comprise a positive electrode, a negative electrode and a separator coated with a thin film of lithium metal, the thickness of the lithium being less than or equal to a thickness sufficient to compensate for the irreversible loss of lithium during the first cycle of the battery. Furthermore, there may be a ceramic layer on the separator between the separator and the lithium metal thin film. Yet furthermore, there may be a barrier layer between the ceramic layer and the lithium metal thin film, wherein the barrier layer blocks Li dendrite formation. Furthermore, the separator may have pores which may be filled with one or more of a lithium ion-conducting polymer, a binder soluble in a liquid electrolyte, and a lithium ion-conducting ceramic material. Methods of, and equipment for, fabricating such battery separators and also for fabricating components for lithium metal based batteries are described.