Ex-situ Lithium Anode Protective Layer Formation
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Solution Overview
Problem
Conventional lithium cells experience degradation due to the formation of dendrites and the continuous destruction of the solid electrolyte interface (SEI) layer during charging and discharging, leading to reduced anode capacity and reliability.
Innovation Solution
A method is developed to form a selective protective layer on the anode containing metallic lithium before assembly, using a first electrolyte to create a stable and robust SEI, which is further reinforced with a polymerizable material to form a second protective layer, enhancing the anode's service life and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional SEI layer forms on the anode during cell operation, then the anode becomes operational, but the layer is continuously destroyed and rebuilt causing dendrite formation and reduced reliability
Solution Approach 1:
The patent applies a first electrolyte to the anode before cell assembly to pre-form a stable protective layer. This preliminary action creates a robust SEI layer that prevents continuous destruction and rebuilding during operation, thereby eliminating dendrite formation and improving both reliability and service life.
Solution Approach 2:
The patent reinforces the protective layer by applying a polymerizable material that forms a second protective layer before the anode is assembled into the cell. This beforehand cushioning provides additional protection against mechanical stress and chemical degradation, preventing layer destruction and dendrite formation during subsequent charging and discharging cycles.
2Productivity
If the anode material and electrolyte are continuously used up due to layer destruction, then charging and discharging occur, but capacity is reduced and cell fails
Solution Approach 1:
By pre-forming a stable protective layer with the first electrolyte before cell assembly, the patent prevents continuous consumption of anode material and electrolyte. The robust SEI layer acts as a protective barrier that maintains material integrity during charging and discharging, preserving capacity and preventing cell failure.
3Reliability
If dendrites form at damaged locations, then the cell operates, but the surface morphology deteriorates and reliability is adversely affected
Solution Approach 1:
The patent pre-forms a stable protective layer before cell assembly that prevents surface morphology deterioration. By establishing a robust SEI layer in advance, the patent eliminates the conditions that lead to dendrite formation at damaged locations, maintaining smooth surface morphology and preserving reliability throughout the cell's operational life.
Solution Approach 2:
The polymerizable material applied before assembly provides beforehand cushioning that protects the anode surface from mechanical stress and prevents damage that would lead to dendrite formation. This additional protective layer maintains surface integrity and prevents morphology deterioration during cell operation.
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 results in a permanent and robust protective layer system that significantly increases the anode's capacity, service life, and reliability, while providing better shielding against external influences, compared to conventional SEI layers.
Implementation Method 1
applying a first electrolyte on an anode containing metallic lithium, so that a first protective layer is formed on the anode, especially one containing electrolytic decomposition products
Implementation Method 2
heating the system from method step a), in particular to a temperature of 30° C., for instance 50° C., for instance to 60° C. This advantageously makes it possible to facilitate the production of the first protective layer
Implementation Method 3
applying a polymerizable and/or polymer material on the first protective layer so as to form a second protective layer on the first protective layer
Data Source
AI summary
In a method for producing an anode for a lithium cell, and/or a lithium cell as well as anodes and lithium cells of this type, to extend the service life of the lithium cell and to selectively form a first protective layer including electrolytic decomposition products, on an anode including metallic lithium, a first electrolyte is applied on the anode ex situ, i.e., prior to assembling the lithium cell to be produced. To stabilize the first protective layer, a second protective layer is applied in a subsequent method step.