Multi-Layer Negative Electrode for Lithium Dendrite Suppression
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Solution Overview
Problem
Lithium metal batteries face challenges with dendrite formation, low cycle life, and reduced energy density due to the expansion and contraction of anode materials during lithiation, which leads to mechanical instability and reductive decomposition of the solid-state electrolyte, especially during high-pressure assembly and high current densities.
Innovation Solution
A negative electrode with a current collector coated with multiple layers of metals and alloys arranged in a specific lithiation potential gradient, where the innermost layer is zinc or its alloys and the outermost layer is bismuth or its alloys, allowing for uniform lithium deposition and suppressing dendrite formation by maintaining lithium alloys during cycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If metallic lithium is used in the negative electrode, then high energy density is achieved, but dendrite formation occurs and cycle life is reduced
Solution Approach 1:
The negative electrode is segmented into multiple functional layers: a first layer containing metallic lithium particles dispersed in a conductive matrix, and a second layer containing lithium alloy particles with higher lithiation potential. This segmentation allows the system to maintain high energy density from the lithium metal while the alloy layer suppresses dendrite formation, resolving the contradiction between energy density and cycle life.
Solution Approach 2:
The lithium alloy layer acts as an intermediary between the metallic lithium layer and the electrolyte. This intermediate layer with higher lithiation potential regulates lithium ion flux, preventing direct contact between lithium metal and electrolyte that would cause dendrite formation, thus improving cycle life while preserving the high energy density of the lithium metal layer.
2Productivity
If high current density is applied during charging, then charging speed is improved, but dendrite formation increases
Solution Approach 1:
The invention changes the electrochemical parameters of the negative electrode by introducing materials with different lithiation potentials. The lithium alloy layer has a higher lithiation potential than metallic lithium, creating a potential gradient that regulates lithium ion deposition. This parameter change allows the system to accept high current densities during charging while the potential gradient prevents dendrite formation, simultaneously improving charging speed and reliability.
3Quantity of substance
If anode materials undergo expansion during lithiation, then lithium capacity is increased, but mechanical instability occurs
Solution Approach 1:
The negative electrode uses a composite structure combining metallic lithium particles with a conductive matrix material, and lithium alloy particles with higher lithiation potential. The composite structure allows the system to achieve high lithium capacity through the lithium metal while the alloy component and matrix provide mechanical stability, preventing pulverization during expansion and contraction cycles.
4Reliability
If solid-state electrolyte is used, then safety is improved, but reductive decomposition occurs at the interface
Solution Approach 1:
The invention applies preliminary action by using the lithium alloy layer with higher lithiation potential to form a stable interface with the solid-state electrolyte before the metallic lithium layer can cause reductive decomposition. The alloy layer reacts first during initial cycling to create a protective interface, preventing subsequent harmful reactions between the lithium metal and electrolyte, thus maintaining safety while preventing decomposition.
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 suppresses dendrite formation, enhances cycle life, and achieves high energy density by maintaining lithium alloys and preventing reductive decomposition of the solid-state electrolyte, allowing for high-pressure assembly and increased current densities without short-circuiting.
Implementation Method 1
the n layers are arranged so that layer (i+1) has a higher potential of lithiation than that of layer (i) which is immediately beneath it
Implementation Method 2
uniform lithium deposition and suppressing dendrite formation by maintaining lithium alloys during cycling
Implementation Method 3
both electrodes intercalate/deintercalate Lithium Ions
Implementation Method 4
maintaining lithium alloys during cycling
Data Source
Figure 1~1D
Figure 2~2B
Figure 3~3C
AI summary
The present invention concerns a negative electrode comprising multiple coated layers to prevent dendrite formation, the process for manufacturing said electrodes and the electrochemical cells and batteries comprising the same.