Layered Lithium Metal Anode Structure for Dendrite Suppression
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Solution Overview
Problem
Lithium metal deposition in lithium secondary batteries results in non-uniform growth of lithium nuclei, leading to dendrite formation, which causes electrode expansion, reduces safety, and deteriorates cycle characteristics.
Innovation Solution
A lithium secondary battery design featuring a negative electrode with a current collector layer, a first lithium metal layer, a second granular lithium metal layer, and a third porous lithium metal layer, along with a specific porosity and pore diameter configuration, and a production method involving controlled charging and discharging cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium metal is used as negative electrode active material to achieve high capacity, then battery capacity increases significantly, but lithium metal deposits non-uniformly forming dendrites that deteriorate cycle characteristics and safety
Solution Approach 1:
The negative electrode is segmented into multiple functional layers: a first lithium metal layer providing high capacity, a second protective layer preventing direct contact between lithium and electrolyte, and a third porous layer controlling deposition uniformity. This segmentation resolves the contradiction by isolating the high-capacity lithium metal from conditions causing non-uniform deposition while maintaining its capacity benefits
Solution Approach 2:
A second protective layer is introduced as an intermediary between the lithium metal layer and electrolyte, preventing direct contact that causes non-uniform deposition and dendrite formation. This intermediary layer maintains the high capacity of lithium metal while eliminating the harmful deposition patterns that deteriorate cycle characteristics
2Shape
If lithium metal is deposited non-uniformly, then dendritic lithium metal forms with increased specific surface area, but reductive decomposition products increase and negative electrode expands
Solution Approach 1:
Different regions of the negative electrode are given different properties: the first layer provides high lithium content for capacity, the second layer provides protective properties to prevent non-uniform deposition, and the third layer provides porous structure for uniform ion distribution. This local differentiation ensures uniform lithium deposition morphology while preventing the generation of reductive decomposition products and electrode expansion
3Area of moving object
If dendrite formation proceeds, then specific surface area increases leading to more reductive decomposition, but electrode expansion promotes electrolyte depletion and reduces safety
Solution Approach 1:
The third porous layer, which could potentially increase surface area and promote decomposition, is instead used beneficially to provide uniform lithium ion distribution and control deposition morphology. The porosity enables uniform ion flux that prevents dendrite formation, converting what could be a harmful increased surface area into a benefit for uniform deposition and electrolyte management
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 design suppresses non-uniform lithium metal growth, improving cycle characteristics and safety by preventing dendrite formation and maintaining electrode integrity.
Implementation Method 1
a third lithium metal layer including lithium metal and being porous... the granular lithium metal having an average particle diameter larger than an average pore diameter of the third lithium metal layer
Implementation Method 2
a lithium secondary battery performs charging and discharging by depositing and dissolving lithium metal
Data Source
Figure 1
Figure 2
Figure 3(a)~3(c)
AI summary
A lithium secondary battery according to an embodiment is a lithium secondary battery including a negative electrode and a positive electrode, in which the negative electrode has: in the following order, a current collector layer; a first lithium metal layer made of a lithium metal foil; a second lithium metal layer including granular lithium metal; and a third lithium metal layer including lithium metal and being porous, the granular lithium metal having an average particle diameter larger than an average pore diameter of the third lithium metal layer.