3D Porous Current Collector With Lithiophilic Gradient for Lithium Deposition
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Solution Overview
Problem
The insufficient lithiophilic sites on current collectors in lithium metal batteries lead to high nucleation overpotential, localized lithium deposition, severe volume expansion, rapid dendrite growth, and safety risks due to short circuits.
Innovation Solution
A current collector with a porous three-dimensional framework and lithiophilic substance distributed in its pores, featuring a gradient thickness of the lithiophilic substance from the separator side to the electrode side, reducing nucleation overpotential and promoting lithium deposition in the pores.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a metal framework is used as current collector, then the structural strength is improved, but the lithiophilic sites are insufficient and lithium nucleation overpotential is large
Solution Approach 1:
The current collector uses a composite structure combining a metal framework (Cu, Ni, Ti, Mg, or Al) with a lithiophilic substance coating layer. The metal framework provides structural strength while the lithiophilic coating layer (containing Li, Si, B, P, or their compounds) provides sufficient lithiophilic sites to reduce lithium nucleation overpotential, resolving the contradiction between mechanical strength and electrochemical performance.
Solution Approach 2:
The current collector employs a porous three-dimensional framework structure with controlled porosity (50-90%). This porous structure increases the surface area and provides more nucleation sites for lithium deposition, reducing lithium nucleation overpotential while maintaining structural integrity through the 3D framework architecture.
2Ease of manufacture
If lithium metal is deposited locally on the current collector surface, then the deposition process is simple, but severe volume expansion and dendrite growth occur
Solution Approach 1:
The lithiophilic substance is selectively distributed on the current collector surface with a gradient concentration profile, where the mass proportion of lithiophilic substance on the separator side is less than on the electrode side. This non-uniform distribution guides lithium to deposit preferentially in specific regions (pores and valleys), promoting uniform deposition throughout the 3D structure rather than localized surface deposition, thereby reducing volume expansion and dendrite formation.
Solution Approach 2:
The invention transitions from two-dimensional surface deposition to three-dimensional volumetric deposition within the porous framework. The porous 3D structure with pore sizes of 1-100 μm provides internal volume for lithium accommodation, distributing lithium deposition throughout the bulk structure rather than concentrating it on the surface, which mitigates volume expansion and prevents dendrite penetration.
3Ease of manufacture
If the lithiophilic substance is uniformly distributed, then the manufacturing process is simple, but the pores of the three-dimensional current collector cannot be fully utilized
Solution Approach 1:
The lithiophilic substance exhibits gradient distribution within the porous framework, with varying mass proportions at different locations (less on separator side, more on electrode side). This localized variation optimizes lithium deposition patterns to fully penetrate and utilize the 3D porous structure, ensuring efficient use of available pore volume while maintaining manufacturability through controlled deposition processes.
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 lithium atom diffusion, suppresses dendrite formation, limits volume expansion, and improves the safety and cycle performance of the secondary battery.
Implementation Method 1
disposing the lithiophilic substance in the pores of the porous three-dimensional framework, the nucleation overpotential of lithium on the surface of the porous three-dimensional framework can be reduced
Implementation Method 2
the diffusion capability of lithium atoms on the surface of the porous three-dimensional framework can be improved
Implementation Method 3
the lithiophilic substance increases in gradient from the side closer to the separator to the electrode, which may induce preferential deposition of lithium metal in the porous three-dimensional framework
Data Source
AI summary
A current collector may include a porous three-dimensional framework and a lithiophilic substance, where the lithiophilic substance may be distributed in pores of the porous three-dimensional framework. The current collector may include a first side used to face the separator, and a second side facing away from the first side. In a direction from the first side to the second side, the porous three-dimensional framework may include a first part and a second part, the thickness of the lithiophilic substance in the pores of the first part being less than the thickness of the lithiophilic substance in the pores of the second part. The thickness of the lithiophilic substance in the current collector may gradually increase in a thickness direction of the porous three-dimensional framework.