Polymer Current Collector With Resistivity Gradient for Lithium Deposition
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Solution Overview
Problem
Lithium metal batteries face safety and cycle life issues due to the formation of lithium dendrites during deposition, which is not effectively addressed by existing technologies.
Innovation Solution
A polymer current collector with a conductivity gradient is developed, where the resistivity of the polymer film layers is carefully controlled to induce lithium metal deposition from a low conductivity side to a high conductivity side, avoiding surface deposition and enhancing cycle life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium metal is used as the negative electrode to achieve high theoretical specific capacity, then energy density is improved, but lithium dendrite formation occurs causing safety and cycle life issues
Solution Approach 1:
The current collector is designed with non-uniform resistivity distribution, creating different local electrical properties. The first polymer film layer has higher resistivity than the second polymer film layer, forming a resistivity gradient that locally controls lithium ion deposition behavior and prevents dendrite formation in critical areas.
Solution Approach 2:
The patent changes the electrical resistivity parameter of the current collector by using polymer films with different resistivities. This parameter change creates a resistivity gradient that alters the lithium ion deposition pattern, guiding uniform deposition and preventing dendrite formation while maintaining high capacity.
2Quantity of substance
If lithium ions deposit on the surface of the current collector, then capacity is achieved, but safety risks increase due to dendrite formation
Solution Approach 1:
The current collector employs layers with different resistivity qualities to create distinct local deposition environments. The higher resistivity first layer and lower resistivity second layer work together to guide lithium ions toward uniform subsurface deposition rather than hazardous surface deposition.
Solution Approach 2:
The polymer film layers act as intermediaries between the lithium ions and the current collector substrate. The resistivity gradient in these intermediary layers controls the electric field distribution, mediating the deposition process to achieve uniform lithium metal formation without direct surface contact that would cause dendrites.
3Ease of manufacture
If a uniform current collector is used, then manufacturing is simple, but lithium deposition is non-uniform causing dendrites
Solution Approach 1:
The current collector is segmented into multiple polymer film layers with different resistivity characteristics. This segmentation allows precise control over electrical field distribution and lithium ion flux, achieving uniform deposition without significantly complicating the manufacturing process, as each layer can be produced separately and then laminated.
Solution Approach 2:
The patent uses composite material structure consisting of multiple polymer film layers with different resistivities. This composite approach combines the benefits of different materials to achieve both manufacturability and precise control over lithium deposition uniformity, leveraging the complementary properties of each layer.
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 polymer current collector effectively prevents lithium ion deposition on the surface, leading to improved cycle life and safety of lithium metal batteries by ensuring uniform and compact lithium metal deposition.
Implementation Method 1
a resistivity of the first polymer film layer is denoted as ρ1, a resistivity of the second polymer film layer is denoted as p2, and the current collector satisfies ρ1 > p2
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A polymer current collector, comprising a polymer film layer. The polymer film layer comprises a first polymer film layer and a second polymer film layer. The electrical resistivity of the first polymer film layer is denoted as ρ1. The electrical resistivity of the second polymer film layer is denoted as p2. The current collector satisfies: ρ1 > p2. The present polymer current collector is capable of inducing lithium metal deposition from a side having low electrical conductivity to a side having high electrical conductivity, avoiding the risk of lithium ion deposition on the surface of the current collector, thereby increasing the cycle life of a lithium metal battery..