Polymer Current Collector Conductivity Gradient for Lithium Deposition
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Solution Overview
Problem
Lithium metal batteries face safety and cycle life constraints due to the formation of lithium dendrites during deposition, which affects their electrochemical performance and rapid popularization.
Innovation Solution
A polymer current collector with a conductivity gradient is introduced, comprising multiple polymer film layers with varying resistivities, where the resistivity of the first layer is greater than the second layer, preventing lithium ions from depositing on the surface and promoting uniform lithium metal deposition.
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 dendrites are formed during deposition which reduces safety and cycle life
Solution Approach 1:
The current collector is designed with non-uniform conductivity distribution, creating different local electrical properties across its structure. The first region has higher conductivity while the second region has lower conductivity, which guides lithium ion deposition to occur preferentially in the lower conductivity region, preventing dendrite formation while maintaining overall battery performance
Solution Approach 2:
The patent changes the conductivity parameter of the current collector by using different materials or structures in different regions. The conductivity ratio between the first and second regions is controlled within 0.1 to 10, creating a gradient that directs lithium deposition behavior and prevents harmful dendrite growth
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 is designed with non-uniform conductivity distribution, creating different local electrical properties across its structure. The first region has higher conductivity while the second region has lower conductivity, which guides lithium ion deposition to occur preferentially in the lower conductivity region, preventing dendrite formation while maintaining overall battery performance
Solution Approach 2:
The current collector acts as an intermediary structure between the electrolyte and the lithium deposition site. By designing it with varying conductivity regions, it mediates the lithium ion flow and deposition process, directing ions to deposit in the lower conductivity region rather than forming dendrites on high conductivity surfaces
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 increases the cycle life of lithium metal batteries by inducing lithium metal deposition from a low to high conductivity side, reducing the risk of surface deposition and enhancing battery performance.
Implementation Method 1
a polymer current collector with a conductivity gradient is introduced, comprising multiple polymer film layers with varying resistivities, where the resistivity of the first layer is greater than the second layer
Data Source
AI summary
This application provides a polymer current collector, a preparation method thereof, and a secondary battery, battery module, battery pack, and apparatus associated therewith. The polymer current collector provided in this application includes polymer film layers, where the polymer film layers include a first polymer film layer and a second polymer film layer, a resistivity of the first polymer film layer is denoted as ρ1, a resistivity of the second polymer film layer is denoted as ρ2, and the current collector satisfies ρ1>ρ2. The polymer current collector in this application can induce to deposit of lithium metal from a low conductivity side to a high conductivity side, avoiding risks of depositing lithium ions on the surface of the current collector and thereby increasing cycle life of lithium metal batteries.