Negative Electrode Functional Layer for Faster Lithium-Ion Diffusion
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Solution Overview
Problem
Current rechargeable lithium batteries face challenges in achieving high energy density and efficient lithium ion diffusion, leading to limitations in cycle-life and rate capability due to low active mass density and lithium ion precipitation issues.
Innovation Solution
Incorporating a functional layer with nanometal and nanocarbon between or on the negative active material layer of the negative electrode, which enhances lithium ion diffusion and prevents surface precipitation, improving capacity and cycle-life characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional negative electrode structure is used, then the device complexity is low, but the lithium ion diffusion rate is insufficient and cycle-life is poor
Solution Approach 1:
The negative electrode is segmented into multiple functional layers: a current collector, a negative active material layer, and an intermediate functional layer containing nanometal and nanocarbon. This segmentation allows each layer to perform its specific function optimally, improving lithium ion diffusion and cycle-life while managing the complexity through modular design
Solution Approach 2:
An intermediate functional layer is introduced between the current collector and the negative active material layer. This intermediary layer contains nanometal particles and nanocarbon that facilitate lithium ion diffusion and prevent direct contact between the active material and current collector, thereby improving cycle-life and preventing degradation
2Quantity of substance
If the active mass density is increased, then the energy density is improved, but lithium ion precipitation occurs on the surface
Solution Approach 1:
The functional layer acts as an intermediary between the high-density active material and the electrolyte, providing nucleation sites for lithium ion deposition through nanometal and nanocarbon. This prevents direct precipitation on the active material surface while allowing high active mass density to be maintained
Solution Approach 2:
The functional layer incorporates porous nanocarbon structures and dispersed nanometal particles that provide a large surface area with controlled porosity. This porous structure facilitates uniform lithium ion distribution and prevents localized precipitation even when high amounts of active material are used
3Speed
If the functional layer thickness is increased, then the lithium ion diffusion is improved, but the active mass density decreases
Solution Approach 1:
The thickness of the functional layer is optimized to a specific range (50 nm to 20 μm) to balance lithium ion diffusion performance and active mass density. Within this optimized parameter range, sufficient diffusion pathways are provided without excessively reducing the proportion of active material in the electrode structure
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 integration of nanometal and nanocarbon in the functional layer improves lithium ion diffusion rates, prevents lithium ion precipitation, and enhances the capacity and cycle-life of rechargeable lithium batteries, maintaining high performance even after multiple charge and discharge cycles.
Implementation Method 1
enhances lithium ion diffusion
Implementation Method 2
nanometal and nanocarbon in the functional layer improves lithium ion diffusion rates
Implementation Method 3
prevents surface precipitation
Data Source
AI summary
A negative electrode and a rechargeable lithium battery including the negative electrode, the negative electrode including a current collector, a negative active material layer, and a functional layer between the current collector and the negative active material layer or on the negative active material layer, the functional layer including nanometal and nanocarbon.