Multi-Layered Anode Structure for Lithium Secondary Battery
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Solution Overview
Problem
Lithium secondary batteries face challenges with silicon-based anode active materials that cause shrinkage and expansion during charge/discharge cycles, leading to peel-off of the anode active material layer and side reactions with the electrolyte, which affect capacity and stability.
Innovation Solution
A multi-layered anode structure is introduced, comprising a first anode active material layer of artificial graphite and a second anode active material layer containing silicon-based materials and carbon nanotubes, with the silicon-based material content ranging from 9 to 30 wt%, to enhance capacity and stability by promoting lithiation and reducing structural instability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based active material is used to increase capacity, then high-capacity property is improved, but shrinkage/expansion causes peel-off and structural instability
Solution Approach 1:
The anode active material layer is divided into multiple layers with different compositions and functions. The first layer (closest to current collector) uses graphite-based material for structural stability, the second layer uses silicon-based material for high capacity, and intermediate layers facilitate lithium ion transport. This segmentation allows each layer to perform its specific function while working together to resolve the contradiction between capacity and stability.
Solution Approach 2:
The patent employs composite material structures where graphite-based materials and silicon-based materials are combined in a multi-layer configuration. The graphite layers provide structural framework and stability, while silicon layers contribute high capacity. This composite approach enables the anode to simultaneously achieve both structural stability and high capacity by leveraging the complementary properties of different materials.
2Quantity of substance
If silicon-based active material is used to increase capacity, then high-capacity property is improved, but peel-off of anode active material layer occurs
Solution Approach 1:
The anode is segmented into multiple functional layers where the first layer (graphite-based) serves as a stable foundation bonded to the current collector, and the second layer (silicon-based) provides high capacity. This segmentation prevents peel-off by creating a gradient structure where each layer is optimized for its specific role, with intermediate layers facilitating smooth lithium ion transport and stress distribution.
Solution Approach 2:
Different regions of the anode are assigned different material compositions and properties. The first layer near the current collector uses graphite-based material with high bonding strength and structural stability, while the second layer uses silicon-based material for high capacity. This local differentiation of material properties ensures that each region performs its specific function optimally while maintaining overall structural integrity.
3Duration of action of stationary object
If multi-layered structure is introduced to improve stability, then life-span stability is improved, but device complexity increases
Solution Approach 1:
The anode active material layer is segmented into multiple functional layers, each with specific compositions and roles. This segmentation, while increasing structural complexity, enables improved life-span stability by distributing mechanical stress and preventing peel-off across multiple interfaces. The segmented structure allows for optimized lithium ion transport pathways and better accommodation of expansion/contraction cycles.
Solution Approach 2:
The multi-layered structure serves multiple functions simultaneously: the graphite-based first layer provides structural stability and bonding to the current collector, the intermediate layers facilitate lithium ion transport, and the silicon-based second layer provides high capacity. This multi-functionality justifies the increased structural complexity by delivering comprehensive performance improvements in stability, capacity, and cycle life.
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 multi-layered anode structure improves the high-capacity property of silicon-based active materials while maintaining sufficient life-span stability, preventing peel-off and structural degradation, and maintaining capacity retention even with high silicon-based material content.
Implementation Method 1
The second anode active material layer includes a second anode active material including a silicon-based active material and carbon nanotube as a second conductive material
Implementation Method 2
The first anode active material layer includes a first anode active material including artificial graphite
Data Source
AI summary
Provided is an anode for a lithium secondary battery including an anode electrode current collector; a first anode active material layer formed on a surface of the anode current collector, and a second anode active material layer formed on the first anode material layer. The first anode active material layer includes first anode active material including artificial graphite and a first conductive material that is a carbon-based material except for carbon nanotube. The second anode active material layer includes a second anode active material including a silicon-based active material and carbon nanotube as a second conductive material.