Multilayer Lithium Battery Anode for Fast Charging and Stability
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Solution Overview
Problem
Existing rechargeable lithium batteries face challenges in achieving high energy density, high capacity, and stability, particularly in their negative electrodes.
Innovation Solution
A multilayered negative electrode structure is introduced, comprising a first, second, and third active material layers made of crystalline carbons with varying degrees of divergence (DD) values, optimized for lithium ion conductivity and adhesion, and incorporating a silicon-containing particle layer to manage volume changes during charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single-layer negative electrode structure is used, then the device complexity is low, but the capacity and charge/discharge rate are limited
Solution Approach 1:
The negative electrode active material layer is segmented into three distinct layers (first, second, and third layers) with different crystalline carbon types and DD values. This segmentation allows each layer to perform specific functions: the first layer provides adhesion with the current collector, the second layer serves as a buffer for volume changes, and the third layer enhances lithium ion conductivity, collectively improving charge/discharge rate while maintaining structural integrity.
Solution Approach 2:
Each layer of the negative electrode is assigned different local qualities through varying the types of crystalline carbon and DD values. The first layer uses crystalline carbon with DD 5-20 for strong adhesion, the second layer uses crystalline carbon with DD 20-40 for volume buffering, and the third layer uses crystalline carbon with DD 40-60 for high lithium ion conductivity. This local differentiation optimizes overall electrode performance.
2Quantity of substance
If high capacity materials are used in the negative electrode, then the capacity increases, but the stability and structural integrity deteriorate due to volume changes during charging
Solution Approach 1:
The second layer of crystalline carbon with intermediate DD values (20-40) acts as a buffer layer that anticipates and accommodates volume changes occurring during lithium ion insertion and extraction. This pre-configured cushioning layer prevents structural damage to the electrode, maintaining stability while allowing high capacity materials in the third layer to function effectively.
Solution Approach 2:
The negative electrode employs a composite structure combining three different types of crystalline carbon materials with progressively increasing DD values. This composite architecture leverages the complementary properties of each material: adhesion from the first layer, volume buffering from the second layer, and high capacity with structural stability from the third layer, achieving both high capacity and stability simultaneously.
3Reliability
If the negative electrode structure is optimized for high lithium ion conductivity, then the charge/discharge rate improves, but the adhesion to current collector and structural stability may be compromised
Solution Approach 1:
The negative electrode is segmented into three layers with progressively increasing DD values, where each layer specializes in a particular function. The first layer with low DD (5-20) ensures strong adhesion to the current collector, while the third layer with high DD (40-60) provides superior lithium ion conductivity. This functional segmentation allows the electrode to achieve both strong adhesion and high conductivity without compromise.
Solution Approach 2:
Different local qualities are assigned to different layers: the first layer has low DD for maximum adhesion strength, the second layer has intermediate DD for structural buffering, and the third layer has high DD for optimal lithium ion conductivity. This local quality differentiation enables the electrode to simultaneously satisfy multiple competing requirements for adhesion and conductivity.
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 multilayered structure enhances lithium ion conductivity, maintains stability, and improves charge/discharge rates while reducing direct-current internal resistance.
Implementation Method 1
positive and negative electrodes include an active material in which intercalation and deintercalation are possible, and generates electrical energy caused by oxidation and reduction reactions when lithium ions are intercalated and deintercalated
Implementation Method 2
The multilayered structure enhances lithium ion conductivity, maintains stability, and improves charge/discharge rates
Implementation Method 3
generates electrical energy caused by oxidation and reduction reactions when lithium ions are intercalated and deintercalated
Implementation Method 4
generates electrical energy caused by oxidation and reduction reactions when lithium ions are intercalated and deintercalated
Data Source
AI summary
Disclosed are negative electrodes and rechargeable lithium batteries including the same. The negative electrode includes a negative electrode current collector, and a negative electrode active material layer on the negative electrode current collector. The negative electrode active material layer includes a first active material layer, a second active material layer, and a third active material layer that are sequentially stacked on the negative electrode current collector. The first, second, and third active material layers include first, second, and third crystalline carbons, respectively. The first active material layer is a random orientation layer whose degree of divergence (DD) value is about 5 to about 20. The third active material layer may be an orientation layer whose DD value is about 20 to about 60.