Dual-Layer Negative Electrode Assembly for Silicon Expansion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The volume change of silicon-based active materials in negative electrodes of rechargeable batteries leads to ruptures and capacity reduction, particularly in lithium rechargeable batteries, due to their larger expansion and contraction during charging and discharging.
Innovation Solution
The electrode assembly design includes a negative electrode with two active material layers on opposite surfaces, where the first layer has a higher content of silicon-based active material and carbon nanotubes to withstand compressive stress, while the second layer has a lower content of silicon-based active material and carbon nanotubes to manage tensile stress, thereby reducing volume change and maintaining capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based active material is used in the negative electrode to increase capacity, then the capacity of the negative electrode is improved, but the volume change during charging and discharging increases causing rupture
Solution Approach 1:
The negative electrode is divided into multiple layers (first negative active material layer and second negative active material layer) with different compositions and functions. The first layer contains silicon-based active material for high capacity, while the second layer contains carbon-based active material to constrain volume change, thereby resolving the contradiction between capacity and structural integrity through functional segmentation.
2Ease of manufacture
If uniform composition is used in both surfaces of negative electrode, then manufacturing is simplified, but volume change cannot be effectively managed
Solution Approach 1:
Different regions of the negative electrode are assigned different compositions: the first negative active material layer on one surface contains silicon-based active material for high capacity, while the second negative active material layer on the other surface contains carbon-based active material for volume stability. This local differentiation allows effective management of volume change while maintaining manufacturability through a systematic coating process.
Data Source
AI summary
An electrode assembly of a rechargeable battery includes a separator, and a positive electrode and a negative electrode with the separator interposed therebetween, the positive electrode and the negative electrode being wound together with the separator. The negative electrode may include a negative substrate, a first active material layer disposed on one surface of the negative substrate, and a second active material layer disposed on the other surface of the negative substrate. The first active material layer may include a carbon-based active material, a silicon-based active material, and a carbon nanotube. The second active material layer may include the carbon-based active material.