Porous Microgel Negative Electrode for Thick Li-Ion Battery Anodes
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Solution Overview
Problem
Rechargeable lithium batteries face challenges in improving energy density and high-rate characteristics due to electrode thickening, which increases ion resistance and deteriorates performance.
Innovation Solution
A negative electrode with a microgel of 500 nm or less in size and 27% to 60% porosity, made from an acryl-based polymer, is integrated into the active material layer to enhance lithium-ion transportation and reduce electrical resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If electrode thickness is increased to improve energy density, then capacity is improved, but ion resistance increases and high-rate characteristics deteriorate
Solution Approach 1:
The patent introduces a porous coating layer on the electrode surface with controlled porosity (30-70%) and pore size (0.5-5 μm). This porous structure provides ion transport pathways that reduce ion resistance, allowing the electrode to maintain high-rate characteristics even when thickened for improved energy density.
Solution Approach 2:
The patent applies different properties to different regions: the bulk electrode is thickened for high capacity, while the surface coating layer is designed with specific porosity and pore size to facilitate ion transport. This local differentiation allows the electrode to simultaneously achieve high energy density and good high-rate characteristics.
2Quantity of substance
If electrode thickness is increased to improve energy density, then capacity is improved, but ion resistance increases
Solution Approach 1:
The porous coating layer with 30-70% porosity creates multiple ion transport pathways on the electrode surface, significantly reducing ion resistance. The controlled pore size (0.5-5 μm) optimizes the balance between ion transport efficiency and electrode structural integrity.
Solution Approach 2:
The patent adds a surface coating dimension to the traditional bulk electrode structure. This additional dimensional feature provides alternative ion transport routes that bypass the resistance issues inherent in thick electrodes, effectively reducing ion resistance without compromising energy density.
3Speed
If microgel size is reduced to improve lithium-ion transportation, then high-rate characteristics are improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies a microgel size range (500 nm or less, preferably 100-500 nm) that optimizes lithium-ion transportation speed while remaining manufacturable. This parameter optimization balances performance improvement with manufacturing feasibility, avoiding excessively tight tolerances.
Solution Approach 2:
The microgels create a porous network structure that facilitates rapid lithium-ion diffusion. The specific size range (100-500 nm) provides sufficient porosity for fast ion transport while maintaining structural stability and ease of incorporation into the electrode matrix.
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 solution improves high-rate charging characteristics and cycle life by maintaining porosity and uniform distribution of the microgel, leading to better energy density and performance.
Implementation Method 1
a microgel having a size of about 500 nm or less, and having a porosity of about 27% to about 60%
Data Source
AI summary
Disclosed herein is a negative electrode for a rechargeable lithium battery and a rechargeable lithium battery including the same, wherein the negative electrode includes a current collector and a negative active material layer on at least one surface of the current collector, and the negative active material layer includes a negative active material and a microgel having a size of about 500 nm or less, and having porosity of about 27% to about 60%.