Layered Negative Electrode Pore Structure for High-Rate Battery Cycling
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Solution Overview
Problem
Existing secondary battery negative electrodes with small pore diameters inhibit electrolyte flow, leading to degraded cycle characteristics during high-rate charging and discharging.
Innovation Solution
A negative electrode with a multi-layer structure, where the first mixture layer has a reduced pore diameter and the second mixture layer has an increased pore diameter, creating a specific pore diameter ratio (A/B) between 0.01 and 1, enhancing electrolyte flow and cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If many pores having a small pore diameter are present in the negative electrode, then the decomposition of electrolytic solution is suppressed and cycle characteristics are improved, but the flow of electrolytic solution from the positive electrode is inhibited and high-rate charging and discharging characteristics are degraded
Solution Approach 1:
The negative electrode mixture layer is divided into two distinct layers: a first mixture layer with small pore diameter (0.03-2 μm) that suppresses electrolyte decomposition, and a second mixture layer with large pore diameter (2-10 μm) that facilitates electrolyte flow. This segmentation allows each layer to perform its specialized function, resolving the contradiction between cycle stability and high-rate performance
Solution Approach 2:
Different regions of the negative electrode are given different pore diameter characteristics tailored to their specific functions. The first mixture layer (closer to current collector) has small pores for stability, while the second mixture layer (outer layer) has large pores for rapid electrolyte access. This local differentiation optimizes both cycle characteristics and high-rate charging/discharging performance
2Reliability
If the pore diameter is reduced to improve cycle characteristics, then the decomposition of electrolytic solution is suppressed, but the flow of electrolytic solution is inhibited
Solution Approach 1:
The negative electrode is segmented into two layers with different pore diameters. The first layer has small pores (0.03-2 μm) to suppress electrolyte decomposition, while the second layer has large pores (2-10 μm) to ensure adequate electrolyte supply, thus resolving the contradiction between electrolyte decomposition suppression and electrolyte flow maintenance
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
This configuration improves cycle characteristics and energy density by optimizing the flow of the electrolyte during high-rate charging and discharging, resulting in better high-rate charging and discharging performance.
Implementation Method 1
the first mixture layer and the second mixture layer have different pore diameter distributions from each other, and when a pore diameter corresponding to a maximum peak in the pore diameter distribution in the first mixture layer is defined as a pore diameter A, and a pore diameter corresponding to a maximum peak in the pore diameter distribution in the second mixture layer is defined as a pore diameter B
Data Source
AI summary
This negative electrode for a rechargeable battery, according to an exemplary embodiment, comprises: a core; and a mixture layer formed on the core. The mixture layer includes: a first mixture layer; and a second mixture layer disposed on the first mixture layer. The first mixture layer and the second mixture layer have mutually different pore size distributions. In a case where a pore size corresponding to the maximum peak of the pore size distribution of the first mixture layer is defined as pore size A and a pore size corresponding to the maximum peak of the pore size distribution of the second mixture layer is defined as pore size B, the ratio of pore size A to pore size B (A/B) is greater than 0.01 and less than 1.