Dual-Layer SiO Electrode for Battery Stress Management
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Solution Overview
Problem
Existing non-aqueous electrolyte secondary battery electrodes face issues with peeling and deformation due to differences in expansion coefficients between the current collector, intermediate layers, and electrode active material layers, leading to inadequate cycle characteristics.
Innovation Solution
A dual-layer electrode structure is introduced, with a first active material layer having a higher oxygen concentration than the second active material layer, where the first layer is in contact with the current collector and the second layer consists of active material particles with a lower oxygen concentration, reducing stress on the current collector and enhancing adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-layer electrode active material layer is formed directly on the current collector, then the electrode structure is simple and manufacturing is easy, but the electrode active material layer peels from the current collector due to expansion/contraction stress during charge-discharge cycles
Solution Approach 1:
The electrode active material layer is divided into two distinct layers: a first electrode active material layer in contact with the current collector and a second electrode active material layer on top. This segmentation allows each layer to have different compositions optimized for their specific functions - the first layer provides stress buffering and adhesion while the second layer provides high capacity
Solution Approach 2:
The first electrode active material layer acts as an intermediate layer between the current collector and the second electrode active material layer. This intermediate layer buffers the expansion/contraction stress, preventing direct transmission to the current collector and eliminating peeling issues
2Quantity of substance
If the electrode active material layer is made thick to increase capacity, then the battery capacity increases, but the expansion/contraction stress increases causing more severe peeling and deformation
Solution Approach 1:
By dividing the thick electrode active material layer into two sub-layers, the stress is distributed and managed more effectively. The first layer close to the current collector experiences and buffers the stress, while the second layer provides the additional capacity without causing proportional increase in peeling stress
Solution Approach 2:
Different regions of the electrode active material have different compositions - the first layer has composition optimized for stress management and adhesion, while the second layer has composition optimized for high capacity. This local differentiation allows the system to achieve high overall capacity while maintaining reliability
3Reliability
If an intermediate layer is added between the current collector and electrode active material layer to prevent peeling, then adhesion improves, but the electrode structure becomes more complex and manufacturing difficulty increases
Solution Approach 1:
The first electrode active material layer serves multiple functions simultaneously: it acts as an intermediate layer for stress buffering, provides additional active material for capacity, and maintains adhesion to the current collector. This multi-functionality reduces the need for separate specialized layers
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 alleviates stress on the current collector, suppresses peeling and deformation, and improves charge-discharge cycle characteristics of the battery.
Implementation Method 1
an electrode active material layer which contains silicon (Si), germanium (Ge), tin (Sn), or the like is formed on a current collector... when occluding or releasing lithium ions... expansions and contractions that accompany repetitive charge and discharge
Implementation Method 2
expansions and contractions of the electrode active material due to charge and discharge may cause problems such as peeling of the electrode active material layer from the current collector... differences in expansion coefficients between the current collector, intermediate layers, and electrode active material layers
Data Source
AI summary
An electrode for a non-aqueous electrolyte secondary battery 6 according to the present invention includes: a current collector 3; a first active material layer 2 formed on the current collector 3; and a second active material layer 5 provided on the first active material layer 2, the second active material layer 5 including a plurality of active material particles 4. The plurality of active material particles 4 is mainly of a chemical composition represented as SiOx (0≦x<1.2). The first active material layer 2 is mainly of a chemical composition represented as SiOy (1.0≦y<2.0, y>x). The area in which the first active material layer 2 is in contact with the plurality of active material particles 4 is smaller than the area in which the current collector 3 is in contact with the first active material layer 2.