Silicon Anode Layering for Stable High-Energy Secondary Batteries
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Solution Overview
Problem
Silicon-based negative electrode materials in secondary batteries experience volume expansion during use, which affects cycle performance and structural stability, limiting their effectiveness.
Innovation Solution
A negative electrode plate design with a first region containing a silicon-oxygen-based material and a second region containing a silicon-carbon composite material, optimized by specific mass ratios and particle sizes, enhances structural stability and ion transport, compensating for the deficiencies of each material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If silicon-based materials are used as negative electrode active materials, then energy density is improved, but cycle performance deteriorates due to volume expansion
Solution Approach 1:
The negative electrode active material is segmented into two distinct regions: a first region containing silicon-oxygen-based material and a second region containing silicon-carbon composite material. This segmentation allows each region to contribute different properties, with the silicon-oxygen-based material providing high energy density and the silicon-carbon composite material providing structural stability, thereby resolving the contradiction between energy density and cycle performance
Solution Approach 2:
The patent employs composite materials strategy by combining silicon-oxygen-based material and silicon-carbon composite material in the same negative electrode. The silicon-carbon composite material acts as a structurally stable component that compensates for the volume expansion issues of silicon-based materials, while the silicon-oxygen-based material contributes high energy density, achieving both improved energy density and maintained cycle performance
2Use of energy by moving object
If silicon-oxygen-based material is used, then energy density is improved, but structural stability deteriorates
Solution Approach 1:
Different regions of the negative electrode are assigned different material compositions with specific local qualities. The first region contains silicon-oxygen-based material optimized for high energy density, while the second region contains silicon-carbon composite material optimized for structural stability. This local differentiation allows each region to excel at its intended function while the overall electrode benefits from both properties
3Stability of the object's composition
If silicon-carbon composite material is used, then structural stability is improved, but energy density deteriorates
Solution Approach 1:
The patent merges silicon-oxygen-based material and silicon-carbon composite material into a unified negative electrode structure. The silicon-carbon composite material provides the structural framework and stability, while the silicon-oxygen-based material is integrated to contribute high energy density. This merging allows the electrode to achieve both structural stability and high energy density simultaneously, overcoming the limitations of using either material alone
Data Source
AI summary
A secondary battery is provided. The secondary battery includes a negative electrode sheet comprising a negative electrode current collector and a negative electrode film layer. The film layer has a first surface adjacent to the current collector and a second surface opposite the first surface. The thickness of the film layer is denoted as H. A region extending from the first surface to a depth of 0.3H is defined as a first region, and a region extending from the second surface to a depth of 0.3H is defined as a second region. The first region includes a first active material, and the second region includes a second active material. The first active material comprises a siloxy material, and the second active material comprises a silicon-carbon composite. This structural configuration provides controlled material distribution across the electrode thickness, enabling improved performance, cycling stability, and mechanical integrity of the secondary battery.