Silicon Anode Material Composition for Cycle and Rate Performance
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Solution Overview
Problem
Existing silicon-based negative electrode active materials for secondary batteries face challenges in achieving both high cycle performance and high rate performance due to issues such as rapid silicon crystal grain expansion and ion diffusion barriers.
Innovation Solution
A silicon-based negative electrode active material containing a combination of K element and P element, which forms a silicate structure to buffer volume expansion and reduce ion diffusion barriers, thereby improving cycle and rate performance.
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 rapid expansion of silicon crystal grains
Solution Approach 1:
The patent changes the chemical composition parameters of the silicon-based material by incorporating specific amounts of K element (600-1500 ppm) and P element (50-200 ppm) to modify the crystal structure and buffer expansion, thereby improving cycle performance while maintaining energy density
Solution Approach 2:
The patent creates a composite silicon-based material system combining Si, K, and P elements where the synergistic interaction between these elements produces a material with both high energy density and improved cycle performance, resolving the contradiction between energy density and reliability
2Use of energy by moving object
If silicon-based materials are used as negative electrode active materials, then energy density is improved, but rate performance deteriorates due to ion diffusion barriers
Solution Approach 1:
The patent modifies the material composition by adding P element which specifically reduces ion diffusion barriers in the silicon crystal structure, enabling faster lithium ion transport while maintaining the high energy density characteristics of silicon-based materials
Solution Approach 2:
The composite silicon-based material with K and P elements creates a multi-functional system where P element addresses ion diffusion barriers for improved rate performance while K element manages volume expansion, allowing simultaneous achievement of high energy density and high rate performance
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 combination of K and P elements in the silicon-based negative electrode active material enhances both cycle performance and rate performance, achieving a synergistic effect beyond the sum of their individual contributions.
Implementation Method 1
K element may form a silicate structure with an oxysilicon-based material, while avoiding rapid expansion of silicon crystal grains and buffering volume expansion during cycling
Implementation Method 2
P element may effectively lower an ion diffusion barrier, increase a diffusion coefficient of lithium ions in a bulk phase, and contribute to improving rate performance of a battery
Data Source
AI summary
A silicon-based negative electrode active material and a method of preparing the same. The silicon-based negative electrode active material includes silicate containing alkaline earth metal elements, and the silicon-based negative electrode active material contains both K element and P element. The method includes providing raw materials containing Si element, O element, K element, P element, and alkaline earth metal element, using a vapor deposition method to heat the raw materials to form vapor and then cool the vapor to form a deposit, and pulverizing the deposit to obtain a pulverized product.