Silicon Anode Material Crystallization Control
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Solution Overview
Problem
Existing silicon anode materials for lithium-ion batteries suffer from large volumetric expansion during lithium deintercalation, leading to pulverization, loss of electrical contact, and poor electrochemical performance, which limits their commercial application.
Innovation Solution
The anode material is designed with controlled crystallization instability (0.01≤F≤500) to reduce grain boundary surface energy, attenuate stress concentration, and improve structure stability, incorporating a silicon matrix with a carbon or non-carbon matrix to form a stable solid-state electrolyte membrane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If silicon anode material is used to increase energy density, then battery energy density is improved, but volumetric expansion occurs during lithium deintercalation causing pulverization and loss of electrical contact
Solution Approach 1:
The patent embeds silicon grains within a carbon matrix to form a composite structure. The carbon matrix acts as a protective container that accommodates the silicon grains during volume expansion, preventing pulverization while maintaining electrical contact. This nested structure allows the silicon to expand and contract without compromising the overall integrity of the anode material.
Solution Approach 2:
The patent creates a composite material consisting of silicon grains dispersed in a carbon matrix. The carbon component provides structural stability and electrical conductivity, while the silicon component provides high capacity. This composite structure combines the advantages of both materials to achieve high energy density while maintaining reliability during cycling.
2Reliability
If carbon coating is applied to improve conductivity and cycling stability, then electrochemical performance is enhanced, but the preparation process becomes complex
Solution Approach 1:
The patent combines the silicon grains and carbon matrix into a single integrated composite material system. Rather than applying carbon coating as a separate post-processing step, the carbon matrix is incorporated during material synthesis, creating a unified structure that simultaneously provides structural support, electrical conductivity, and mechanical stability in one fabrication process.
3Ease of manufacture
If simple carbon coating is used, then preparation process remains simple, but electrochemical performance does not improve sufficiently
Solution Approach 1:
The patent creates a composite material consisting of silicon grains dispersed in a carbon matrix. The carbon component provides structural stability and electrical conductivity, while the silicon component provides high capacity. This composite structure combines the advantages of both materials to achieve high energy density while maintaining reliability during cycling.
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 approach enhances electrochemical performance by reducing expansion, improving cycling stability, and maintaining electrical contact, resulting in high first coulombic efficiency and stable lithium intercalation.
Implementation Method 1
After the anode material is heated to 1000 °C under nitrogen protection and then subjected to temperature holding for 1 h, the average particle size of the silicon grains of the anode material measured at a temperature naturally cooled to 25 °C is M1 nm
Implementation Method 2
After the anode material is heated to 1000 °C under nitrogen protection and then subjected to temperature holding for 1 h, the average particle size of the silicon grains of the anode material measured at a temperature naturally cooled to 25 °C is M1 nm
Data Source
Figure 1~2
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Figure 4b~5a
AI summary
Provided are anode material and battery. The anode material includes a primary particle. The primary particle includes silicon grains. An average particle size of the silicon grains of the anode material measured at 25 °C is M0 nm. After the anode material is heated to 1000 °C under nitrogen protection and then subjected to temperature holding for 1 h, the average particle size of the silicon grains of the anode material measured at a temperature naturally cooled to 25 °C is M1 nm. A crystallization instability degree of the anode material is F, where F=(M1-M0)/M0, M1> M0, and 0.01≤F≤500. According to the anode material provided in the present disclosure, the problem of stress concentration caused by the primary particle including the silicon grains in a lithium deintercalation process may be attenuated, such that the structure stability of the anode material is improved, and an expansion rate of the material is reduced, thereby improving the electrochemical performance and cycling performance of the anode material.