Silicon-Based Lithium Storage Material with Uniform Doping
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Solution Overview
Problem
Existing silicon-based lithium storage materials for lithium-ion batteries suffer from low first-cycle coulombic efficiency and poor cycle characteristics, and struggle to form materials with uniformly doped elements.
Innovation Solution
A silicon-based lithium storage material is developed, comprising a core with silicon and a doping element, coated with a graphitized carbon shell and a metal oxide shell. The core is prepared by heating a mixture of silicon, silicon oxide, and the doping element to a molten state and then cooling it rapidly. The carbon shell enhances conductivity, while the metal oxide shell improves safety and prevents lithium leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature and vacuum conditions are used to prepare silicon-based anode materials from silicon particles and silicon oxide, then the materials can be formed, but the first-time coulombic efficiency is low and cycle characteristics are poor
Solution Approach 1:
The patent changes the preparation parameters by using molten salt electrolysis at lower temperatures (below melting point of silicon) instead of high-temperature vacuum conditions. This parameter change enables uniform doping of elements like sulfur and phosphorus while improving both first-time coulombic efficiency and cycle characteristics of the silicon-based anode materials.
Solution Approach 2:
The patent creates composite silicon-based materials by uniformly doping multiple elements (sulfur, phosphorus, etc.) into the silicon structure during molten salt electrolysis. This composite approach improves cycle characteristics while maintaining high first-time coulombic efficiency, resolving the contradiction between reliability and manufacturing precision.
2Manufacturing precision
If conventional methods are used to prepare silicon-based anode materials, then materials can be obtained, but it is difficult to form materials with uniformly doped elements
Solution Approach 1:
The patent performs preliminary doping by incorporating doping elements into the silicon structure during the molten salt electrolysis process itself, before final material formation. This preliminary action ensures uniform distribution of dopants like sulfur and phosphorus throughout the silicon-based anode material, achieving high manufacturing precision without excessive preparation complexity.
Solution Approach 2:
The patent uses molten salt as an intermediary medium to facilitate uniform doping of elements into silicon. The molten salt enables controlled diffusion and uniform distribution of doping elements during electrolysis, achieving precise uniform doping while simplifying the overall preparation process compared to conventional multi-step methods.
3Use of energy by moving object
If silicon-based materials are used to increase battery capacity, then energy performance improves, but safety and first-cycle coulombic efficiency deteriorate
Solution Approach 1:
The patent changes the preparation parameters by using molten salt electrolysis to produce silicon-based anode materials with improved structural properties. This parameter change enables the material to maintain high battery capacity while simultaneously improving safety and first-cycle coulombic efficiency, resolving the contradiction between energy performance and reliability.
Solution Approach 2:
The patent creates composite silicon-based materials with uniformly distributed doping elements that improve both electrochemical performance and safety. The composite structure maintains high capacity while enhancing stability and first-cycle coulombic efficiency, thereby resolving the contradiction between energy usage and reliability.
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 silicon-based lithium storage material achieves higher capacity, improved first-cycle coulombic efficiency, and enhanced safety and stability, meeting market requirements for lithium-ion batteries.
Implementation Method 1
heating a mixture of silicon, silicon oxide, and the doping element to a molten state
Implementation Method 2
cooling it rapidly
Implementation Method 3
coated with a graphitized carbon shell and a metal oxide shell. The core is prepared by heating a mixture of silicon, silicon oxide, and the doping element to a molten state and then cooling it rapidly. The carbon shell enhances conductivity
Data Source
Figure 1
AI summary
The present invention provides a new silicon-based lithium storage material and a preparation method thereof. The silicon-based lithium storage material comprises: a first component and a second component, wherein the first component comprises Si with a valence of 0-4, with the proviso that 0≤CSi(1-4)/CSi(0)≤1, where CSi(1-4) is the molar amount of element silicon with a valence of 1-4, and CSi(0) is the molar amount of element silicon with a valence of 0; the second component comprises a doping element R, where the doping element R at least includes one of elements of main group I, II, and III, with the proviso that 0≤CR/CSi(0-4)≤1.5, where CR is the molar amount of the doping element R, and CSi(0-4) is the molar amount of element silicon with a valence of 0-4. The silicon-based lithium storage material improves its characteristics under a high-temperature storage condition as an active substance of a lithium ion secondary battery, and meanwhile improves the cycle characteristics and the initial charge-discharge coulombic efficiency of the battery.