Silicon-Silicate Anode Material with Contact-Fused Li-Mg Interface
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Solution Overview
Problem
Existing silicon-based negative electrode materials for lithium-ion batteries face issues with battery lifetime characteristics, initial coulomb efficiency, and stability due to the reactivity of lithium silicate, which reacts with water and deteriorates during assembly, and Mg-doped SiO materials lead to decreased battery capacity and lifetime.
Innovation Solution
A method involving contact-fusion of Si with Li—Mg silicate materials at controlled temperatures and pressures to form a uniform interface, followed by vaporization and optional heat treatment, carbon coating, to create a stable and efficient negative electrode material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Li-doped SiO is used to improve initial coulomb efficiency, then initial efficiency is improved, but the material reacts with water and deteriorates during battery assembly
Solution Approach 1:
The patent uses a composite material system consisting of SiO2, Li2O, and MgO in specific ratios (SiO2: 70-90 wt%, Li2O: 5-20 wt%, MgO: 5-20 wt%) to create a material that combines the high initial coulomb efficiency of Li-doped SiO with the water stability of MgO, resolving the contradiction between efficiency improvement and reactivity reduction
Solution Approach 2:
MgO acts as an intermediary substance that reduces the reactivity of lithium silicate with water. The contact-fusion process creates a structure where MgO moderates the interaction between Li2O and water, allowing the system to maintain high initial efficiency while improving stability during battery assembly
2Reliability
If Mg-doped SiO is used to improve stability and initial coulomb efficiency, then stability is improved, but battery capacity decreases due to heavy Mg weight
Solution Approach 1:
The patent optimizes the MgO content parameter within a specific range (5-20 wt%) to achieve the desired balance between stability and capacity. By controlling the MgO concentration and using the contact-fusion process, the material achieves sufficient stability with minimal Mg content, thereby maintaining high battery capacity
Solution Approach 2:
The contact-fusion process creates local regions with optimized composition and structure where SiO2, Li2O, and MgO are uniformly distributed at the molecular level. This local optimization allows for minimal Mg doping while achieving maximum stability benefit, preserving overall battery capacity
3Reliability
If increasing Mg doping amount is used to improve initial coulomb efficiency, then initial efficiency is improved, but crystallization of Si phase progresses and battery lifetime characteristics decrease
Solution Approach 1:
The contact-fusion process is performed as a preliminary step before battery assembly, creating a uniformly distributed composite structure of SiO2, Li2O, and MgO that prevents subsequent crystallization of the Si phase. This preliminary action locks in the desired amorphous structure and composition, ensuring both high initial efficiency and long battery lifetime
Solution Approach 2:
The patent applies specific heating parameters (temperature and time control during contact-fusion) to achieve complete mixing and uniform distribution of components while preventing Si phase crystallization. By carefully controlling these parameters, the material achieves high initial coulomb efficiency without compromising battery lifetime characteristics
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 method produces a negative electrode material with high capacity, initial coulomb efficiency, and improved water resistance, resulting in enhanced battery performance and stability.
Implementation Method 1
heating the raw materials to form contact fusion state
Implementation Method 2
heating the raw materials to form contact fusion state
Implementation Method 3
vaporizing composite materials after the mixing step
Data Source
AI summary
A method of making negative electrode material having silicon and silicate includes the steps of providing raw materials for contact fusion, heating the raw materials to form materials with a contact-fusion state, mixing silicon and the materials after forming contact-fusion to form a composite material, and vaporizing the composite materials on the deposition zone after the mixing step. The heating step is performed at the temperatures between the lowest melting temperature of the materials with the contact-fusion state and 1400° C. The deposited composite materials can be optionally heat treated, pulverized, and/or coated with carbon. Also provided is a negative electrode material of silicon and silicate made from the steps described above. The negative electrode material of silicon and silicate can be an Li—Mg silicate having silicon powder dispersed therein, the Li—Mg silicate forming a uniform interface on surfaces of the silicon powder.