SiOx Anode Composition With Partial Reduction for Higher First Efficiency
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Solution Overview
Problem
Current silicon monoxide (SiOx) anode materials for lithium ion batteries have low first coulombic efficiency due to irreversible reactions, and existing methods to improve this efficiency, such as using LiH or destroying the oxide framework, pose safety hazards or require complex equipment, while also failing to maintain the structural advantages of SiOx.
Innovation Solution
A silicon monoxide anode material comprising SiOy and a metal compound (M), where 0.2<y<0.9, is prepared through a redox reaction that adjusts the O/Si ratio and oxidizes the metal, maintaining the oxide framework and reducing oxygen content to enhance first coulombic efficiency, using common equipment and mild conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SiOx material is used as anode material, then capacity density and service life are improved, but first coulombic efficiency deteriorates (about 75%)
Solution Approach 1:
The patent changes the oxygen content parameter in SiOx material by controlling the reduction degree to obtain SiOy material with 0.2<y<0.5, thereby reducing irreversible capacity loss and improving first coulombic efficiency while maintaining the oxide framework structure for long service life
Solution Approach 2:
The patent creates a composite structure where reduced SiOy material is combined with residual oxide framework, achieving both high coulombic efficiency from reduced material and structural stability from oxide framework
2Loss of energy
If LiH is used to pre-intercalate lithium into SiOx material, then first coulombic efficiency is improved, but safety hazard increases due to flammability and explosiveness
Solution Approach 1:
The patent replaces dangerous LiH with safe metal powder (Mg, Al, or Ca) that can be handled under normal conditions, achieving the same reduction effect without the safety hazards of flammable and explosive LiH
Solution Approach 2:
The patent introduces metal powder as an intermediary reducing agent that mediates the reduction of SiOx to SiOy, providing a safe alternative to direct lithium insertion methods
3Loss of energy
If SiOx is thoroughly reduced by using large amount of magnesium, then first coulombic efficiency is improved, but oxide framework is destroyed and expansion control is lost
Solution Approach 1:
The patent applies partial reduction by controlling magnesium content (3-40 wt%) and reaction conditions to achieve only the necessary reduction degree (0.2<y<0.5), avoiding excessive reduction that would destroy the oxide framework while sufficient to improve coulombic efficiency
Solution Approach 2:
The patent precisely controls the reduction parameter (oxygen content y) to maintain it within 0.2<y<0.5 range, achieving optimal balance between coulombic efficiency improvement and framework preservation
4Manufacturing precision
If SiO vapor and metal vapor are reacted in gas phase, then anode material is prepared, but equipment complexity and energy requirements increase
Solution Approach 1:
The patent replaces complex gas-phase reaction equipment with simple solid-state reaction equipment, using metal powder reduction instead of vapor-phase reactions, thereby eliminating vacuum systems and high-temperature vaporization apparatus while achieving the same material transformation
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 resulting anode material achieves high first capacity, high first coulombic efficiency, excellent cycle performance, and reduced volume expansion, with the ability to regulate parameters for various capacities and efficiencies, while being safe and industrially viable.
Implementation Method 1
a redox reaction is performed on a raw material containing the SiOx material and the metal M, with the result that the O/Si ratio, i.e. x, of the SiOx material is adjusted to y
Data Source
AI summary
Disclosed are a lithium ion battery negative electrode material and a preparation method therefor. The negative electrode material comprises SiOy (0.2<y<0.9) and an M compound, wherein M is a metal. The method of the present application comprises: subjecting a raw material comprising a SiOx material and the metal M to a redox reaction, wherein the O/Si ratio, i.e. x, of the SiOx (0.5<x<1.5) material is adjusted to y (0.2<y<0.9), and at the same time, the metal M is oxidized to obtain the M compound.