Lithium-Doped Silicon Oxide Anode Composition for High Initial Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current lithium-ion batteries with graphite anode materials have low theoretical specific capacity and high irreversible lithium consumption due to the formation of SEI films, limiting their initial Coulombic efficiency and cycle performance, while silicon oxide materials exhibit better cycle performance but low initial Coulombic efficiency.
Innovation Solution
A lithium-doped silicon oxide composite anode material with a specific phase composition ratio, including nano-silicon, lithium silicate, and a conductive carbon layer, optimized through a preparation method involving solid-phase mixing, heat treatment, and impurity removal to enhance initial Coulombic efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If silicon oxide material is used as anode material, then cycle performance is improved, but initial Coulombic efficiency deteriorates due to low initial Coulombic efficiency (20%-50% lithium consumption for SEI formation)
Solution Approach 1:
The patent changes the chemical composition parameters of the anode material by introducing lithium-doped silicon oxide with specific phase ratios (Li2SiO3 and Li2Si2O5). This parameter change transforms the material properties to achieve both good cycle performance and high initial Coulombic efficiency, resolving the contradiction between durability and efficiency.
Solution Approach 2:
The patent creates a composite anode material consisting of multiple phases (nano-silicon, lithium silicate including Li2SiO3 and Li2Si2O5, and conductive carbon layer) with specific composition ratios. This composite structure combines the advantages of different materials to simultaneously achieve good cycle stability and high initial Coulombic efficiency.
2Reliability
If graphite anode material is used, then initial Coulombic efficiency is maintained, but theoretical specific capacity deteriorates due to low theoretical specific capacity of 372 mAh/g
Solution Approach 1:
The patent changes the specific capacity parameter by replacing graphite with lithium-doped silicon oxide composite material, which has a theoretical specific capacity of 1300 mAh/g or higher. This parameter change directly addresses the capacity limitation while maintaining acceptable initial Coulombic efficiency through the specific phase composition.
Solution Approach 2:
The patent uses a composite material system (lithium-doped silicon oxide with specific phases) to achieve high specific capacity. The composite structure enables the material to deliver 1300 mAh/g or higher capacity while the controlled phase composition maintains initial Coulombic efficiency above 84%.
3Quantity of substance
If silicon anode material is used, then theoretical specific capacity is improved to 4200 mAh/g, but expansion ratio deteriorates due to expansion ratio up to 300%
Solution Approach 1:
The patent changes the material composition from pure silicon to lithium-doped silicon oxide with specific phases (Li2SiO3 and Li2Si2O5). This parameter change reduces the expansion ratio from 300% to 150% or lower while maintaining high specific capacity, resolving the contradiction between capacity and structural stability.
Solution Approach 2:
The patent creates a composite anode material containing nano-silicon, lithium silicate phases, and conductive carbon. This composite structure provides both high capacity and reduced expansion by distributing stress and preventing aggregate expansion, achieving expansion ratio of 150% or lower.
4Reliability
If pre-lithiated silicon oxide is used, then initial Coulombic efficiency is improved to some extent, but efficiency at 0.8V cutoff potential deteriorates due to low initial Coulombic efficiency ≤83.5%
Solution Approach 1:
The patent precisely controls the phase composition parameters of lithium silicate phases (Li2SiO3 and Li2Si2O5) in the anode material. This parameter optimization achieves initial Coulombic efficiency greater than 84% at 0.8V cutoff potential, improving upon conventional pre-lithiated silicon oxide materials.
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 lithium-doped silicon oxide composite anode material achieves high initial Coulombic efficiency and specific capacity, with improved reversible lithium intercalation properties, exceeding 84% efficiency at 0.8V and 1300 mAh/g capacity, suitable for high energy density lithium-ion batteries.
Implementation Method 1
During the lithiation process, SiO reacts with lithium to form inactive lithium silicates which decreases the irreversible lithium consumption to formation lithium silicates in the subsequently electrochemical measurement
Implementation Method 2
At the initial charge, 20% to 50% of lithium is consumed to form SEI films and irreversible substances
Implementation Method 3
carrying out heat treatment on the pre-lithiated precursor under a vacuum or non-oxidizing atmosphere
Data Source
AI summary
A lithium-doped silicon oxide composite anode material with high initial Coulombic efficiency and a preparation method are provided, which relates to the field of anode materials for lithium batteries. The material includes nano-silicon, lithium silicate and a conductive carbon layer. A diffraction peak intensity of Li2Si2O5(111) with 2θ being 24.7±0.2° in an XRD pattern of the lithium-doped silicon oxide composite anode material is I1, a diffraction peak intensity of Li2SiO3(111) with 2θ being 26.8±0.3° in the XRD pattern is I2, and I1/I2<0.25. The material provided in the present invention has a specific phase composition ratio, thereby achieving the effect of high initial Coulombic efficiency and high specific capacity.