Lithium Titanate-Coated Graphite Anodes for Fast-Charge Efficiency
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Solution Overview
Problem
Existing anode materials for lithium-ion batteries face challenges in achieving high energy density, fast charging performance, and low first-time efficiency, despite efforts to improve ion and electronic conductivity through doping and coating.
Innovation Solution
A method involving the preparation of nitrogen and fluorine-doped porous titanium dioxide, followed by lithium titanate coating on graphite, and subsequent carbonization to form nitrogen-fluorine co-doped lithium titanate/graphite composites, enhancing the structure and performance of the anode material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If amorphous carbon materials with large coating amount are selected to improve energy density and fast charging performance, then the isotropy and particle size are improved, but the market-oriented low-impedance raw materials have been basically screened and the impedance has not been significantly reduced
Solution Approach 1:
The patent uses composite materials by combining lithium titanate coating layer with graphite core, and further doping with nitrogen and fluorine elements. This composite structure reduces electronic impedance while maintaining fast charging performance, overcoming the limitation of conventional amorphous carbon coatings.
Solution Approach 2:
The patent changes the chemical composition parameters by doping nitrogen and fluorine elements into the lithium titanate coating layer. This parameter change modifies the electronic and ionic conductivity properties, significantly reducing impedance and improving power performance.
2Power
If doping is performed to increase ion diffusion rate and reduce electronic impedance, then the power performance is improved, but the first-time efficiency is low
Solution Approach 1:
The patent applies local quality by creating a lithium titanate coating layer with specific nitrogen and fluorine doping concentrations on the graphite surface. This localized doped structure optimizes both ion diffusion (improving power performance) and electronic conductivity (improving first-time efficiency) in different regions of the material.
3Reliability
If conventional doping materials such as amorphous carbon, nitrogen, boron and conductive agent are used, then the electronic conductivity is improved, but the ion transmission rate and power performance show insignificant improvement
Solution Approach 1:
The patent introduces lithium titanate as an intermediary material between the graphite core and the electrolyte. This intermediary layer facilitates both electron transport (maintaining electronic conductivity) and ion diffusion (improving ion transmission rate), resolving the trade-off between these two properties.
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 significantly improves the first-time efficiency and power performance of the anode material by reducing impedance and increasing ion and electron transmission rates, resulting in higher capacity and energy density.
Implementation Method 1
Dispersing tetrabutyl titanate in glycerol solvent to prepare 1～5 wt％solution and adding hexadecyl trimethyl ammonium bromide solution with the concentration of 12 g/L, adding tetramethylammonium hydroxide to adjust Ph to be 9-10, mixing uniformly; then adding 1 wt％ammonium fluoride solution, mixing uniformly and then transferring to a hydrothermal reactor, heating at 150-200℃ for 1～6 h
Implementation Method 2
heating at 150-200℃ for 1～6 h, the product was centrifuged, and washed with ethanol and water for 10 times, and dried in a vacuum drying oven at 60℃ for 12 h to obtain titanium/nitrogen/fluorine-doped porous titanium dioxide
Implementation Method 3
Preparing 1～10 wt％mass concentration of titanium/nitrogen/fluorine-doped porous titanium dioxide organic solution, and then adding 1～10 wt％mass concentration of lithium salt solution, mixing uniformly, then adding graphite, mixing uniformly, and spray drying to obtain porous lithium titanate-coated graphite composites
Implementation Method 4
heated at 400℃ for 2 h under the protection of argon, then heated to 800℃ for carbonization for 6 h to obtain nitrogen-fluorine co-doped lithium titanate/graphite composites
Data Source
AI summary
The invention discloses a preparation method of an anode material for lithium-ion batteries, comprising: dispersing tetrabutyl titanate in glycerol solvent and adding hexadecyl trimethyl ammonium bromide solution, adding tetramethylammonium hydroxide to adjust Ph; then adding ammonium fluoride solution, heating at 150-200° C. for 1˜6h, the product was centrifuged, washed, and dried in vacuum to obtain titanium/nitrogen/fluorine-doped porous titanium dioxide; preparing the titanium/nitrogen/fluorine-doped porous titanium dioxide organic solution, and then adding lithium salt solution, then adding graphite, mixing uniformly, and spray drying to obtain porous lithium titanate-coated graphite composites; taking porous lithium titanate-coated graphite composites and ammonium fluoride, placing them in a tube furnace, heating them under the protection of argon, and then heating them up to carbonization. The invention can improve the first-time efficiency of graphite composites and their power performance.