Lithium-Titanium Composite Oxide Electrode for High-Current Battery Performance
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Solution Overview
Problem
Nonaqueous electrolyte batteries using lithium-titanium composite oxides exhibit low lithium ion conductivity and poor large current characteristics due to high crystallite diameters and impurity phases, which impede the diffusion of lithium ions.
Innovation Solution
A lithium-titanium composite oxide with a crystallite diameter not larger than 6.9×10^2 Å, containing rutile and anatase TiO2, Li2TiO3, and lithium titanate with controlled peak intensities, is used as the negative electrode active material, enhancing ionic conductivity and large current discharge characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If lithium-titanium composite oxide with large crystallite diameter is used, then manufacturing is easier, but lithium ion conductivity decreases and large current characteristics worsen
Solution Approach 1:
The patent applies parameter changes by precisely controlling the crystallite diameter of lithium-titanium composite oxide to 700-800 Å and adjusting the intensity ratios of diffraction peaks (anatase TiO2 main peak intensity ratio 0.03-0.30, rutile TiO2 main peak intensity ratio 0.01-0.20, Li2TiO3 main peak intensity ratio 0.01-0.15). This optimization of physical and chemical parameters resolves the contradiction by achieving both ease of manufacture and improved large current characteristics through controlled crystallite size and phase composition.
2Ease of manufacture
If lithium-titanium composite oxide with large crystallite diameter is used, then manufacturing is easier, but lithium ion diffusion rate decreases
Solution Approach 1:
The patent resolves this contradiction by changing the crystallite diameter parameter to a specific range of 700-800 Å and controlling the phase composition parameters (intensity ratios of anatase TiO2, rutile TiO2, and Li2TiO3). This optimized parameter set maintains manufacturing feasibility while dramatically improving lithium ion diffusion rate, as evidenced by the enhanced large current discharge characteristics achieving 70% or more of initial capacity at 10C rate.
3Ease of manufacture
If lithium-titanium composite oxide contains impurity phases, then synthesis is simpler, but ionic conductivity decreases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the intensity ratios of diffraction peaks corresponding to impurity phases (anatase TiO2: 0.03-0.30, rutile TiO2: 0.01-0.20, Li2TiO3: 0.01-0.15) relative to spinel lithium titanate. This controlled presence of specific impurity phases at optimized levels resolves the contradiction by maintaining synthesis simplicity while achieving high ionic conductivity through balanced phase composition.
Solution Approach 2:
The patent employs composite materials by creating a multi-phase lithium-titanium composite oxide containing spinel lithium titanate as the main phase with controlled amounts of anatase TiO2, rutile TiO2, and Li2TiO3. This composite structure resolves the contradiction by combining multiple phases where each contributes specific properties, achieving both ease of manufacture and high ionic conductivity through synergistic phase interactions.
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 approach improves lithium ion diffusion rates and ionic conductivity, leading to enhanced large current characteristics and charge-discharge cycle performance in nonaqueous electrolyte batteries.
Implementation Method 1
lithium ions are migrated between the negative electrode and the positive electrode for charging and discharging the battery
Implementation Method 2
as determined by the X-ray diffractometry
Data Source
AI summary
A lithium-titanium composite oxide includes a crystallite diameter not larger than 6.9×102 Å, and includes a rutile type TiO2, an anatase type TiO2, Li2TiO3 and a lithium titanate having a spinel structure. The rutile type TiO2, the anatase type TiO2 and Li2TiO3 each has a main peak intensity not larger than 7 on the basis that a main peak intensity of the lithium titanate as determined by the X-ray diffractometry is set at 100.