Monoclinic TiNb2O7 Core-Rutile Coating for Battery Electrodes
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Solution Overview
Problem
Nonaqueous electrolyte batteries face challenges with low energy density and rapid charge/discharge performance due to the limitations of titanium oxide-based electrodes, which suffer from low electron conductivity and capacity, leading to internal short circuits and reduced cycle durability.
Innovation Solution
The development of monoclinic niobium-titanium composite oxide particles with a rutile type niobium-titanium composite oxide coating, which improves electron conductivity and charge-discharge performance by enhancing Li diffusion and maintaining structural integrity during cycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If titanium oxide is used as negative electrode active material, then rapid charge/discharge performance is improved, but energy density decreases due to lower capacity per weight
Solution Approach 1:
The patent uses a composite structure of monoclinic TiNb2O7 core particles coated with rutile-type TiO2. The TiNb2O7 core provides high capacity (387 mAh/g theoretical) and rapid Li diffusion, while the rutile-type TiO2 coating enhances electron conductivity. This composite approach resolves the contradiction by combining materials with complementary properties to achieve both high energy density and rapid charge/discharge performance.
Solution Approach 2:
The patent changes the crystal structure parameter of TiNb2O7 from the conventional pseudobrookite structure to the monoclinic structure, which provides larger Li diffusion pathways and higher capacity. Additionally, the coating layer composition and thickness are optimized to balance electron conductivity and Li ion diffusion, resolving the contradiction between energy density and charge/discharge rate.
2Quantity of substance
If TiNb2O7 is used as active material, then capacity per weight increases, but electron conductivity decreases leading to increased overvoltage
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the core (monoclinic TiNb2O7) provides high capacity and the shell (rutile-type TiO2) provides high electron conductivity. Each region is optimized for its specific function, allowing the material to simultaneously achieve high capacity per weight and sufficient electron conductivity, reducing overvoltage during charge/discharge.
3Quantity of substance
If carbonaceous material is used in negative electrode, then capacity per weight is high, but dendrite precipitation occurs during rapid charge/discharge
Solution Approach 1:
The patent replaces the conventional carbonaceous material (graphite) with TiNb2O7, which has higher theoretical capacity (387 mAh/g vs. 372 mAh/g for graphite). The monoclinic structure of TiNb2O7 provides three-dimensional Li diffusion pathways that prevent dendrite formation during rapid charge/discharge, while maintaining high capacity. This substitution eliminates the harmful dendrite precipitation issue while preserving high capacity per weight.
4Productivity
If titanium oxide is used as negative electrode active material, then rapid charge/discharge is enabled, but potential is higher than carbonaceous material reducing energy density
Solution Approach 1:
The patent creates a composite structure combining TiNb2O7 with rutile-type TiO2 coating. The TiNb2O7 core enables rapid Li diffusion and high capacity, while the TiO2 coating provides excellent electron conductivity. This composite approach allows the negative electrode to operate at lower potentials (comparable to graphite) while maintaining rapid charge/discharge capability, thereby preserving high energy density.
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
This solution results in a nonaqueous electrolyte battery with improved input-output characteristics and cycle stability, maintaining high energy density and rapid charge/discharge capabilities while reducing the risk of internal short circuits.
Implementation Method 1
the electron conductivity of the monoclinic niobium-titanium composite oxide particles is improved
Implementation Method 2
enhancing Li diffusion
Implementation Method 3
The potential of titanium oxide is due to the redox reaction between Ti 3+
Data Source
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AI summary
According to one embodiment, there is provided an active material for a nonaqueous electrolyte battery excellent in input-output characteristics and cycle characteristics, a nonaqueous electrolyte battery including the active material, and a battery pack including the battery. The active material includes monoclinic niobium-titanium composite oxide particles. The monoclinic niobium-titanium composite oxide particles contain a rutile type oxide.