Niobium-Titanium Composite Oxide for Battery Capacity
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Solution Overview
Problem
Current nonaqueous electrolyte batteries, particularly those using titanium oxide as a negative electrode active material, face limitations in achieving higher capacity and energy density due to low electrical conductivity and strong lithium ion repulsion in their crystal structures.
Innovation Solution
The development of a niobium-titanium composite oxide with a specific crystal structure, represented by the general formula NbαTiβO7+γ, which includes a mixture of monoclinic titanium dioxide and Nb2TiO7 structures, enhancing lithium ion intercalation and stability, thereby improving capacity and energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If titanium oxide is used as negative electrode active material, then stable and rapid charge/discharge is achieved, but capacity is limited
Solution Approach 1:
The patent uses a composite material consisting of monoclinic titanium dioxide and Nb2TiO7 in a specific ratio (0.1-0.9 by mass). This composite structure combines the rapid charge/discharge capability of titanium oxide with the high capacity of niobium-containing compounds, resolving the contradiction between charge rate and capacity by integrating two materials with complementary properties.
Solution Approach 2:
The patent optimizes the mass ratio parameter of the composite materials (monoclinic titanium dioxide to Nb2TiO7) to achieve the best balance between charge/discharge rate and capacity. By adjusting this compositional parameter within the specified range, the battery performance is optimized to simultaneously improve both charge rate and capacity.
2Quantity of substance
If conventional niobium-titanium composite oxide is used, then capacity is improved, but electrical conductivity remains low
Solution Approach 1:
The patent changes the crystal structure parameter by specifically synthesizing monoclinic titanium dioxide and controlling its ratio with Nb2TiO7. This structural parameter change improves electrical conductivity while maintaining high capacity, resolving the contradiction between capacity and conductivity.
Solution Approach 2:
The composite of monoclinic titanium dioxide and Nb2TiO7 creates a material system where the two components work synergistically. The monoclinic structure provides good conductivity while Nb2TiO7 contributes to high capacity, together resolving the contradiction between conductivity and capacity.
3Speed
If monoclinic titanium dioxide is used, then rapid charge/discharge is achieved, but energy density is insufficient
Solution Approach 1:
The patent creates a composite material system where monoclinic titanium dioxide (providing rapid charge/discharge speed) is combined with Nb2TiO7 (providing high energy density). This composite approach allows the battery to simultaneously achieve fast charging capability and high energy density by leveraging the strengths of both materials.
Solution Approach 2:
The patent optimizes the compositional ratio parameter between monoclinic titanium dioxide and Nb2TiO7 to achieve the optimal balance between charge/discharge speed and energy density. By adjusting this parameter, the battery performance is tuned to simultaneously improve both speed and 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
The niobium-titanium composite oxide achieves higher effective capacity and energy density by allowing more stable lithium ion insertion and maintaining electrical neutrality, outperforming conventional niobium-titanium composite oxides and monoclinic titanium dioxide.
Implementation Method 1
enhancing lithium ion intercalation and stability, thereby improving capacity and energy density
Data Source
AI summary
According to one embodiment, there are provided an active material for a battery having a high effective capacity, a nonaqueous electrolyte battery, and a battery pack. The active material contains a niobium-titanium composite oxide. When the active material is subjected to powder X-ray diffraction (XRD) using a Cu-Kα ray source, a peak appears in a range of 2θ=5°±0.5° in the diffraction pattern.