Nitrogen-Doped Niobium Composite Oxide for Battery Conductivity
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Solution Overview
Problem
Nonaqueous electrolyte batteries face challenges with low energy density and poor conductivity, particularly when using titanium oxide as the negative electrode material, which limits quick charge-and-discharge performance and cycle life due to its insulating nature and low electron conductivity.
Innovation Solution
A niobium composite oxide with a general formula of Li x M (1-y) Nb y Nb 2 O (7+δ) is developed, where M can be Ti or Zr, and nitrogen atoms are doped in the range of 0.01% to 3.02% by mass to enhance conductivity, forming a stable crystal structure that allows for high lithium insertion and extraction, thereby improving energy density and charge-discharge performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If titanium oxide is used as the negative electrode active material, then quick charge-and-discharge can be stably performed with longer life, but the energy density is reduced due to higher potential and lower capacity per unit weight
Solution Approach 1:
The patent uses a composite oxide material (Li4Ti5O12-xNax) that combines the advantages of spinel structure (fast ion transport) with sodium doping to enhance capacity. This composite approach allows the material to maintain structural stability for long cycle life while achieving higher capacity through alien atom doping, thus resolving the contradiction between reliability and energy density.
2Quantity of substance
If a composite oxide (TiNb2O7) with high theoretical capacity is used, then charge-and-discharge capacity is improved, but electron conductivity is reduced due to insulating nature
Solution Approach 1:
The patent changes the chemical composition parameters by doping aluminum into the Li4Ti5O12 spinel structure, creating Li4-xAlxTi5-xO12. This parameter change modifies the electronic structure and conductivity of the material, allowing it to achieve both high capacity and improved electron conductivity, thus resolving the contradiction between quantity of substance and reliability.
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 composite oxide with nitrogen doping achieves a high energy density and excellent rate performance, enabling stable and repeated quick charge-and-discharge cycles while maintaining high capacity and large-current characteristics, addressing the limitations of titanium oxide batteries.
Implementation Method 1
nitrogen atoms are doped in the range of 0.01% to 3.02% by mass to enhance conductivity
Implementation Method 2
a stable crystal structure that allows for high lithium insertion and extraction
Implementation Method 3
The potential of titanium oxide is caused by an oxidation-reduction reaction between Ti 3+
Data Source
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AI summary
In general, according to one embodiment, there is provided an active material. The active material contains a a niobium composite oxide. The niobium composite oxide is represented by a general formula of LixM(1-y)NbyNb2O(7+δ). In the general formula, M is at least one selected from the group consisting of Ti and Zr, and x, y and δsatisfy 0 ≤ x ≤ 6, 0 ≤ y ≤ 1, and -1 ≤ δ ≤ 1, respectively. The niobium composite oxide contains nitrogen atoms in a content of 0.01% to 3.02% by mass.