Titanium-Niobium-Tungsten Oxide Anode for High-Rate Li-Ion Batteries
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Solution Overview
Problem
Current lithium-ion secondary batteries face limitations in energy density and rapid charge-discharge performance, particularly with carbon-based negative electrodes prone to lithium dendrite formation and lower theoretical capacity compared to metal composite oxides like Li4Ti5O12, which compromises battery life and energy efficiency.
Innovation Solution
Development of a titanium-niobium-tungsten composite oxide with a monoclinic and orthorhombic crystal structure, represented by the formula Li a Ti b Nb 2 W c O 2b+3c+5+δ, that enhances lithium insertion capacity and volume expansion, combined with additive elements to improve conductivity and structural stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a carbon-based negative electrode is used, then the energy density is improved, but lithium dendrites precipitate causing safety issues and reduced reliability
Solution Approach 1:
The patent changes the operating potential parameter of the negative electrode from the conventional carbon-based low potential to a higher potential range (0.5-1.8V vs Li/Li+), specifically using Li4Ti5O12 which operates at 1.55V. This parameter change prevents lithium dendrite formation while maintaining high capacity through the combined use of multiple active materials with different electrochemical characteristics
Solution Approach 2:
The patent employs composite materials by combining Li4Ti5O12 with other active materials such as titanium oxide, niobium oxide, and tungsten oxide in the negative electrode. This composite structure integrates the high safety and structural stability of Li4Ti5O12 with the high capacity of other materials, achieving both safety and energy density requirements
2Reliability
If Li4Ti5O12 is used in the negative electrode, then battery reliability is improved, but the theoretical capacity decreases to 175 mAh/g
Solution Approach 1:
The patent merges Li4Ti5O12 with other active materials including titanium oxide, niobium oxide, and tungsten oxide in specific weight ratios. This combination allows the battery to inherit the structural stability and safety of Li4Ti5O12 while gaining additional capacity from the other materials, achieving a theoretical capacity exceeding 175 mAh/g
Solution Approach 2:
The patent applies local quality by assigning different functional roles to different materials in the composite: Li4Ti5O12 provides structural stability and safety at the core, while other active materials contribute additional capacity. The specific weight ratios are optimized to balance these local functions for overall performance enhancement
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 composite oxide achieves a higher capacity per mass, improved rate performance, and extended battery life by optimizing lithium insertion and structural integrity, addressing the energy density and stability issues of existing battery materials.
Implementation Method 1
exhibiting a high capacity while having an operating potential near 1 V (vs. Li/Li+) and a flat potential profile during lithium insertion
Implementation Method 2
secondary batteries such as a lithium-ion secondary battery and a nonaqueous electrolyte secondary battery
Data Source
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AI summary
An active material includes a composite oxide represented by the general formula LiaTibNb2WcO2b+3c+5+δ and satisfying 0 ≤ a ≤ b + 3c + 4, 0 < b < 2, 0 < c < 2, 1.9b + 2.85c + 4.75 ≤ δ ≤ 2.1b + 3.15c + 5.25. A crystal structure of the composite oxide is at least one of a monoclinic structure and an orthorhombic structure.