Niobium-Titanium Composite Electrode for Battery Stability
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Solution Overview
Problem
Secondary batteries with carbon-based negative electrodes face issues such as rapid charge/discharge limitations, heat generation, and short circuit risks due to lithium dendrite formation, while titanium-based electrodes offer stability but have low energy density and capacity due to their noble nature and limited lithium-insertion sites.
Innovation Solution
A niobium-titanium composite oxide electrode with specific particle size and crystallite diameter ranges (90 nm to 200 nm) and surface roughness is used, enhancing the battery's ability to absorb volume changes during charging and discharging, thereby improving life and charge/discharge performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a carbon-based negative electrode is used, then high capacity per weight is achieved, but lithium dendrite precipitation occurs during rapid charge/discharge
Solution Approach 1:
The invention changes the material parameter from carbon-based to niobium-titanium composite oxide, which has a different electrochemical potential and crystal structure that prevents dendrite formation while maintaining rapid charge/discharge capability
Solution Approach 2:
The invention uses a composite material consisting of niobium oxide and titanium oxide in specific ratios (0.2-0.8 mol fraction of Nb2O5), combining the advantages of both materials to achieve both safety and performance
2Reliability
If titanium oxide is used in the negative electrode, then rapid charge/discharge stability is improved, but energy density decreases
Solution Approach 1:
The invention optimizes the compositional parameters by controlling the mol fraction of Nb2O5 between 0.2-0.8, which adjusts the electrochemical properties to achieve both stability and higher energy density compared to pure titanium oxide
Solution Approach 2:
The composite of niobium oxide and titanium oxide combines the stability of titanium oxide with the higher capacity contributions from niobium oxide, achieving synergistic effects that improve energy density while maintaining stability
3Quantity of substance
If TiNb2O7 is used as electrode material, then theoretical capacity exceeds 380 mAh/g, but practical capacity is only about 260 mAh/g with short charge/discharge life
Solution Approach 1:
The invention changes the stoichiometric parameters by using specific mol fractions of Nb2O5 (0.2-0.8) rather than the fixed TiNb2O7 composition, optimizing the crystal structure and lithium insertion sites to improve both capacity and cycle life
Solution Approach 2:
The invention creates local structural quality variations through the composite oxide structure, providing multiple types of lithium insertion sites with different properties, which improves both capacity utilization and structural stability during cycling
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 electrode achieves long life and high charge/discharge capacity, maintaining crystal structure integrity and reducing side reactions, leading to improved energy density and stability during rapid charging and discharging.
Implementation Method 1
the theoretical capacity of titanium dioxide (anatase structure) is about 165 mAh/g, and the theoretical capacity of spinel type lithium-titanium composite oxides such as Li 4 Ti 5 O 12 is about 180 mAh/g
Implementation Method 2
enhancing the battery's ability to absorb volume changes during charging and discharging
Data Source
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AI summary
According to one approach, an electrode is provided. The electrode includes an active material-containing layer which contains an active material. The active material includes a plurality of primary particles containing a niobium-titanium composite oxide. The average crystallite diameter of the plurality of primary particles is 90 nm or more. The average particle size (D50) of the plurality of primary particles is in a range of 0.1 µm to 5 µm. The average value (FUave) of the roughness shape coefficient (FU) according to Formula (1) below is less than 0.70 in 100 primary particles among the plurality of primary particles. [Formula 1] FU=ffc=4πaℓ2