Niobium Composite Oxide Anode for Rapid Lithium-Ion Charging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Nonaqueous electrolyte batteries, such as lithium-ion batteries, face challenges with rapid charge/discharge performance due to dendrite formation on carbon-based negative electrodes, leading to internal short circuits and low energy density when using titanium oxide as the active material, which has limited lithium adsorption sites and high electrode potential.
Innovation Solution
A niobium composite oxide (TiNb2O7) with a monoclinic crystal structure is developed, allowing for high lithium adsorption capacity and rapid diffusion, and the pH is adjusted between 7.4 and 12.5 to reduce solid acid site concentration, enhancing charge/discharge efficiency and energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If carbonaceous material is used as negative electrode active material, then capacity per weight is high (372 mAh/g), but dendrite precipitation occurs during rapid charge/discharge leading to internal short circuits and safety issues
Solution Approach 1:
The patent changes the electrode potential parameter by using titanium oxide with a higher potential (about 1.5 V vs. Li/Li+) compared to carbonaceous materials. This parameter change prevents dendrite formation while maintaining capacity through the redox reaction between Ti3+ and Ti4+ during lithium insertion and release
Solution Approach 2:
The patent uses titanium oxide as a composite oxide material that combines the benefits of high potential operation with stable crystal structure. The composite oxide enables both rapid charge/discharge capability and long-term reliability by preventing the dendrite issues associated with pure carbonaceous materials
2Reliability
If titanium oxide is used as negative electrode active material, then rapid charge/discharge performance is stable and life is extended, but energy density is low due to higher potential (1.5 V) and lower capacity per weight (175 mAh/g)
Solution Approach 1:
The patent changes the crystal structure parameter of titanium oxide from conventional forms to a specific monoclinic structure with space group C2/m or P12/ml. This structural parameter change increases the number of lithium adsorption sites and enables higher capacity while maintaining the stable high-potential operation characteristic
3Speed
If oxide material reacting at high potential (about 1.5 V vs Li/Li+) is used, then electrode potential is high enabling stable rapid charge/discharge, but surface film formation is difficult and electrolyte decomposition (side reaction) occurs easily
Solution Approach 1:
The patent changes the surface chemical environment parameter by controlling the pH to be between 7.4 and 12.5. This pH parameter change reduces solid acid site concentration on the oxide surface, which in turn suppresses electrolyte decomposition and side reactions while maintaining rapid charge/discharge capability
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 provides a high theoretical capacity of 387 mAh/g, stable charge/discharge performance, and improved energy density by optimizing lithium ion conduction paths and reducing side reactions with the electrolyte.
Implementation Method 1
The potential of the electrode using the titanium oxide is about 1.5 V based on metal lithium and is higher (nobler) than that of the negative electrode using the carbonaceous material. The potential of the titanium oxide is due to the redox reaction between Ti3+ and Ti4+ when lithium is electrochemically inserted and released.
Implementation Method 2
A niobium composite oxide (TiNb2O7) with a monoclinic crystal structure is developed, allowing for high lithium adsorption capacity and rapid diffusion
Implementation Method 3
the pH is adjusted between 7.4 and 12.5 to reduce solid acid site concentration, enhancing charge/discharge efficiency and energy density
Data Source
AI summary
An active material for a battery contains a niobium composite oxide represented by the formula: LixM(1-y)NbyNb2O(7+δ), where M represents at least one kind selected from Ti and Zr. X, y, and δ are numbers respectively satisfying the following: 0≤x≤6, 0≤y≤1, and −1≤δ≤1.