Composite Oxide Negative Electrode for High Energy Density Batteries
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Solution Overview
Problem
Nonaqueous electrolyte batteries, particularly those using titanium oxide as a negative electrode, face challenges with low energy density and capacity due to limited lithium-absorbing sites and high electrode potential, making it difficult to achieve rapid and stable charge and discharge while maintaining safety.
Innovation Solution
A composite oxide with the general formula Lix(Nb1-yTay)2-zTi1+0.5zM0.5zO7 is developed, which has a monoclinic crystal structure allowing for increased lithium absorption and conductivity, enhancing energy density and charge-discharge performance by incorporating niobium, tantalum, and metal elements like Mo or W, thereby improving the electrode's potential and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If titanium oxide is used as negative electrode material, then rapid charge and discharge characteristics are improved, but energy density decreases
Solution Approach 1:
The patent changes the electrode potential parameter by using a composite oxide with lower potential than conventional titanium oxide. The composite oxide Lix(M1-aMg a)2-zTi1+0.5zM0.5zO7 achieves a lower operating potential, enabling higher capacity utilization and improved energy density while maintaining rapid charge-discharge characteristics.
Solution Approach 2:
The patent employs a composite oxide material combining multiple elements (Mg, Ti, Mo or W) in specific ratios. This composite structure provides both the rapid ion transport pathways needed for fast charging and additional lithium-absorbing sites to increase capacity, resolving the contradiction between speed and energy density.
2Productivity
If titanium oxide is used as negative electrode material, then rapid charge and discharge are enabled, but capacity per mass decreases
Solution Approach 1:
The patent changes the capacity parameter by introducing a composite oxide with lower electrode potential. The reduced potential allows the material to access additional lithium insertion sites, increasing theoretical capacity from ~165 mAh/g (anatase TiO2) to over 300 mAh/g for the composite oxide, while preserving fast ion transport.
Solution Approach 2:
The composite oxide structure combines MgO2, TiO3, and MO3 (M=Mo or W) in a monoclinic arrangement that provides both rapid ion pathways and increased lithium-absorbing capacity. The synergistic combination of elements delivers high capacity per mass alongside excellent rate performance.
3Quantity of substance
If electrode potential is lowered to improve energy density, then capacity increases, but safety and stability may be compromised
Solution Approach 1:
The patent uses a composite oxide with lower potential that intrinsically provides both high capacity and enhanced safety. The Mg-doped structure with monoclinic crystal system offers lower operating potential for higher energy density while the stable crystal framework prevents dendrite formation and maintains structural integrity during cycling, ensuring safety and stability.
Solution Approach 2:
The patent introduces localized Mg doping at specific sites in the crystal structure (substituting at M1 sites) to create regions of lower potential that enhance capacity. This localized modification maintains overall structural stability and safety while improving energy density through targeted compositional changes.
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 theoretical capacity of 300 mAh/g or more, significantly improving energy density and enabling excellent rapid charge and discharge characteristics with high cycle stability and reduced risk of internal short circuits.
Implementation Method 1
The potential of the electrode using the titanium oxide is due to the oxidation-reduction reaction between Ti3+ and Ti4+ when lithium is electrochemically absorbed and released
Implementation Method 2
it is necessary that electrons and lithium ions can migrate rapidly between a positive electrode and a negative electrode
Data Source
AI summary
A vehicle containing an nonaqueous electrolyte battery, the nonaqueous electrolyte battery including:a negative electrode containing a negative electrode active material;a positive electrode; anda nonaqueous electrolyte,where the negative electrode active material contains a composite oxide of formula:Lix(Nb1-yTay)2-zTi1+0.5zM0.5zO7,where 0≤x≤5, 0≤y≤1, and 0.4≤z≤1, and M is at least one metal element selected from Mo and W.