Lithium Transition Metal Oxynitride Anode for High Capacity Batteries
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Solution Overview
Problem
Existing negative electrode active materials for electrochemical devices have limited discharge capacity density due to restricted lithium ion occlusion and high reaction potentials, which hinder the production of high-capacity batteries and capacitors.
Innovation Solution
A lithium-containing transition metal oxynitride with a crystal structure belonging to the space group Fm3m is used, incorporating lithium, a transition metal element, oxygen, and nitrogen, allowing for increased lithium ion occlusion and reduced reaction potentials through optimized composition ratios and mechanochemical synthesis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional negative electrode active materials are used, then the device structure is simple and easy to manufacture, but the discharge capacity density is limited due to restricted lithium ion occlusion and high reaction potentials
Solution Approach 1:
The patent changes the crystal structure parameter from conventional space groups to space group Fm3m, and optimizes the composition parameters (y+z=2 to 4, y>0, z≥0.25, m+n=1) of the transition metal oxynitride LixTlmTllnNyOz. This parameter change enables the material to achieve high discharge capacity density (up to 3000 mAh/cc or more) while maintaining manufacturability through established synthesis methods
2Quantity of substance
If the lithium ion occlusion is increased to improve discharge capacity, then the energy storage capability improves, but the reaction potential increases beyond the usable range
Solution Approach 1:
The patent optimizes the compositional parameters of the transition metal oxynitride, specifically controlling the ratios of oxygen (y) and nitrogen (z) where y+z=2 to 4, y>0, z≥0.25. This composition optimization allows the material to occlude large amounts of lithium ions (x=0 to 3) while maintaining reaction potentials within the usable range (below 2 V versus Li+/Li), resolving the trade-off between capacity and potential
3Quantity of substance
If the crystal structure is optimized for high lithium ion occlusion, then the discharge capacity density increases, but the manufacturing precision requirements increase
Solution Approach 1:
The patent employs composite transition metal oxynitride materials with the formula LixTlmTllnNyOz, combining multiple transition metals (Tl and Tll from Group IVB, VB, VIB, or VIIB) in specific ratios. This composite approach achieves the desired crystal structure (space group Fm3m) and high discharge capacity density while allowing flexibility in composition that simplifies manufacturing control compared to single-metal compounds
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
This configuration enhances the discharge capacity density of electrochemical devices by increasing the amount of lithium ions that can be occluded and reducing reaction potentials within the usable range, leading to higher energy storage capabilities.
Implementation Method 1
increasing the amount of lithium ions that can be occluded
Implementation Method 2
electrochemical device having a high discharge capacity density
Data Source
AI summary
A negative electrode active material contains a lithium-containing transition metal oxynitride having a crystal structure belonging to the space group Fm3m. An electrochemical device includes a negative electrode which contains a negative electrode active material containing a lithium-containing transition metal oxynitride having a crystal structure belonging to the space group Fm3m; a positive electrode; and an electrolyte.