High-Entropy DRX Cathodes With Reduced SRO for Li-Ion Transport
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing high entropy disordered rocksalt (DRX) cathodes suffer from reduced capacity and rate performance due to the presence of short-range order (SRO), which limits the amount of percolating lithium and hinders efficient lithium transport.
Innovation Solution
A high entropy mixture of transition metal species is used to synthesize DRX materials, reducing short-range order and enhancing lithium percolation by increasing the number of transition metal species, thereby mitigating SRO and improving capacity and rate performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a DRX cathode is designed with transition metal species, then redox activity and capacity are improved, but short-range order (SRO) forms which reduces percolating lithium and hinders lithium transport
Solution Approach 1:
The patent changes the compositional parameters by incorporating five or more different transition metal species in the TM[n] sublattice, creating a high-entropy mixture that disrupts SRO formation. This parameter change (increasing compositional complexity) transforms the system from one that forms SRO to one that maintains a more random cation distribution, thereby preserving percolating lithium pathways while maintaining high capacity through multiple redox-active species.
Solution Approach 2:
The patent creates a composite material system by combining five or more different transition metal species (such as Mn, Ti, Nb, Co, Cr) into a single DRX cathode material with formula Li1+xTM[n]1−xO2−yFy. This composite approach allows the material to benefit from the redox activity of multiple metal species while the high-entropy composition prevents SRO formation, simultaneously achieving high capacity and efficient lithium transport.
2Speed
If the number of transition metal species is increased to reduce SRO, then lithium percolation and rate performance are improved, but device complexity increases
Solution Approach 1:
The patent changes the compositional parameter by specifying exactly five or more transition metal species, which is sufficient to achieve the high-entropy effect and reduce SRO without unnecessarily increasing complexity. This optimized parameter selection balances the need for reduced SRO (improved rate performance) with practical compositional complexity, avoiding the need for even more metal species.
Solution Approach 2:
The patent achieves a homogeneous distribution of multiple transition metal species throughout the DRX structure, where the high-entropy mixture of five or more metals creates a uniform, random cation distribution that prevents SRO formation. This homogeneity in the high-entropy state ensures consistent lithium percolation pathways and rate performance throughout the material, while the uniformity actually simplifies the overall structure compared to materials with localized SRO regions.
3Stability of the object's composition
If SRO is present in DRX materials, then local cation ordering occurs, but the amount of percolating lithium is reduced and capacity is limited
Solution Approach 1:
The patent inverts the conventional approach by not seeking to maintain or enhance local cation ordering (SRO), but rather by deliberately designing a high-entropy composition that suppresses SRO formation. This inversion strategy transforms the problem: instead of accepting SRO as an inevitable feature of DRX materials with limited metal species, the patent uses five or more transition metal species to create a random cation distribution that maximizes percolating lithium while still providing stable composition through the high-entropy effect.
Data Source
AI summary
A class of compositions that are inclusive of a lithium metal oxide or oxyfluoride compound having a general formula: LiTM[n]OF where TM[n] represents a number of transition metal species inclusive of transitional metal species differentiated by charge or d0 electron shell conformation, with [n] being at least 4 of said transitional metal species, and wherein said lithium metal oxide or oxyfluoride has a cation-disordered rocksalt (DRX) structure and a mitigated SRO via a high entropy DRX design strategy. Also featured is a method of synthesizing the high entropy DRX lithium metal oxide or oxyfluoride compounds, as well as usage of the same in Li-ion batteries, with particular utility in cathodes of such Li-ion batteries.