Halogen-Modified LVP Cathode for Stable Sulfide Solid Interfaces
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Solution Overview
Problem
Conventional Li3V2(PO4)3 cathode materials for sulfide-based all-solid-state batteries suffer from side reactions and increased interfacial resistance at the solid-solid interface, leading to degradation and reduced performance.
Innovation Solution
A cathode material is developed by doping Li3V2(PO4)3 with a transition metal having an oxidation number of +5 or more, such as tungsten, and substituting the surface with a halogen element like chlorine, to enhance surface stability and energy density while suppressing side reactions with the solid electrolyte.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If Li3V2(PO4)3 is used as a cathode material in sulfide-based all-solid-state batteries, then high capacity and high voltage can be achieved, but side reactions occur at the solid-solid interface leading to degradation
Solution Approach 1:
The patent applies local quality by substituting only the surface layer of Li3V2(PO4)3 particles with Li3PO4, while maintaining the bulk LVP structure. This creates a core-shell structure where the inner core provides high capacity and voltage, while the outer shell provides surface stability and suppresses side reactions with the solid electrolyte.
Solution Approach 2:
The patent creates a composite material structure by combining Li3V2(PO4)3 with Li3PO4 to form a core-shell composite. The LVP core provides electrochemical performance while the Li3PO4 shell provides interface stability, achieving both high capacity and surface stability simultaneously.
2Power
If Li3V2(PO4)3 is used as a cathode material in sulfide-based all-solid-state batteries, then high capacity can be achieved, but interfacial resistance increases at the solid-solid interface
Solution Approach 1:
The patent modifies only the surface region of the cathode material with Li3PO4 substitution, preserving the bulk LVP structure responsible for high capacity while eliminating the harmful interfacial resistance through the stable Li3PO4 surface layer.
Solution Approach 2:
The Li3PO4 surface layer acts as an intermediary between the LVP cathode material and the sulfide-based solid electrolyte, mediating the interface to prevent direct harmful interactions while maintaining ionic conductivity for charge transfer.
3Ease of manufacture
If conventional LVP is used in sulfide-based all-solid-state batteries, then manufacturing simplicity is maintained, but side reactions with solid electrolyte occur
Solution Approach 1:
The patent performs preliminary action by pre-forming the Li3PO4 surface layer through controlled substitution during the synthesis process, so that when the battery is assembled, the harmful side reactions are already prevented by the pre-formed stable interface.
Solution Approach 2:
The patent changes the compositional parameter of the cathode material surface by substituting Li3PO4 for part of the LVP structure, transforming the surface chemistry to be compatible with sulfide-based solid electrolytes while maintaining the overall manufacturing process simplicity.
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 modified cathode material achieves improved charge and discharge capacities, energy density, and surface stability, equivalent to those of lithium ion batteries, while reducing side reactions and interfacial resistance, thus enabling its application in sulfide-based all-solid-state batteries.
Implementation Method 1
Li3V2(PO4)3 (LVP) is doped with a transition metal having an oxidation number of +5 or more
Implementation Method 2
the surface of the cathode material is substituted with a halogen element
Data Source
AI summary
A cathode material for sulfide-based all-solid-state batteries, in which Li3V2(PO4)3 (LVP) is doped with a transition metal having an oxidation number of +5 or more and the surface of the cathode material is substituted with a halogen element so as to have improved surface stability and energy density and to suppress side reactions with a solid electrolyte, a manufacturing method thereof, and an all-solid-state battery using the same.