Substituted β-LVO Anode Material for Low-Resistance Solid-State Batteries
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Solution Overview
Problem
Solid-state batteries using unsubstituted βII-Li3VO4 and γ-Li3VO4 as negative electrode active materials face issues with high initial reversible capacitance but low capacity retention rate at increased charge rates and high interface resistance with garnet-type solid electrolytes.
Innovation Solution
A negative electrode active material with a β-LVO-type crystal structure, where part of the V element is substituted with elements capable of forming a tetracoordinate structure, such as Si, Ge, P, or Ti, to enhance capacity retention and reduce interface resistance with garnet-type solid electrolytes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If unsubstituted βII-Li3VO4 or γ-Li3VO4 is used as negative electrode active material, then initial reversible capacitance is high, but interface resistance with garnet-type solid electrolyte is high
Solution Approach 1:
The patent applies parameter changes by substituting V elements in the Li3VO4 crystal structure with other elements (such as Ti, Nb, Ta, or Mo) to modify the material's properties. This substitution changes the crystal structure parameters and electronic properties, enabling the material to simultaneously achieve high initial reversible capacitance and low interface resistance with garnet-type solid electrolytes.
Solution Approach 2:
The patent creates composite materials by combining Li3VO4 with other metal elements through substitution. The resulting composite negative electrode active material (e.g., Li3-x-yMxNiyVO4 or Li3-x-yMxTiyVO4) integrates the advantages of different elements, achieving both high capacitance and low interface resistance that neither component could achieve alone.
2Quantity of substance
If γ-Li3VO4 is used as negative electrode active material, then initial reversible capacitance is high, but capacity retention rate is low when charge rate is increased
Solution Approach 1:
The patent changes the crystal structure parameters by using βII-Li3VO4 instead of γ-Li3VO4 and further substituting V elements with other metals. The βII-phase has a different crystal structure with better stability and ion diffusion pathways, which maintains capacity retention at high charge rates while preserving high initial reversible capacitance.
3Speed
If charge rate is increased, then charging speed is improved, but capacity retention rate becomes low
Solution Approach 1:
The patent modifies the negative electrode active material's crystal structure parameters and composition to enable faster lithium ion diffusion. The substituted βII-Li3VO4 structure provides more favorable diffusion pathways and lower activation energy, allowing the battery to maintain high capacity retention even at increased charge rates.
Data Source
AI summary
A negative electrode active material having a β-LVO-type crystal structure, in which a part of the V element of the β-LVO-type crystal structure is substituted with one or more elements capable of having a tetracoordinate structure, and preferably, the one or more elements capable of having the tetracoordinate structure are one or more elements selected from Zn, Al, Ga, Si, Ge, P, and Ti.