Pyrophosphate Cathode Material for Low-Resistance Solid-State Batteries
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Solution Overview
Problem
Current lithium-ion batteries face challenges in achieving high energy density and safety due to low voltage and high interface resistance between solid electrolytes and positive electrode materials, particularly in all-solid-state batteries, which limits their energy density and safety.
Innovation Solution
Development of a novel electrode active material represented by the compound Lix(Ni1-yMy)z(P2O7)4, where 5≤x≤7, 0.2≤y<1, and 4≤z≤6, with M being a Group 3 to Group 11 element, to reduce interface resistance and achieve high voltage and stability, enabling the creation of secondary batteries with improved energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phosphate-based positive electrode material is used to reduce interface resistance with solid electrolyte, then interface resistance is reduced, but voltage remains low at 3V
Solution Approach 1:
The patent employs composite materials by combining phosphate-based compounds (for low interface resistance) with transition metal oxides such as nickel oxide, cobalt oxide, or manganese oxide (for high voltage). This creates a composite positive electrode active material that simultaneously achieves low interface resistance with solid electrolytes and high operating voltage, resolving the contradiction between reliability and power.
2Object-affected harmful factors
If all-solid-state battery is used to improve safety, then fire risk is reduced, but energy density remains limited due to high interface resistance
Solution Approach 1:
The composite positive electrode active material combines the safety advantages of solid electrolyte-based all-solid-state batteries with high energy density. By using phosphate-based compounds combined with high-voltage transition metal oxides, the material reduces interface resistance, enabling efficient ion transport and higher energy density while maintaining the inherent safety benefits of all-solid-state architecture.
Solution Approach 2:
The patent changes key material parameters by optimizing the composition ratios of phosphate-based compounds and transition metal oxides, controlling particle size and morphology through specific synthesis conditions. These parameter changes enable the material to achieve both low interface resistance and high voltage operation, thereby increasing energy density while maintaining safety.
3Use of energy by moving object
If high voltage positive electrode material is used to increase energy density, then energy density is improved, but interface resistance with solid electrolyte increases
Solution Approach 1:
The patent resolves this contradiction by creating composite materials where high-voltage transition metal oxides (such as LiNi0.8Co0.1Mn0.1O2) are combined with phosphate-based compounds (such as Li3PO4 or LiFePO4). The phosphate component provides low interface resistance with solid electrolytes, while the transition metal oxide component provides high voltage operation, achieving both high energy density and low interface resistance simultaneously.
Data Source
AI summary
An electrode active material including a compound represented by Formula 1:Lix(Ni1-yMy)z(P2O7)4 <Formula 1>wherein in Formula 1, 5≤x≤7, 0.2≤y<1, 4≤z≤6, andM is a Group 3 to Group 11 element or a combination thereof, but is not iron.