NASICON Solid Electrolyte for Low-Temperature Lithium Battery Conductivity
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Solution Overview
Problem
Lithium ion batteries with high electromotive force face challenges due to unstable positive and negative electrodes, and the use of rare earth elements in solid electrolytes makes them expensive and difficult to produce, leading to reduced conductivity at low temperatures.
Innovation Solution
A solid electrolyte with a phosphate compound based on a NASICON type crystal structure, represented by the formula Li1+2xM1 2-x(Ca 1-y M2 y)(PO 4) 3, where M1 is Zr or Hf and M2 is Sr or Ba, is developed, which stabilizes the crystal structure and enhances lithium ion conductivity at temperatures lower than room temperature without using rare earth elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rare earth elements are used in solid electrolytes, then lithium ion conductivity is improved, but manufacturing cost increases and production difficulty increases
Solution Approach 1:
The patent replaces expensive rare earth elements with abundant and inexpensive elements such as magnesium (Mg), copper (Cu), and aluminum (Al) in the solid electrolyte composition. This substitution maintains the necessary lithium ion conductivity while dramatically reducing raw material costs and simplifying the supply chain, making the solid electrolyte more economically viable for commercial production
Solution Approach 2:
The patent optimizes the compositional parameters of the solid electrolyte by precisely controlling the ratios of Li, M1, M2, and (PO4) components in the formula Li1+2xM12-x(M2y)(PO4)3. By adjusting these parameters within specific ranges, the patent achieves high lithium ion conductivity without requiring rare earth elements, thus resolving the contradiction between performance and cost
2Reliability
If rare earth elements are used in solid electrolytes, then lithium ion conductivity is improved, but production complexity increases
Solution Approach 1:
The patent replaces rare earth elements with common elements like Mg, Cu, and Al that are readily available and easier to handle during production. This substitution simplifies the manufacturing process by eliminating the need for specialized handling procedures required for rare earth elements, thereby reducing production complexity while maintaining conductivity performance
3Use of energy by moving object
If electrodes are closely adhered to solid electrolyte, then energy density is improved, but chemical stability deteriorates
Solution Approach 1:
The patent develops a composite solid electrolyte material combining multiple elements (Li, M1, M2, PO4) in a specific composite structure. This composite approach creates a material that simultaneously achieves high lithium ion conductivity for energy density and enhanced chemical stability to resist reactions with high-potential electrodes, resolving the contradiction between these two requirements
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 solution provides a cost-effective solid electrolyte with high conductivity at low temperatures, enabling a chemically stable lithium battery with improved discharge rate performance and cycle life, suitable for use in battery packs and vehicles.
Implementation Method 1
a lithium lanthanum zirconate based compound capable of being easily obtained by a solid-state reaction in air and having high lithium ion conductivity has received attention
Data Source
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AI summary
According to one approach, there is provided a solid electrolyte including a phosphate compound represented by General Formula Li1+2xM12-x(Ca1-yM2y)x(PO4)3. In the General Formula above, M1 is at least one selected from the group consisting of Zr and Hf, M2 is at least one selected from the group consisting of Sr and Ba, x satisfies 0 < x < 2, y satisfies 0 < y ≤ 1.