Ytterbium Solid Electrolyte Composition for 4 V Lithium Cathodes
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Solution Overview
Problem
There is a need for solid lithium ion conductors with high ionic conductivity and electrochemical oxidative stability up to 4 V vs. Li/Li+ to enable the use of cathode active materials with redox potentials of 4 V or more in all-solid state lithium batteries, as existing solid electrolytes fail to meet these requirements.
Innovation Solution
A solid material with the composition Li3−n*xYb1−xMxXy, where 0.05≤x≤0.95, 5.8≤y≤6.2, and M is a transition metal, exhibits favorable lithium ion conductivity and stability when used as a solid electrolyte, particularly when combined with cathode active materials and electron-conducting materials like carbon, surpassing the limitations of state-of-the-art solid electrolytes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional solid electrolytes are used, then the battery structure is simplified, but the electrochemical oxidative stability is insufficient for cathode materials with redox potential of 4 V or more
Solution Approach 1:
The patent modifies the chemical composition parameters of the solid electrolyte by incorporating specific ratios of Li, Yb, transition metal (Ti, Zr, Hf, V, Nb, or Ta), and halide/pseudohalide components according to formula (I). This compositional parameter optimization enables the electrolyte to achieve electrochemical oxidative stability sufficient for high-voltage cathode materials with redox potentials of 4 V or more, while maintaining appropriate ionic conductivity.
Solution Approach 2:
The patent creates a composite solid electrolyte material by combining multiple elements (lithium, ytterbium, transition metals, and halide/pseudohalide components) into a unified crystalline structure. This composite approach leverages the synergistic effects of different elements to achieve both high electrochemical oxidative stability and suitable lithium ion conductivity, enabling compatibility with high-voltage cathode materials.
2Use of energy by moving object
If the ionic conductivity is increased to improve battery performance, then the voltage capability is enhanced, but the electronic conductivity may increase causing safety issues
Solution Approach 1:
The patent optimizes the local chemical environment within the solid electrolyte structure by carefully selecting and ratioing specific elements at different positions in the crystal lattice. The transition metal component (Ti, Zr, Hf, V, Nb, or Ta) occupies specific lattice sites and creates localized regions that facilitate lithium ion transport while the overall composition maintains electronic insulation, achieving high ionic conductivity with negligible electronic conductivity.
Solution Approach 2:
The patent precisely controls the compositional parameters of the solid electrolyte, specifically the ratios of Li to (Yb + transition metal) and the halide/pseudohalide content, to optimize the balance between ionic and electronic conductivity. By adjusting these parameters within specific ranges defined in formula (I), the material achieves superior lithium ion conductivity while maintaining negligible electronic conductivity for safety.
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 proposed solid material achieves high lithium ion conductivity (0.1 mS/cm or more at 25°C) with negligible electronic conductivity, allowing for stable operation with cathode active materials of 4 V or more, thereby enhancing the performance and voltage capabilities of lithium batteries.
Implementation Method 1
a solid material having ionic conductivity for lithium ions
Implementation Method 2
with negligible electronic conductivity
Data Source
AI summary
Described are a solid material which has ionic conductivity for lithium ions, a composite comprising said solid material and a cathode active material, a process for preparing said solid material, a use of said solid material as a solid electrolyte for an electrochemical cell, a solid structure selected from the group consisting of a cathode, an anode and a separator for an electrochemical cell comprising the solid material, and an electrochemical cell comprising such solid structure.