Halide Solid Electrolyte Cathode Material for High-Voltage Batteries
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Solution Overview
Problem
Existing battery technologies face inefficiencies in charge and discharge processes, particularly when the average discharge potential of the positive electrode active material exceeds the redox potential of Li metal by 3.7 V, leading to decreased charge and discharge efficiency.
Innovation Solution
A positive electrode material comprising a mixture of a positive electrode active material and a first solid electrolyte material, specifically a halide compound represented by Li a Me b Y c X 6, where a + mb + 3c = 6 and c > 0, with Me being certain metal elements or their mixtures, and X being Cl, Br, or I, forming a stable interface that enhances ionic electrical conductivity and reduces interface resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the average discharge potential of the positive electrode active material is increased beyond 3.7 V above the redox potential of Li metal, then the energy density and voltage of the battery is improved, but the charge and discharge efficiency decreases
Solution Approach 1:
A solid electrolyte layer comprising a halide compound (Li a Me b Y c X 6) is introduced as an intermediary between the positive electrode active material and the negative electrode. This intermediary layer facilitates efficient ion transport even at high discharge potentials, resolving the contradiction between achieving high voltage and maintaining charge-discharge efficiency.
Solution Approach 2:
The invention changes the chemical composition parameters of the electrolyte by using a specific halide compound formula (Li a Me b Y c X 6) with controlled stoichiometry (a + mb + 3c = 6, c > 0). This parameter optimization enables the electrolyte to maintain low interface resistance and high ionic conductivity across a wide voltage range, allowing efficient operation at discharge potentials exceeding 3.7 V.
2Reliability
If a sulfide solid electrolyte is used in the battery, then the ionic conductivity is improved, but the interface resistance with the positive electrode active material increases at high discharge potentials
Solution Approach 1:
The invention uses a composite halide compound (Li a Me b Y c X 6) combining lithium with multiple metal elements (Me) and halogen (X). This composite material structure provides both high ionic conductivity and low interface resistance with the positive electrode active material, overcoming the limitations of sulfide solid electrolytes at high discharge potentials.
Solution Approach 2:
The invention optimizes the compositional parameters of the solid electrolyte by controlling the ratios of Li, Me, Y, and X in the formula Li a Me b Y c X 6. This parameter optimization creates a material with balanced properties: high ionic conductivity for reliable performance and low interface resistance for efficient operation at high discharge potentials.
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
This configuration significantly improves the charge and discharge efficiency of batteries by increasing the rate of utilization of the active material and reducing interface resistance, maintaining high efficiency even at elevated discharge potentials.
Implementation Method 1
a first solid electrolyte material, specifically a halide compound represented by Li a Me b Y c X 6... forming a stable interface that enhances ionic electrical conductivity
Implementation Method 2
forming a stable interface that enhances ionic electrical conductivity and reduces interface resistance
Implementation Method 3
A positive electrode material for a battery... the charge and discharge efficiency of a battery can be improved
Data Source
Figure 1~3A
Figure 3B
Figure 4
AI summary
The positive electrode material according to an aspect of the present disclosure contains a positive electrode active material and a first solid electrolyte material. The first solid electrolyte material contains Li, M, and X; M at least contains either a metal element other than Li or a semimetal element; and X is at least one selected from the group consisting of CI, Br, and I.