Dual Solid Electrolyte Layout for High-Voltage All-Solid-State Cells
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing all-solid-state lithium-ion secondary batteries face challenges in increasing the charging voltage beyond 4.45 V due to the deterioration of solid electrolytes used as protective materials when exposed to higher voltages.
Innovation Solution
Employing a first solid electrolyte with a β-Li3AlF6 type structure or amorphous phase containing Li, Al, and F, and a second solid electrolyte with sulfide or oxide components, where the first electrolyte is interposed between the high-potential side electroconductive material and the second electrolyte, preventing direct contact and ensuring ion conduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solid electrolyte is used as a protective material to cover the positive electrode active material surface, then the interfacial resistance between the positive electrode active material and the solid electrolyte separator is reduced, but the solid electrolyte deteriorates when high charging voltage is applied
Solution Approach 1:
The patent employs a dual-layer solid electrolyte structure where a first solid electrolyte layer (high voltage resistant material such as LiNbO3, Li2SiO3, or Li2SiO2N) is positioned between the positive electrode active material and the second solid electrolyte layer (sulfide-based material). This intermediary arrangement allows the first layer to serve as a protective barrier that prevents direct contact between the positive electrode active material and the sulfide-based solid electrolyte, thereby reducing interfacial resistance while the first layer's inherent high voltage resistance protects it from deterioration at charging voltages exceeding 4.45 V.
2Use of energy by moving object
If the charging voltage is increased to improve energy density, then the energy density of the battery is improved, but the solid electrolyte as protective material deteriorates
Solution Approach 1:
The patent utilizes a composite solid electrolyte structure consisting of two different solid electrolyte materials with complementary properties. The first solid electrolyte layer is made of a material with high voltage resistance (such as lithium niobate, lithium silicate, or lithium siloxynitride) that remains stable at charging voltages above 4.45 V, while the second solid electrolyte layer is made of sulfide-based material that provides good ion conductivity. This composite structure enables the battery to operate at high charging voltages (5V or 6V) to achieve high energy density while the first layer protects against electrolyte deterioration.
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 arrangement enables all-solid-state lithium-ion secondary batteries to achieve charging voltages exceeding 5 V or 6 V while maintaining electrolyte integrity and ion conductivity.
Implementation Method 1
lithium ions are conducted between the two active materials via the solid electrolyte
Implementation Method 2
the solid electrolyte as the protective material deteriorates when a high charging voltage is applied. In the case of LiNbO3, which is a typical protective material, deterioration is accelerated when the charging voltage exceeds 4.45 V
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
[Problem] To provide an advantageous technique for further improving the charging voltage in an all-solid-state cell such as an all-solid-state lithium-ion secondary battery. [Solution] An arrangement structure of a solid electrolyte in an all-solid-state cell, including a first solid electrolyte that contains, as a main component, a crystalline phase containing Li, Al, and F and having a β-Li3AlF6 type structure or an amorphous phase containing Li, Al, and F within a range where x satisfies 2.0 or more and 5.0 or less in a composition formula LixAlF3+x, and including a second solid electrolyte that contains, as a main component, a sulfide or an oxide between a high-potential side electroconductive material and a low-potential side electroconductive material in an all-solid-state cell, and in which the first solid electrolyte is interposed between the high-potential side electroconductive material and the second solid electrolyte, and a contact portion between the high-potential side electroconductive material and the first solid electrolyte, and a contact portion between the first solid electrolyte and the second solid electrolyte are provided.