Composite Electrolyte for Solid-State Battery Interface Stability
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Solution Overview
Problem
High-capacity all-solid Li ion secondary batteries face challenges due to the easy adhesion and subsequent separation of solid electrolytes and active materials when heated, leading to unsatisfactory charging and discharging cycles, primarily because of the expansion and contraction of active materials.
Innovation Solution
A composite electrolyte is developed using non-Li ion conductive inorganic solid particles with low Li ion conductivity and an organic electrolyte, where the weight ratio of the organic electrolyte to the inorganic compound is between 0.1% and 20%, forming a favorable interface and improving the battery's lifespan and high-temperature durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solid electrolyte is used in an all-solid Li ion secondary battery, then safety is improved by eliminating ignition risk, but the battery fails to achieve high capacity due to adhesion and separation issues between the solid electrolyte and active material during charging and discharging cycles
Solution Approach 1:
The patent uses a composite electrolyte comprising inorganic solid particles (such as Al2O3, SiO2, TiO2, or ZrO2) dispersed in an organic electrolyte. This composite structure combines the safety benefits of solid electrolytes with the ionic conductivity and flexibility of organic electrolytes, preventing adhesion and separation issues while maintaining high capacity performance
Solution Approach 2:
The patent specifies precise parameters for the composite electrolyte: inorganic solid particle content of 1-50 wt% (preferably 5-30 wt%), particle size of 0.1-10 μm (preferably 0.5-5 μm), and organic electrolyte composition ratios. These parameter optimizations ensure favorable interface formation between electrolyte and active material, reducing expansion/contraction influence while maintaining high ionic conductivity
2Productivity
If the active material expands and contracts during charging and discharging, then Li ion insertion and removal are enabled, but the active material separates from the solid electrolyte, reducing cycle performance
Solution Approach 1:
The inorganic solid particles act as intermediary elements between the organic electrolyte and active material. These particles form a favorable interface that accommodates the expansion and contraction of active material during cycling, preventing direct contact and adhesion issues between the organic electrolyte and active material while maintaining ionic conductivity pathways
Solution Approach 2:
The patent creates localized regions with inorganic solid particles distributed throughout the electrolyte, providing different functional zones: organic electrolyte regions for ionic conduction and inorganic particle regions for interface stabilization. This local quality differentiation allows the electrolyte to simultaneously provide flexibility for expansion/contraction and structural stability for interface maintenance
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 composite electrolyte enhances Li ion conductivity at the interface, reduces the impact of active material expansion and contraction, and improves the battery's cycle lifespan and thermal stability, allowing for more efficient charging and discharging.
Implementation Method 1
an inorganic compound having an Li ion conductivity at room temperature that is less than 1×10−10 S/cm and an organic electrolyte
Data Source
AI summary
The present invention is provided to reduce the influence of expansion and contraction of an active material, form a favorable interface between a solid electrolyte and an active material, and improve the high temperature durability and cycle lifespan of a battery. A secondary battery composite electrolyte includes an inorganic compound having an Li ion conductivity at 25° C. that is less than 1×10−10 S/cm and an organic electrolyte. The weight ratio between the organic electrolyte and the inorganic compound is 0.1% or more and 20% or less.