Composite Sulfide Cathode for Safe High-Rate Solid Batteries
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing lithium batteries with liquid electrolytes are susceptible to fires and explosions due to short circuits, necessitating the development of solid secondary batteries with solid electrolytes for improved safety.
Innovation Solution
A solid secondary battery is designed with a cathode layer containing a composite cathode active material, which includes lithium sulfide (Li2S) or sodium sulfide (Na2S), an alkali metal salt, an inorganic electronically-conductive structure, and a two-dimensional carbonaceous structure or fibrous carbonaceous material, enhancing electron conduction and ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If liquid electrolytes are used in lithium batteries, then ionic conductivity is improved, but safety deteriorates due to fire and explosion risks
Solution Approach 1:
The patent changes the physical state parameter of the electrolyte from liquid to solid, fundamentally altering the safety characteristics while maintaining ionic conductivity through careful selection of solid electrolyte materials and their composite structures
Solution Approach 2:
The patent employs composite materials by combining solid electrolytes with conductive additives and active materials in specific ratios and configurations, creating a multi-component system that achieves both safety and high ionic conductivity
2Reliability
If solid electrolytes are used instead of liquid electrolytes, then safety is improved, but initial efficiency and rate capability deteriorate
Solution Approach 1:
The patent applies local quality by creating heterogeneous regions within the electrode structure, where conductive materials are locally concentrated to form efficient electron transport pathways, while solid electrolytes are positioned to ensure high ionic conductivity at critical interfaces
Solution Approach 2:
The patent utilizes two-dimensional carbonaceous structures and fibrous materials to create multi-dimensional conductive networks, transforming the traditional three-dimensional bulk structure into a hierarchical architecture with enhanced electron and ion transport pathways
3Object-affected harmful factors
If solid electrolytes are employed, then fire and explosion risks are reduced, but volumetric energy density deteriorates
Solution Approach 1:
The patent employs porous structures in the electrode and electrolyte design, creating void spaces that accommodate volume changes during cycling while maintaining high packing density of active materials, thereby improving volumetric energy density without compromising safety
Solution Approach 2:
The patent implements nested structures where one material is embedded within another, such as conductive particles within active material matrices, or core-shell structures, to maximize space utilization and energy density while maintaining safety characteristics
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 battery achieves improved initial efficiency, high-rate capability, and volumetric energy density, while reducing the risk of fires and explosions, thereby enhancing safety and performance.
Implementation Method 1
the inorganic electronically-conductive structure has an electronic conductivity of 10 -3
Implementation Method 2
a solid electrolyte layer provided between the cathode layer and the anode layer
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A solid secondary battery may include a cathode layer, an anode layer, and a solid electrolyte layer, wherein the cathode layer includes a cathode current collector and a cathode active material layer on one side or two sides of the cathode current collector, the cathode active material layer includes a composite cathode active material, the composite cathode active material includes a composite of i) M2S, ii) an alkali metal salt, iii) an inorganic electronically-conductive structure, and iv) a two-dimensional carbonaceous structure or a fibrous carbonaceous material having an aspect ratio of 2 or more, wherein M is an alkali metal, and the alkali metal is Li or Na, wherein the inorganic electronically-conductive structure has an electronic conductivity of 10-3 S/cm or more, the composite includes a solid solution of the M2S and the alkali metal salt, and the two-dimensional carbonaceous structure is graphene, graphene oxide, or a combination thereof.