Solid-State Battery Cathode Composite for Conductivity and Safety
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Solution Overview
Problem
Existing solid secondary batteries face challenges in achieving high energy density, improved safety due to flammability risks, and maintaining stability during charging and discharging.
Innovation Solution
A solid secondary battery design incorporating a cathode with an improved electronic conduction network, utilizing a composite cathode active material composed of M2S, an alkali metal salt, and a two-dimensional carbonaceous structure, which enhances both electronic and ionic conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If liquid electrolytes are used in lithium batteries, then energy density can be improved, but safety deteriorates due to overheating and flammability 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 energy storage functionality. This phase change eliminates flammability and overheating risks inherent in liquid electrolytes.
Solution Approach 2:
The patent employs a composite cathode active material consisting of M2S particles combined with conductive carbonaceous materials and binding agents. This composite structure simultaneously achieves high energy density from M2S and improved safety through the stable solid electrolyte interface.
2Reliability
If solid electrolytes are used instead of liquid electrolytes, then safety is improved, but initial efficiency and energy density characteristics worsen
Solution Approach 1:
The patent creates a composite cathode active material where M2S particles are combined with conductive carbonaceous materials. This composite structure provides both the safety benefits of solid electrolytes and the electrical conductivity needed for high initial efficiency and energy density.
Solution Approach 2:
The patent applies different materials with specific local functions: M2S provides high capacity, conductive carbonaceous materials provide electron transport pathways, and binding agents provide structural integrity. This localized functional assignment optimizes both safety and performance.
3Device complexity
If a simple cathode structure is used, then device complexity is reduced, but electronic conduction network and performance deteriorate
Solution Approach 1:
The patent uses a composite cathode active material where M2S particles are combined with conductive carbonaceous materials and binding agents. This composite approach enhances the electronic conduction network without requiring complex multi-layer cathode structures, maintaining relative simplicity while improving performance.
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 improved battery exhibits enhanced initial efficiency, energy density, and lifespan characteristics, while reducing the risk of overheating and flammability, thus providing a safer and more efficient energy storage solution.
Implementation Method 1
the cathode active material layer includes a composite cathode active material, the composite cathode active material includes a composite of M 2 S, an alkali metal salt, and a two dimensional carbonaceous structure... which enhances both electronic and ionic conductivity
Implementation Method 2
the composite includes a solid solution of M 2 S and the alkali metal salt... the solid secondary battery exhibits enhanced initial efficiency, energy density, and lifespan characteristics
Data Source
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AI summary
A solid secondary battery and a method of preparing the same are provided. The solid secondary battery includes a cathode layer, an anode layer, and a solid electrolyte layer between the cathode layer and the anode layer, wherein the cathode layer includes a cathode current collector and a cathode active material layer on at least one side 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 M2S, an alkali metal salt, and a two-dimensional carbonaceous structure, wherein M is an alkali metal, the alkali metal being Li or Na, the two-dimensional carbonaceous structure includes graphene, graphene oxide, reduced graphene oxide, or a combination thereof, and the composite includes a solid solution of the M2S and the alkali metal salt.