Composite Cathode Structure for Solid-State Battery Rate and Density
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Solution Overview
Problem
Existing lithium batteries with liquid electrolytes are prone to short circuits, overheating, and potential fires or explosions, necessitating the development of safer alternatives like solid secondary batteries with solid electrolytes.
Innovation Solution
A solid secondary battery design featuring a cathode with an improved electronic-conductive network, comprising a composite cathode active material made of M2S, an alkali metal salt, and an inorganic electronic-conductive structure, which enhances initial efficiency, high-rate characteristics, and volumetric energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a liquid electrolyte is used in lithium batteries, then the battery can operate with conventional electrode materials, but the battery is prone to short circuits, overheating, and potential fires or explosions
Solution Approach 1:
The patent changes the physical state parameter of the electrolyte from liquid to solid, fundamentally altering the safety characteristics of the battery system. This phase change eliminates the flammability and leakage issues inherent in liquid electrolytes while maintaining ionic conductivity through carefully selected solid electrolyte materials.
Solution Approach 2:
The patent employs composite material structures combining solid electrolytes with electrode materials to achieve both safety and performance. The composite approach allows integration of multiple functional properties including ionic conductivity, electronic insulation, and structural stability within a unified battery architecture.
2Reliability
If a solid electrolyte is used instead of liquid electrolyte, then the possibility of fires or explosions is reduced, but the electronic conductivity and initial efficiency may be compromised
Solution Approach 1:
The patent applies local quality optimization by designing specific cathode structures with enhanced electronic conductivity in critical regions. The cathode is engineered with conductive networks and optimized material compositions at specific locations to ensure sufficient electron transport pathways while maintaining the overall solid electrolyte safety benefits.
Solution Approach 2:
The patent uses composite material strategies in the cathode structure, combining materials with complementary properties to achieve both electronic conductivity and compatibility with solid electrolytes. This includes using conductive additives, optimized active material compositions, and hierarchical structures that facilitate electron transport without compromising safety.
3Power
If the cathode structure is optimized for high electronic conductivity, then initial efficiency and high-rate characteristics improve, but the volumetric energy density may be reduced
Solution Approach 1:
The patent addresses this contradiction by transitioning from two-dimensional surface optimization to three-dimensional volumetric optimization of the cathode structure. This includes designing 3D conductive networks, hierarchical pore structures, and multi-scale architectures that provide efficient electron transport pathways throughout the volume while maximizing active material content and energy density.
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 cathode design reduces internal resistance, increases specific capacity, and enhances the lifespan characteristics of the solid secondary battery, thereby addressing safety concerns and improving performance.
Implementation Method 1
the inorganic electronic-conductive structure has an electronic conductivity of 1×10−3 siemens per centimeter (S/cm) or more
Implementation Method 2
a solid electrolyte layer provided between the cathode layer and the anode layer
Data Source
AI summary
A solid secondary battery and a method of manufacturing the same are provided. The solid secondary battery includes a cathode layer, an anode layer, a solid electrolyte layer provided between the cathode layer and the anode layer, wherein the cathode layer includes a cathode current collector and a cathode active material layer provided on one surface or two surfaces of the cathode current collector. The cathode active material layer includes a composite cathode active material, and the composite cathode active material includes a composite of M2S, an alkali metal salt, and an inorganic electronic-conductive structure, wherein M is an alkali metal, and the alkali metal is Li or Na. The inorganic electronic-conductive structure has an electronic conductivity of 11×10−3 S/cm or more, and the composite includes a solid solution of the M2S and the alkali metal salt.