Solid Electrolyte Battery Negative Electrode Plasticizer SEI Formation
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Solution Overview
Problem
Solid electrolyte batteries face challenges with interfacial resistance and adhesion between the negative electrode active material layer and the separator, leading to reduced battery life and safety concerns due to the absence of a solid electrolyte interface (SEI) layer, which is typically formed with liquid electrolytes.
Innovation Solution
A solid electrolyte battery design where a plasticizer with a melting point of 30-130°C is used in the second negative electrode active material layer to soften the separator, reducing interfacial resistance and allowing the formation of an SEI layer, while maintaining mechanical properties and adhesion to the current collector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solid electrolyte is used without liquid electrolyte, then safety is improved and leakage is prevented, but interfacial resistance increases and battery life decreases
Solution Approach 1:
The patent applies different properties to different parts of the electrode structure. The first negative electrode active material layer uses a solid electrolyte for safety, while the second layer incorporates a liquid ion conductive material to reduce interfacial resistance. This local differentiation allows each layer to fulfill its specific function optimally.
Solution Approach 2:
The patent creates a composite electrode structure combining solid electrolyte and liquid ion conductive material in distinct layers. The solid electrolyte provides safety and structural integrity, while the liquid ion conductive material fills voids and reduces interfacial resistance, creating a synergistic composite system.
2Duration of action of stationary object
If a liquid ion conductive material is added to reduce interfacial resistance, then battery life is improved, but excessive liquid injection is required and manufacturing complexity increases
Solution Approach 1:
The liquid ion conductive material is incorporated into the second negative electrode active material layer during the electrode manufacturing process, before battery assembly. This preliminary incorporation eliminates the need for separate liquid injection steps after cell assembly, simplifying manufacturing while ensuring proper distribution.
Solution Approach 2:
The patent merges the function of liquid ion conductive material incorporation with the electrode manufacturing process itself. The liquid material is mixed into the slurry before coating, combining two operations (electrode fabrication and electrolyte introduction) into one integrated process.
3Object-affected harmful factors
If the separator is softened to reduce interfacial resistance, then ion conductivity is improved, but mechanical properties deteriorate and adhesion to current collector weakens
Solution Approach 1:
The patent applies softening effect locally to the separator region adjacent to the second negative electrode active material layer, while maintaining the mechanical integrity of the overall electrode structure. The liquid ion conductive material is confined to specific layers where softening is beneficial, leaving other regions mechanically robust.
Solution Approach 2:
The electrode structure uses composite materials where the solid electrolyte-based first layer provides mechanical strength, while the liquid-containing second layer provides softening and low interfacial resistance. This composite approach allows simultaneous achievement of mechanical integrity and electrical performance.
4Quantity of substance
If graphite-based negative electrode active material is used to improve energy density, then capacity is increased, but volume change during charge/discharge generates more voids and accelerates degradation
Solution Approach 1:
The patent incorporates liquid ion conductive material into the second negative electrode active material layer beforehand, which fills voids that will form during graphite expansion and contraction. This preliminary cushioning prevents void formation from accelerating degradation, accommodating graphite's volume changes while maintaining structural integrity.
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 solution effectively reduces interfacial resistance, enhances battery life by forming a protective SEI layer, and improves ion conductivity, thereby improving the overall performance and safety of the battery.
Implementation Method 1
a plasticizer having a melting point of 30-130°C is used in the second negative electrode active material layer to soften the separator
Implementation Method 2
a liquid material, such as an electrolyte or additive, may be absorbed preliminarily into a polymer-based separator
Data Source
AI summary
The present disclosure relates to a solid electrolyte battery including a negative electrode including: a negative electrode current collector; a first negative electrode active material layer formed on at least one surface of the negative electrode current collector and including a first negative electrode active material, a first solid electrolyte and a first electrolyte salt; and a second negative electrode active material layer formed on the first negative electrode active material layer and including a second negative electrode active material, a second solid electrolyte, a second electrolyte salt and a plasticizer having a melting point of 30-130° C., the solid electrolyte battery is activated at a temperature between the melting point of the plasticizer and 130° C., and a solid electrolyte interface (SEI) layer is formed on the surface of the second negative electrode active material.