Layered Solid Electrolyte Sheet for Wide-Window All-Solid Batteries
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Solution Overview
Problem
Existing lithium secondary batteries with liquid electrolytes face issues such as ignition risk due to electrolyte leakage and decomposition, and all-solid state batteries suffer from inferior ion conductivity and narrow potential windows, affecting discharge capacity and lifespan.
Innovation Solution
A solid electrolyte sheet with distinct layers, each optimized for oxidation and reduction stability, using different binders and potentially including a base layer, to widen the potential window and improve battery stability and lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If liquid electrolytes are used in lithium secondary batteries, then high discharge voltage and output stability are achieved, but ignition risk due to electrolyte leakage and decomposition occurs
Solution Approach 1:
The patent changes the physical state parameter of the electrolyte from liquid to solid, specifically using a sulfide-based solid electrolyte. This parameter change eliminates the ignition risk associated with liquid electrolyte leakage and decomposition while maintaining high discharge voltage and output stability, thus resolving the technical contradiction between power performance and safety reliability
Solution Approach 2:
The patent employs composite material design by combining sulfide-based solid electrolyte with specific binders (PVDF-co-HFP, NBR, or SBR) to create a solid electrolyte sheet with optimized properties. This composite approach maintains the high power characteristics while improving the reliability and stability of the battery system
2Reliability
If all-solid state electrolytes are used to eliminate liquid electrolyte problems, then ignition risk is reduced, but ion conductivity and potential window range are insufficient
Solution Approach 1:
The patent optimizes the chemical composition parameters of the sulfide-based solid electrolyte to achieve a wide potential window (oxidation peak >2.8V or no oxidation peak, reduction peak between -1.0V and 1.0V). This parameter optimization improves ion conductivity and discharge capacity while maintaining the safety advantages of solid electrolytes, thus resolving the contradiction between reliability and power performance
3Reliability
If all-solid state batteries are developed to solve liquid electrolyte issues, then safety is improved, but lifespan characteristics are inferior
Solution Approach 1:
The patent optimizes the electrochemical stability parameters of the solid electrolyte by selecting sulfide-based materials with appropriate oxidation and reduction peak voltages. This parameter optimization ensures long-term electrochemical stability during charge-discharge cycles, thereby improving lifespan characteristics while maintaining the safety benefits of all-solid state design
Solution Approach 2:
The patent uses composite material construction with sulfide-based solid electrolyte and specific binders to enhance both safety and lifespan characteristics. The composite structure provides improved adhesion and structural stability, contributing to better durability and longer battery life while maintaining the inherent safety advantages of solid electrolytes
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A
AI summary
A solid electrolyte sheet 100 includes a first solid electrolyte layer 10 and a second solid electrolyte layer 20, respectively including a solid electrolyte. During LSV analysis according to linear sweep voltammetry, in the first solid electrolyte layer 10, a voltage at which an oxidation peak appears is more than 2.8 V (Li/Li+) or no oxidation peak appears, and in the second solid electrolyte layer 20, a voltage at which a reduction peak appears is -1.0 V (Li/Li+) or more and less than 1.0 V (Li/Li+). The composite solid electrolyte sheet including both the solid electrolyte layer with excellent oxidation stability and the solid electrolyte layer with excellent reduction stability has a wide range of a potential window, so that it can effectively suppress the deterioration of performance, such as discharge capacity and lifespan maintenance rate, during high-voltage charging of the battery.