Multilayer Polymer Solid Electrolyte for High Voltage Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current lithium secondary batteries face challenges in achieving stable operation in both high voltage regions at the positive electrode and low voltage regions at the negative electrode due to limitations in polymer electrolyte stability and interface resistance, particularly when using materials like LCO and Li metal or graphite electrodes.
Innovation Solution
A multi-layer polymer solid electrolyte structure comprising a first layer with an aliphatic dinitrile compound and lithium salt, and a second layer with an ionic liquid and lithium salt, which allows for stable ion conductivity and adhesion, enabling operation in high voltage regions up to 4.0V and low voltage regions down to 1.5V without decomposition or reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single polymer electrolyte is used, then the structure is simple and manufacturing is easy, but the electrolyte decomposes at high voltage positive electrodes or low voltage negative electrodes
Solution Approach 1:
The electrolyte is divided into multiple layers with different compositions: a first polymer electrolyte layer containing succinonitrile for high voltage stability and a second polymer electrolyte layer for low voltage stability. This segmentation allows each layer to specialize in stabilizing one electrode type, resolving the contradiction between manufacturing simplicity and electrolyte stability.
Solution Approach 2:
The invention uses composite polymer electrolyte materials combining different polymer matrices (PEO, PPO, PANI) with various lithium salts and additives. This composite approach enables the electrolyte to exhibit multiple properties simultaneously - high voltage stability from succinonitrile-containing layers and low voltage stability from other compositional elements.
2Device complexity
If a single polymer electrolyte is used, then the device complexity is low, but the interface resistance between electrode and electrolyte increases
Solution Approach 1:
Different regions of the electrolyte (first layer vs. second layer) have different local compositions optimized for specific electrodes. The first layer with succinonitrile provides stable interface with high voltage positive electrodes, while the second layer provides stable interface with low voltage negative electrodes, reducing interface resistance at each electrode-electrolyte boundary.
3Reliability
If organic liquid electrolyte is used, then ion conductivity is high, but safety risk of ignition and explosion increases
Solution Approach 1:
The invention replaces flammable organic liquid electrolytes with solid polymer electrolytes that contain short-chain nitriles like succinonitrile. These solid electrolyte components provide ionic conductivity while eliminating the fire and explosion hazards of liquid organic electrolytes, effectively removing the harmful safety risks.
4Object-affected harmful factors
If polymer electrolyte is used in high voltage region, then safety is improved, but the electrolyte is oxidized at the positive electrode surface
Solution Approach 1:
The first polymer electrolyte layer containing succinonitrile acts as an intermediary between the high voltage positive electrode and the rest of the electrolyte system. This intermediate layer is specifically designed to be stable at high voltages up to 4.3V, preventing direct oxidation reactions between the positive electrode and other electrolyte components.
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 multi-layer polymer electrolyte structure ensures stable performance in all solid-state batteries, enhancing voltage stability and ion conductivity, making it suitable for high-capacity and high-power applications, such as electric vehicles, by preventing electrolyte decomposition and reducing interface resistance.
Implementation Method 1
a first polymer electrolyte layer including an aliphatic dinitrile compound represented by the following formula 1, a lithium salt and a lithium ion conductive polymer, and a second polymer electrolyte layer including an ionic liquid, a lithium salt and a lithium ion conductive polymer
Implementation Method 2
there arises a problem that the polymer electrolyte is oxidized at the surface of the positive electrode in the high voltage region
Implementation Method 3
or is reduced/decomposed on the surface of the negative electrode in the low voltage region
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The present invention relates to a polymer electrolyte of a multi-layer structure and an all solid-state battery comprising the same, wherein the polymer electrolyte can exhibit an effect capable of stably operating in the high voltage positive electrode and in the low voltage negative electrode, when using the polymer solid electrolyte having a multi-layer structure, which includes the first polymer electrolyte layer and the second polymer electrolyte layer of the present invention, and the all solid-state battery containing it is applicable in the battery field of electric vehicle in which high capacity and high-power battery are used.