High-Voltage Electrolyte Composition for Stable Cathode Protection
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Solution Overview
Problem
High-voltage electrochemical devices face issues with increased oxidation activity of positive electrode materials, leading to electrolyte decomposition and decreased stability, which affects battery capacity and internal resistance.
Innovation Solution
An electrolyte composition comprising a dinitrile compound, a trinitrile compound, and propyl propionate, with specific weight ratios, forms a protective film that inhibits solvent decomposition and reduces DC internal resistance, enhancing the stability and performance of electrochemical devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-voltage electrochemical devices are used to increase capacity density, then energy storage capacity is improved, but oxidation activity of positive electrode material increases leading to electrolyte decomposition and decreased stability
Solution Approach 1:
The patent introduces a protective film as an intermediary layer between the positive electrode material and the electrolyte. This film, formed by specific compounds on the electrode surface, mediates the interaction by preventing direct contact and harmful oxidation reactions while allowing ionic transport, thus resolving the contradiction between high voltage operation and electrolyte stability
Solution Approach 2:
The patent changes the chemical composition parameters of the electrolyte by introducing specific compounds that form protective films. By adjusting the chemical properties and composition of the electrolyte system, it enables stable operation at high voltages (4.4V and above) without causing decomposition, thus resolving the contradiction between voltage/capacity and stability
2Reliability
If protective film is formed on cathode surface to inhibit solvent decomposition, then electrolyte stability is improved, but protective film itself decomposes at high potential reducing long-term effectiveness
Solution Approach 1:
The patent employs a composite electrolyte system containing multiple compounds (dinitrile compound, trinitrile compound, and propyl propionate) that work synergistically. This composite approach creates a more robust protective film with enhanced stability and resistance to decomposition at high potentials, resolving the contradiction between film formation and long-term durability
Solution Approach 2:
The patent optimizes the chemical composition and concentration ratios of the electrolyte components to achieve optimal protective film properties. By carefully controlling the parameters of the electrolyte system, it forms a protective film that maintains both effectiveness and stability over extended periods at high voltages
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 electrolyte effectively inhibits solvent decomposition and reduces DC internal resistance, improving the cycle and storage performance of electrochemical devices by forming a stable protective film.
Implementation Method 1
the dinitrile compound can form a protective film on the cathode of the electrochemical device, so as to inhibit the decomposition of the solvent
Implementation Method 2
a firm protective film which is not easily decomposed on the surface of the cathode at a high potential can be formed
Implementation Method 3
The electrolyte according to the embodiment of the present application can effectively inhibit the increase in DC internal resistance
Data Source
AI summary
An electrolyte including a dinitrile compound, a trinitrile compound, and propyl propionate. Based on the total weight of the electrolyte, the weight percentage of the dinitrile compound is X, the weight percentage of the trinitrile compound is Y, and the weight percentage of the propyl propionate is Z, wherein, about 3 wt %≤(X+Y)≤about 11 wt %, about 1≤(X/Y)≤about 6, and about 0.01<(Y/Z)≤about 0.3; the trinitrile compound includes at least one selected from the group of 1,3,5-pentanetricarbonitrile; 1,2,3-propanetrinitrile, 1,3,6-hexanetricarbonitrile; 1,2,6-hexanetricarbonitrile, 1,2,3-tris(2-cyanoethoxy)propane; 1,2,4-tris(2-cyanoethoxy)butane, 1,1,1-tris(cyanoethoxymethylene)ethane, 1,1,1-tris(cyanoethoxymethylene)propane, 3-methyl-1,3,5-tris(cyanoethoxy)pentane, 1,2,7-tris(cyanoethoxy)heptane, 1,2,6-tris(cyanoethoxy)hexane, and 1,2,5-tris(cyanoethoxy)pentane.