Electrolyte Composition for Stable High-Voltage Cathode Protection
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Solution Overview
Problem
High-voltage electrochemical devices face issues with increased oxidation activity and stability of positive electrode materials, leading to electrolyte decomposition and decreased battery capacity, which existing solutions fail to adequately address without increasing DC internal resistance.
Innovation Solution
An electrolyte comprising a dinitrile compound, a trinitrile compound, and propyl propionate, within specific weight percentage ranges, forms a protective film that inhibits solvent decomposition and reduces DC internal resistance, while additional components like fluoroether and cyclic phosphonic anhydride enhance long-term storage performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dinitrile compound is used to form a protective film on the cathode, then the decomposition of the solvent is inhibited, but the protective film itself decomposes at high potential, causing the inhibition effect to be unsustainable
Solution Approach 1:
The patent combines dinitrile compound, trinitrile compound, and propyl propionate to form a composite protective film. The dinitrile compound provides initial film formation and solvent decomposition inhibition, while the trinitrile compound and propyl propionate replenish and maintain the film at high potentials, creating a synergistic system that sustains protection over time.
Solution Approach 2:
The patent optimizes the weight percentages of dinitrile compound (0.01-10 wt%) and trinitrile compound (0.01-10 wt%) to achieve the right balance between initial film formation capability and long-term sustainability. This parameter optimization ensures the protective film remains stable and functional at high potentials throughout the battery's operational life.
2Quantity of substance
If high-voltage electrochemical devices are developed to increase capacity density, then the energy storage capability is improved, but the oxidation activity of positive electrode material increases and stability decreases, leading to electrolyte decomposition
Solution Approach 1:
The dinitrile compound acts as an intermediary substance that forms a protective interface film between the positive electrode material and the electrolyte. This film mediates the interaction, preventing direct contact and chemical reactions between the high-voltage electrode material and the electrolyte, thereby suppressing oxidation and decomposition while allowing the high-voltage device to operate at its full capacity density potential.
3Reliability
If the concentration of dinitrile compound and trinitrile compound is increased to improve protective film formation, then the inhibition of solvent decomposition is enhanced, but the DC internal resistance increases
Solution Approach 1:
The patent precisely controls the concentration parameters of dinitrile compound (0.01-10 wt%) and trinitrile compound (0.01-10 wt%) to achieve optimal protective film formation. This parameter optimization ensures sufficient film coverage and protection against solvent decomposition while maintaining the film's ionic conductivity, thereby avoiding excessive DC internal resistance.
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 the increase in DC internal resistance, achieving high capacity density and excellent cycle and storage performances by forming a stable protective film that sustains at high potentials.
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
at high voltages, the oxidation activity of the positive electrode material increases, and the stability decreases, which makes the electrolyte decompose on the surface of the positive electrode
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 2 wt %<(X+Y)≤about 11 wt %, about 0.1≤(X/Y)≤about 4, about 30 wt %≤Z≤about 50 wt %, about 2 wt %<X≤about 6 wt %, and about 0.01<(Y/Z)≤about 0.3; wherein the trinitrile compound comprises at least one selected from the group consisting 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.