Nitrile Electrolyte Composition for High-Voltage Battery Interface Stability
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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, as existing solutions increase DC internal resistance and affect cycle performance.
Innovation Solution
An electrolyte comprising a dinitrile compound, a trinitrile compound, and propyl propionate, within specific weight percentage ratios, 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
1Quantity of substance
If high-voltage electrochemical devices are used to increase capacity density, then energy storage capacity is improved, but electrolyte decomposition occurs and battery capacity decreases
Solution Approach 1:
The patent introduces a protective film as an intermediary layer between the electrolyte and the positive electrode material. This film, formed by specific additives, acts as a mediator that prevents direct contact and harmful reactions between the electrolyte and high-voltage electrode materials, thereby maintaining electrolyte stability while enabling high-voltage operation for increased capacity density
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte by adding specific compounds (such as fluoroether and cyclic phosphonic anhydride) to change the formation mechanism and composition of the protective film. This parameter change enables the film to form effectively at high voltages without causing electrolyte decomposition, resolving the contradiction between capacity density and electrolyte stability
2Reliability
If protective film is formed to inhibit solvent decomposition, then electrolyte stability is improved, but DC internal resistance increases and cycle performance deteriorates
Solution Approach 1:
The patent creates a protective film with non-uniform local composition and structure - the film has different properties at different locations and depths. The outer layer provides protection against decomposition while the inner layer maintains ion conductivity, thus achieving electrolyte stability without significantly increasing DC internal resistance
Solution Approach 2:
The protective film is formed as a composite structure containing multiple components from the electrolyte additives. This composite material provides both protective functions (inhibiting decomposition) and conductive functions (maintaining low internal resistance), resolving the contradiction between electrolyte stability and cycle performance
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, maintaining battery performance and capacity over cycles, with improved storage and cycle reliability by forming a stable protective film at the electrode interface.
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 in the electrochemical device
Implementation Method 2
At high voltages, the oxidation activity of the positive electrode material increases, and the stability decreases
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 1≤(X/Y)≤about 6, about 40 wt %≤Z≤about 50 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.