Nitrile Electrolyte Composition for Stable High-Voltage Cathode Films
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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 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
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 on the surface of the cathode at high potential, causing the inhibition effect to be unsustainable
Solution Approach 1:
The patent uses a composite electrolyte system containing both dinitrile compounds and trinitrile compounds together with propyl propionate. The dinitrile compound forms the initial protective film while the trinitrile compound provides sustained stability at high potential, creating a synergistic composite protection mechanism that resolves the contradiction between initial protection effectiveness and long-term sustainability.
Solution Approach 2:
The patent changes the chemical composition parameters of the electrolyte by introducing trinitrile compounds with higher nitrogen content and different molecular structure characteristics. This parameter change enables the formation of a more stable protective film that can withstand high potential conditions sustained over time, addressing the decomposition issue of single-component films.
2Quantity of substance
If high-voltage electrochemical devices are developed to increase capacity density, then the capacity density increases, but the oxidation activity of the positive electrode material increases and stability decreases, leading to electrolyte decomposition
Solution Approach 1:
The patent introduces the electrolyte composition containing dinitrile compounds, trinitrile compounds, and propyl propionate as an intermediary between the high-voltage positive electrode and the solvent. This intermediary forms a stable protective interface that mediates the interaction, allowing high capacity density operation while preventing direct harmful oxidation reactions between the electrode and electrolyte solvent.
3Reliability
If the protective film is formed to inhibit solvent decomposition, then the battery capacity is maintained, but the DC internal resistance increases
Solution Approach 1:
The patent optimizes the concentration ratios and molecular structure parameters of the electrolyte components. By carefully controlling the proportions of dinitrile compounds, trinitrile compounds, and propyl propionate, the protective film achieves adequate protection while maintaining sufficient ionic conductivity, thus balancing capacity retention with acceptable internal resistance levels.
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 better capacity density, cycle performance, and storage reliability in high-voltage electrochemical devices by forming a stable protective film that sustains over time.
Implementation Method 1
the dinitrile compound can form a protective film on the cathode of the electrochemical device
Implementation Method 2
the protective film itself is decomposed on the surface of the cathode at a high potential
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 8 wt %, about 0.1≤(X/Y)≤about 6, about 2 wt %<X≤about 6 wt %, about 30 wt %≤Z≤about 50 wt %, and about 0.01≤(Y/Z)≤about 0.3; wherein the dinitrile compound is one or more compounds selected from butanedinitrile, adiponitrile, 1,4-dicyano-2-butene, and ethylene glycol bis(2-cyanoethyl) ether; and the trinitrile compound is one or more compounds selected from 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; 1,2,5-tris(cyanoethoxy)pentane; and any combination thereof.