High-Voltage Battery Electrolyte Composition for Stable 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 further enhance stability and 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. 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 resolving the contradiction between achieving high capacity density and maintaining electrolyte stability.
Solution Approach 2:
The patent changes the chemical composition parameters of the electrolyte by adding specific compounds (dinitrile compound, trinitrile compound, and propyl propionate in specific weight ratios). These parameter changes enable the formation of a stable protective film that can withstand high voltages, allowing the system to operate at higher voltages without electrolyte decomposition.
2Reliability
If protective film is formed on cathode surface to inhibit solvent decomposition, then electrolyte stability is improved, but protective film decomposes at high potential and inhibition effect is not sustained
Solution Approach 1:
The patent uses a composite electrolyte system containing multiple components (dinitrile compound, trinitrile compound, propyl propionate) in specific ratios. This composite approach creates a more robust protective film with enhanced stability at high potentials, resolving the issue of film decomposition and ensuring sustained inhibition effect over time.
Solution Approach 2:
The patent optimizes the weight ratio parameters of the electrolyte components (dinitrile compound: 2-11 wt%, trinitrile compound: specific ratio to dinitrile compound, propyl propionate: specific ratio to trinitrile compound). These parameter optimizations ensure the protective film maintains its integrity and inhibition capability even at high potentials, extending its duration of action.
3Reliability
If existing solutions are used to address high-voltage stability, then electrolyte decomposition is reduced, but DC internal resistance increases
Solution Approach 1:
The patent carefully controls the concentration parameters of the electrolyte additives within specific ranges. This precise parameter control allows the formation of a protective film that provides stability without creating excessive resistance, thereby resolving the contradiction between electrolyte stability and DC internal resistance.
Solution Approach 2:
The patent creates a localized protective layer with specific chemical properties on the electrode surface. This local modification provides the necessary stability at the electrode-electrolyte interface without affecting the bulk electrolyte properties excessively, thus maintaining low DC internal resistance while achieving high stability.
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 retention and storage performance by forming a stable protective film that sustains at high potentials, thereby improving the electrochemical device's cycle and storage performance.
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
the electrolyte comprises a compound comprising two cyano groups (herein also referred to as 'a dinitrile compound'), a compound comprising three cyano groups (herein also referred to as 'a trinitrile compound'), and propyl propionate
Implementation Method 3
since the protective film itself is decomposed on the surface of the cathode at a high potential
Implementation Method 4
by using a mixture of a dinitrile compound, a trinitrile compound and propyl propionate, a firm protective film which is not easily decomposed on the surface of the cathode is at a high potential can be formed
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 2.2 wt %≤(X+Y)≤about 8 wt %, about 0.1≤(X/Y)≤about 6, 1 wt %≤Y<5 wt %, about 5 wt %≤Z≤about 50 wt %, and about 0.02<(Y/Z)≤about 0.3. The electrolyte further includes at least one selected from the group consisting of a cyclic carbonate ester having a carbon-carbon double bond, a fluorinated chain carbonate ester, a fluorinated cyclic carbonate ester, and a compound having a sulfur-oxygen double bond.