Nitrile Electrolyte Composition for High-Voltage DC Resistance Control
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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 battery capacity, as existing solutions fail to sustainably inhibit solvent decomposition and increase DC internal resistance.
Innovation Solution
A lithium secondary battery electrolyte comprising a mixture of dinitrile, trinitrile compounds, and propyl propionate, with specific weight percentage ratios, forms a stable protective film that inhibits solvent decomposition and reduces DC internal resistance, while additional components like fluoroether and cyclic phosphonic anhydride enhance 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 (0.1-5 wt%) and trinitrile compound (0.1-5 wt%) work synergistically with propyl propionate (5-30 wt%) to create a film that is more resistant to decomposition at high potentials than a single-component film, thereby extending the durability of the protective effect.
Solution Approach 2:
The patent optimizes the concentration parameters of the electrolyte components, specifically setting dinitrile compound at 0.1-5 wt%, trinitrile compound at 0.1-5 wt%, and propyl propionate at 5-30 wt%. These parameter adjustments ensure the protective film has appropriate stability and durability characteristics for sustained operation at high voltages.
2Use of energy by moving object
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, leading to electrolyte decomposition
Solution Approach 1:
The dinitrile compound, trinitrile compound, and propyl propionate act as intermediary substances that form a protective interface film between the high-voltage cathode material and the electrolyte solvent. This intermediary film prevents direct contact and oxidation reactions, enabling the system to operate at high voltages (4.4V or higher) without excessive electrolyte decomposition.
Solution Approach 2:
The patent modifies the electrolyte composition parameters by incorporating specific concentrations of dinitrile compound (0.1-5 wt%), trinitrile compound (0.1-5 wt%), and propyl propionate (5-30 wt%). These parameter changes enhance the electrolyte's ability to form stable protective films, thereby improving reliability while maintaining high voltage operation for increased capacity density.
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 maintains battery performance by reducing DC internal resistance and improving cycle and storage capabilities, ensuring high capacity density and reliability at high voltages.
Implementation Method 1
the dinitrile compound, the trinitrile compound and propyl propionate form a protective film on the cathode
Implementation Method 2
The electrolyte according to the embodiment of the present application can effectively inhibit the increase in DC internal resistance of the electrochemical device
Data Source
Figure 1a
Figure 1b~1c
Figure 2~4
AI summary
An electrolyte includes a dinitrile compound, a trinitrile compound, and propyl propionate. Based on the total weight of the electrolyte, the content X of the nitrile compound and the content Y of the trinitrile compound meet the conditions represented by Formula (1) and Formula (2): {about 2 wt% ≤ (X+Y) ≤ about llwt% ...(1), about 0.1 ≤ (X/Y) ≤ about 8 ...(2)}. The trinitrile compound includes a compound of Formula (6) or (7).The electrolyte is capable of effectively inhibiting the increase in DC internal resistance of an electrochemical device so that the electrochemical device has excellent cycle and storage performance.