Battery Electrolyte Composition for High-Temperature Cycling and Low Impedance
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Solution Overview
Problem
Current lithium-ion batteries face challenges in achieving high energy density, superior high-temperature cycle stability, safety, and low impedance simultaneously, which are essential for expanding their application fields.
Innovation Solution
The electrochemical device incorporates a fluorine-substituted linear carboxylate ester in the electrolyte and a nickel-containing positive active material, with specific mass percentages and coating weights, to enhance high-temperature cycle performance and reduce impedance while maintaining high energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the energy density of lithium-ion batteries is increased, then the battery capacity is improved, but the high-temperature cycle stability and safety deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing fluorine-substituted linear carboxylate esters with specific molecular structures (Formula I and II) and controlling their content within 5-50 wt%, which modifies the electrolyte's chemical properties to achieve both high capacity and high-temperature stability
Solution Approach 2:
The patent creates a composite electrolyte system combining fluorine-substituted linear carboxylate esters with conventional carbonate solvents (EC, PC, DEC, EMC) and lithium salts (LiPF6, LiBF4), where the composite formulation synergistically provides high energy density support and thermal stability
2Quantity of substance
If the energy density is increased, then the battery performance is improved, but the impedance increases
Solution Approach 1:
The patent optimizes the molecular structure parameters of the electrolyte additives by using fluorine-substituted linear carboxylate esters with specific chain lengths and substitution patterns, which changes the electrochemical interface properties to reduce impedance while maintaining high capacity
Solution Approach 2:
The fluorine-substituted linear carboxylate esters act as intermediary substances that mediate between the electrode and conventional electrolyte, forming protective interface layers that reduce impedance without compromising the battery's energy storage capacity
3Ease of manufacture
If conventional electrolyte compositions are used, then the manufacturing is simple, but the high-temperature cycle performance is poor
Solution Approach 1:
The patent modifies the electrolyte composition parameters by incorporating fluorine-substituted linear carboxylate esters at controlled concentrations (5-50 wt%), which maintains the simplicity of electrolyte preparation processes while dramatically improving high-temperature cycle performance through enhanced chemical 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
This configuration results in improved high-temperature cycle capacity retention, reduced gas production, and lower impedance, ensuring excellent kinetic performance and stability of the electrochemical device.
Implementation Method 1
adjusts constituents of an electrolyte, constituents of a positive active material, and coordination between the electrolyte and a positive electrode, so as to improve the high-temperature cycle performance, suppress swelling, and reduce the impedance
Implementation Method 2
Rechargeable lithium-ion batteries (LIBs) are considered to be one of the most attractive energy storage systems
Implementation Method 3
The positive active material layer includes a nickel-containing positive active material
Data Source
AI summary
An electrochemical device includes a positive electrode, a negative electrode, and an electrolyte. The electrolyte includes a fluorine-substituted linear carboxylate ester. Based on a total mass of the electrolyte, a mass percent of the fluorine-substituted linear carboxylate ester is a %, satisfying: 10≤a≤70. The positive electrode includes a positive current collector and a positive active material layer applied onto at least one surface of the positive current collector. The positive active material layer includes a nickel-containing positive active material. Based on a total mass of the positive active material layer, a mass percent of nickel is x %, satisfying: 33≤x≤55. A coating weight of the positive active material applied on the positive current collector is w (mg/cm2), satisfying: 6.5≤w≤19.5, and 1.0≤a/w≤8.2.