High-Loading Lithium Secondary Battery Electrolyte for Hot Cycling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing lithium secondary batteries face challenges with structural instability and low energy density due to the use of lithium-containing cobalt oxide and nickel-based lithium transition metal oxides, leading to issues like structural deformation, oxygen release, and rapid performance degradation at high temperatures, especially in applications requiring high output, such as electric vehicles.
Innovation Solution
A lithium secondary battery design incorporating a high-loading positive electrode with lithium iron phosphorous oxide, a specific electrolyte composition including a cyclic lactone compound and lithium nitrate, and a sulfonyl imide compound to enhance electrolyte impregnation and charge transfer properties, forming a stable film on the electrode surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a high-loading electrode is designed to increase the degree of application of active material and increase electrode density, then energy density is improved, but electrolyte impregnation properties are degraded
Solution Approach 1:
The patent changes the physical and chemical parameters of the electrolyte by introducing a cyclic carboxylate component with specific molecular structure and properties. This component has high dielectric constant and strong solvation ability, which modifies the electrolyte's viscosity, ion conductivity, and wetting characteristics to enable effective impregnation of high-loading electrodes
Solution Approach 2:
The patent creates a composite electrolyte system by combining cyclic carboxylate (such as γ-butyrolactone) with conventional carbonate solvents and lithium salts. This composite approach leverages the complementary properties of different components: cyclic carboxylate provides high dielectric constant and solvation ability, while carbonate solvents provide low viscosity and good ion mobility
2Quantity of substance
If lithium-containing cobalt oxide or nickel-based lithium transition metal oxide is used as positive electrode active material to achieve high energy density and output, then energy density and output properties are improved, but structural stability deteriorates at high temperature and high voltage
Solution Approach 1:
The cyclic carboxylate component acts as an intermediary between the positive electrode active material and the electrolyte. It forms a stable interfacial layer that prevents direct contact and harmful reactions between the electrolyte and the electrode material, thereby protecting the structural stability of lithium-containing cobalt oxide or nickel-based lithium transition metal oxide at high temperature and high voltage conditions
3Quantity of substance
If the amount of electrode active material coated per area is increased to increase electrode density, then energy density is improved, but charge transfer properties are degraded due to insufficient porous structure
Solution Approach 1:
The patent utilizes the hydraulic properties of the cyclic carboxylate-based electrolyte to improve charge transfer. The electrolyte's low viscosity and high wetting ability enable it to penetrate deeply into the porous structure of high-loading electrodes, ensuring adequate electrolyte distribution and maintaining efficient lithium ion transport pathways even when electrode density is increased
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 design improves electrolyte impregnation and charge transfer, maintaining high-temperature stability and cycle capacity retention, reducing resistance, and ensuring excellent cycle properties.
Implementation Method 1
a specific electrolyte composition including a cyclic lactone compound and lithium nitrate, and a sulfonyl imide compound to enhance electrolyte impregnation and charge transfer properties, forming a stable film on the electrode surface
Implementation Method 2
a specific electrolyte composition including a cyclic lactone compound and lithium nitrate, and a sulfonyl imide compound to enhance electrolyte impregnation and charge transfer properties
Implementation Method 3
a specific electrolyte composition including a cyclic lactone compound and lithium nitrate, and a sulfonyl imide compound to enhance electrolyte impregnation and charge transfer properties
Data Source
AI summary
The present disclosure relates to a lithium secondary battery with improved high-temperature cycle properties, and specifically, in a lithium secondary battery including a positive electrode, a negative electrode, a separator, and an electrolyte, the positive electrode includes a lithium iron phosphorous oxide as a positive electrode active material, wherein the loading amount of the positive electrode is 32 mg/cm2 to 60 mg/cm2, and the electrolyte includes a lithium salt, a first organic solvent, a second organic solvent, a first additive, and a second additive, wherein the first organic solvent is a cyclic lactone compound, the second organic solvent is a carbonate-based organic solvent, the first additive is a lithium nitrate (LiNO3), and the second additive is a sulfonyl imide compound.