Nonaqueous electrolyte secondary battery
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Solution Overview
Problem
Conventional nonaqueous electrolyte secondary batteries for hybrid electric vehicles (HEVs) fail to meet the increasing demand for higher output and enhanced capacity deterioration resistance in repetitive charge and discharge with large currents.
Innovation Solution
A nonaqueous electrolyte secondary battery configuration that includes a positive electrode with a carbon nanotube-supported active material layer and a nonaqueous electrolyte containing 2 to 9 volume % of a carboxylate ester with 6 or less carbon atoms, which enhances wettability and conductivity, thereby improving output characteristics and capacity retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional nonaqueous electrolyte secondary batteries use carbonates as nonaqueous solvent and acetylene black as conductive material, then the battery structure is simple and manufacturing is easy, but the output characteristics and capacity deterioration resistance in repetitive charge and discharge with large current are insufficient
Solution Approach 1:
The patent changes the chemical composition parameters of the nonaqueous electrolyte by introducing carboxylate ester (2-9 volume%) with specific carbon atom counts (6 or less) and fluorine substitution options. This parameter change improves capacity deterioration resistance and output characteristics while maintaining manageable device complexity through controlled formulation.
Solution Approach 2:
The patent creates a composite electrolyte system by combining carboxylate ester with conventional carbonate solvents. This composite approach leverages the beneficial properties of both material types - the carboxylate ester provides improved capacity retention and wettability, while the carbonate maintains overall electrolyte stability and conductivity.
2Power
If the battery is designed for high output and repetitive charge/discharge with large current, then the output characteristics improve, but the capacity deterioration resistance deteriorates
Solution Approach 1:
The patent modifies the electrolyte composition parameters by adding carboxylate ester (2-9 volume%) with 6 or less carbon atoms and optional fluorine substitution. This parameter change simultaneously improves both output characteristics and capacity deterioration resistance, resolving the trade-off between power and reliability.
Solution Approach 2:
The patent enhances the local quality of the electrolyte at the electrode interface by using carboxylate ester, which provides superior wettability and forms protective films. This localized improvement at the critical electrode-electrolyte interface enables high output performance while maintaining capacity retention during repetitive large current charge/discharge cycles.
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 battery achieves high output characteristics and significant capacity deterioration resistance in repetitive charge and discharge with large currents, making it suitable for HEV drive power supplies.
Implementation Method 1
The nonaqueous solvent contains 2 to 9 volume % of a carboxylate ester that has 6 or less carbon atoms and may be optionally substituted by a fluorine atom
Implementation Method 2
The positive electrode active material layer contains a positive electrode active material and carbon nanotubes
Data Source
AI summary
Provided is a nonaqueous electrolyte secondary battery having both high output characteristics and high capacity deterioration resistance in repetitive charge and discharge with a large current. A nonaqueous electrolyte secondary battery disclosed here includes a positive electrode, a negative electrode, and a nonaqueous electrolyte. The positive electrode includes a positive electrode current collector and a positive electrode active material layer supported by the positive electrode current collector. The positive electrode active material layer contains a positive electrode active material and carbon nanotubes. The nonaqueous electrolyte contains a nonaqueous solvent and a supporting electrolyte. The nonaqueous solvent contains 2 to 9 volume % of a carboxylate ester that has 6 or less carbon atoms and may be optionally substituted by a fluorine atom.