Lithium Battery Electrolyte Composition for High Output
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Solution Overview
Problem
Existing lithium secondary batteries face challenges with low ionic conductivity due to high viscosity in carbonate-based solvents and poor cycle characteristics in lithium manganese oxides, making them unsuitable for high-output applications like hybrid electric vehicles.
Innovation Solution
An electrolyte composition of 10 wt % to 90 wt % ester-based solvent and 10 wt % to 90 wt % carbonate-based solvent, specifically 60 wt % ester-based solvent and 40 wt % carbonate-based solvent, is used to enhance ionic conductivity, combined with lithium metal phosphate and amorphous carbon, to improve output characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carbonate based solvent is used as non-aqueous electrolyte, then the electrolyte can provide basic battery operation voltage range, but the ionic conductivity decreases due to increased viscosity
Solution Approach 1:
The patent combines carbonate based solvent and ester based solvent to create a composite electrolyte system. This composite approach allows the electrolyte to maintain the voltage stability provided by carbonate solvents while gaining the lower viscosity and higher ionic conductivity characteristics of ester solvents, thereby resolving the contradiction between voltage range reliability and ionic conductivity.
Solution Approach 2:
The patent modifies the physical and chemical parameters of the electrolyte by changing the solvent composition ratio. By adjusting the proportion of ester based solvent (10-90 wt%) in the electrolyte mixture, the patent optimizes both viscosity and ionic conductivity while maintaining operational voltage characteristics, demonstrating parameter change as a solution to the contradiction.
2Use of energy by moving object
If LiCoO2 is used as cathode active material, then the battery exhibits superior energy density and high-temperature characteristics, but the output characteristics are poor
Solution Approach 1:
The patent uses a composite cathode material consisting of LiCoO2 particles coated with LiMn1.3Ni0.1Co0.6O4 spinel layer. This composite structure allows the core LiCoO2 to provide high energy density while the outer spinel coating layer provides excellent output characteristics and high-temperature stability, thereby resolving the contradiction between energy density and power output.
Solution Approach 2:
The cathode active material is segmented into a core-shell structure where LiCoO2 forms the core for energy storage and LiMn1.3Ni0.1Co0.6O4 forms the shell for rapid ion transport. This segmentation allows each component to perform its specialized function, with the core providing energy density and the shell providing power output characteristics.
3Power
If LiMnO2, LiMn2O4 are used as cathode active material, then the battery can provide high output, but the cycle characteristics are poor
Solution Approach 1:
The patent creates a composite cathode material where LiMn1.3Ni0.1Co0.6O4 spinel phase is combined with LiCoO2 layered structure. The spinel phase provides high output characteristics while the layered LiCoO2 structure provides superior cycle stability. This composite material resolves the contradiction between high output and good cycle characteristics by integrating the advantages of both material systems.
Solution Approach 2:
The cathode material exhibits local quality differentiation where different regions have different compositions and functions. The LiMn1.3Ni0.1Co0.6O4 spinel regions provide high power output while the LiCoO2 layered regions provide long-term cycle stability, allowing the overall material to simultaneously achieve both high output and excellent cycle characteristics.
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 composition significantly improves ionic conductivity and output characteristics, particularly at low temperatures, reducing internal resistance and enhancing high-temperature stability, making the battery suitable for hybrid electric vehicles.
Implementation Method 1
the electrolyte including 10 wt % to 90 wt % of an ester based solvent and 10 wt % to 90 wt % of a carbonate based solvent with respect to the total weight of a non-aqueous solvent
Data Source
AI summary
Disclosed are an electrolyte for lithium secondary batteries including 10 wt % to 90 wt % of an ester based solvent and 10 wt % to 90 wt % of a carbonate based solvent with respect to the total weight of a non-aqueous solvent, and a lithium secondary battery including the same.