Lithium-Ion Electrolyte Additives for High-Temperature Resistance Stability
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Solution Overview
Problem
Lithium ion secondary cells experience increased resistance when stored at high temperatures, despite initial resistance reduction techniques, such as adding acetonitrile to non-aqueous electrolytic solutions, failing to suppress this increase effectively.
Innovation Solution
A non-aqueous electrolytic solution for lithium ion secondary cells incorporating a light metal salt, such as lithium oxalate complexes, and a silyl sulfate compound, within specific concentration ranges, to form a low-resistance coating film that maintains stability at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a light metal salt such as an oxalate complex is included in a non-aqueous electrolytic solution, then cycle characteristic and storage characteristic are improved, but initial resistance is increased
Solution Approach 1:
The patent combines a light metal salt (oxalate complex) with acetonitrile in specific proportions within the electrolytic solution. This merging of components allows the solution to simultaneously achieve improved cycle characteristics from the oxalate complex and reduced initial resistance from acetonitrile, resolving the contradiction between these two opposing effects
Solution Approach 2:
The patent optimizes the concentration parameters of both the light metal salt (0.1-1.5 mass%) and acetonitrile (5-50 mass%) in the electrolytic solution. By precisely controlling these parameter ranges, the solution achieves a balance where cycle characteristics are improved while initial resistance remains low, resolving the technical contradiction through parameter optimization
2Object-generated harmful factors
If acetonitrile is added to reduce initial resistance, then initial resistance decreases, but resistance increases when cell is allowed to stand at high temperature
Solution Approach 1:
The patent merges acetonitrile with a light metal salt (oxalate complex) in specific proportions. The oxalate complex acts as a stabilizing agent that counteracts the temperature-induced resistance increase caused by acetonitrile, while acetonitrile maintains low initial resistance. This combination resolves the contradiction between low initial resistance and high-temperature stability
Solution Approach 2:
The electrolytic solution forms a composite system combining acetonitrile and light metal salt (oxalate complex). This composite material approach allows the solution to exhibit both low initial resistance (from acetonitrile) and high-temperature stability (from the oxalate complex), resolving the technical contradiction through material composition
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 solution reduces initial resistance and suppresses resistance increases when cells are stored at high temperatures, enhancing capacity retention and maintaining low resistance characteristics.
Implementation Method 1
incorporating a light metal salt, such as lithium oxalate complexes, and a silyl sulfate compound, within specific concentration ranges, to form a low-resistance coating film
Implementation Method 2
non-aqueous electrolytic solution for a lithium ion secondary cell
Data Source
AI summary
Provided is a non-aqueous electrolytic solution for a lithium ion secondary cell that can reduce the initial resistance of the lithium ion secondary cell and can suppress the increase in resistance when the lithium ion secondary cell is allowed to stand at high temperature. The non-aqueous electrolytic solution for a lithium ion secondary cell disclosed herein includes a light metal salt represented by the following formula (I) and a silyl sulfate compound represented by the following formula (II). The content of the light metal salt in the non-aqueous electrolytic solution for a lithium ion secondary cell is 0.1% by mass or more and 1.5% by mass or less. The content of the silyl sulfate compound in the non-aqueous electrolytic solution for a lithium ion secondary cell is 0.1% by mass or more and 5.0% by mass or less (each symbol in the formulas is as defined in the specification).