Non-aqueous Electrolyte Coating for High-Temperature Battery Stability
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Solution Overview
Problem
Conventional lithium secondary batteries experience deteriorated cycle characteristics and increased internal resistance in high-temperature environments, leading to reduced performance and capacity loss, despite previous attempts to improve durability and storage performance.
Innovation Solution
A non-aqueous electrolytic solution comprising at least one compound represented by the general Formula (Mn+) and cyclic carbonates with an unsaturated bond, such as lithium diethyl phosphate and vinylene carbonate, is used to form a coating on the electrode active materials, enhancing thermal stability and coating quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional electrolytic solutions are used in high-temperature environments, then the battery can operate at high temperatures, but the cycle characteristics deteriorate and internal resistance increases
Solution Approach 1:
The patent introduces a coating layer formed by vinylene carbonate and fluorinated cyclic carbonate additives as an intermediary between the electrode active material and the electrolytic solution. This coating layer mediates the interaction at the interface, preventing direct harmful reactions while maintaining lithium ion conductivity, thus resolving the contradiction between high-temperature operation and cycle stability
Solution Approach 2:
The patent changes the chemical composition parameters of the electrolytic solution by adding specific additives (vinylene carbonate at 0.01-5% and fluorinated cyclic carbonate at 0.01-5%). These parameter changes modify the properties of the formed coating layer, making it more stable at high temperatures while maintaining ion conductivity, thereby improving cycle characteristics
2Quantity of substance
If the cell size is increased for higher capacity, then the energy density improves, but the cell is exposed to higher temperatures due to self-generated heat
Solution Approach 1:
The patent converts the harmful effect of self-generated heat into a beneficial outcome by designing an electrolytic solution that forms a thermally stable coating layer. This coating layer actually improves high-temperature durability and prevents further degradation from heat exposure, turning the heat problem into an opportunity to demonstrate enhanced thermal stability
3Productivity
If charge-discharge cycles are repeated in high-temperature environments, then the battery provides continuous power, but cracks and dissolution occur at the stable interface
Solution Approach 1:
The patent applies preliminary action by forming a stable coating layer on the electrode surface before extensive cycling occurs. This pre-formed protective layer prevents subsequent cracks and dissolution during repeated charge-discharge cycles at high temperatures, maintaining interface stability throughout the battery's operational life
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 significantly improves cycle characteristics and thermal stability of secondary batteries in high-temperature environments, maintaining performance and capacity retention even after repeated charge-discharge cycles.
Implementation Method 1
a non-aqueous electrolytic solution containing a monofluorophosphate or a difluorophosphate as an additive, a coating can be formed on a positive electrode and a negative electrode
Implementation Method 2
The process of insertion in an electrode active material/desertion from an electrode active material of lithium ions is high in reversibility
Data Source
Figure 1
AI summary
Provided are a non-aqueous electrolytic solution for a secondary battery which exhibits excellent cycle characteristics even in high-temperature environments; and a secondary battery including the non-aqueous electrolytic solution. A non-aqueous electrolytic solution for a secondary battery which is used for a secondary battery, comprises the following component (A) and the following component (B), wherein Component (A) is at least one compound represented by the following general Formula (1); and wherein Component (B) is one boron complex salt represented by the following general Formula (2), or at least one type of a compound selected from the group consisting of boric acid esters, acid anhydrides, cyclic carbonates having an unsaturated bond, cyclic carbonates having a halogen atom, cyclic sulfonic acid esters, and amines represented by the general Formula (3) and having an acetoacetyl group.