Secondary Battery Electrolyte Composition for Wide-Temperature Discharge
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Solution Overview
Problem
Lithium-ion batteries face challenges in achieving high current discharge performance, low-temperature performance, and high-temperature life performance due to the corrosion of positive electrode current collectors and the instability of nonaqueous electrolytes.
Innovation Solution
A secondary battery is developed with a nonaqueous electrolyte composed of a solvent mixture including ethyl propionate, propyl propionate, or ethyl butyrate, and γ-butyrolactone, along with lithium bisfluorosulfonylimide as the electrolyte, which enhances ion conductivity and electrochemical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional nonaqueous electrolytes are used, then basic battery operation is maintained, but high current discharge performance deteriorates due to electrolyte instability and current collector corrosion
Solution Approach 1:
The patent changes the chemical composition parameters of the nonaqueous electrolyte by incorporating specific esters (ethyl propionate, propyl propionate, or ethyl butyrate) in combination with cyclic carbonates and chain carbonates. This parameter change in electrolyte composition improves high current discharge performance while maintaining stability, resolving the contradiction between productivity and reliability.
Solution Approach 2:
The patent uses a composite electrolyte system combining multiple components: esters (ethyl propionate/propyl propionate/ethyl butyrate), cyclic carbonates (ethylene carbonate, propylene carbonate), and chain carbonates (dimethyl carbonate, diethyl carbonate). This composite material approach enhances both the discharge performance and stability, simultaneously addressing the contradictory requirements.
2Productivity
If conventional electrolytes are used, then basic low-temperature operation is maintained, but low-temperature performance deteriorates due to increased viscosity and reduced ion conductivity
Solution Approach 1:
The patent modifies the electrolyte composition by adding esters with lower viscosity (ethyl propionate, propyl propionate, or ethyl butyrate) to the conventional carbonate mixture. This parameter change reduces the overall viscosity of the electrolyte, improving ion conductivity and low-temperature performance while maintaining composition stability.
Solution Approach 2:
The patent creates a composite electrolyte formulation that combines low-viscosity esters with cyclic and chain carbonates. This composite structure balances the viscous properties of carbonates with the fluidity of esters, achieving improved low-temperature performance without compromising composition stability.
3Duration of action of stationary object
If conventional electrolytes are used, then basic high-temperature operation is maintained, but high-temperature life performance deteriorates due to current collector corrosion and electrolyte decomposition
Solution Approach 1:
The patent changes the chemical composition of the electrolyte by incorporating esters (ethyl propionate, propyl propionate, or ethyl butyrate) that form protective films on the current collector surface. This parameter change reduces corrosion rates and electrolyte decomposition at high temperatures, extending battery life performance.
Solution Approach 2:
The ester components act as intermediary substances that form protective interface layers between the electrolyte and the current collector. These intermediary layers prevent direct contact and corrosion reactions, reducing harmful effects at high temperatures while maintaining ionic conductivity.
4Reliability
If nonvolatile and non-flammable electrolytic solutions are used, then safety performance is improved, but output properties and long-life performance deteriorate
Solution Approach 1:
The patent develops a composite electrolyte system that combines esters, cyclic carbonates, and chain carbonates in specific proportions. This composite formulation achieves a balance between safety (non-flammability) and performance (output properties), resolving the contradiction by optimizing the synergistic effects of multiple components.
Solution Approach 2:
The patent optimizes the compositional parameters of the electrolyte, specifically the ratios of esters to carbonates, to achieve both safety and performance requirements. By adjusting these parameters, the electrolyte maintains non-flammability while preserving adequate output properties and cycle 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 battery achieves excellent high current performance, low-temperature performance, and high-temperature life performance, with improved durability and cycle life across a wide temperature range.
Implementation Method 1
The nonaqueous electrolyte includes a nonaqueous solvent and an electrolyte. The electrolyte includes lithium bisfluorosulfonylimide.
Implementation Method 2
a positive electrode including LiCoO2 or LiMn2O4 as an active material
Data Source
AI summary
In general, according to one embodiment, a secondary battery includes a positive electrode, a negative electrode, and a nonaqueous electrolyte. The nonaqueous electrolyte includes a nonaqueous solvent and an electrolyte. The nonaqueous solvent includes a first solvent including at least one selected from the group consisting of ethyl propionate, propyl propionate and ethyl butyrate, and a second solvent including γ-butyrolactone. The electrolyte includes lithium bisfluorosulfonylimide.