Lithium Battery Electrolyte Additive for High-Temperature Cathode Protection
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Solution Overview
Problem
Lithium secondary batteries face issues with decreased output and capacity due to damage to nickel-based lithium metal oxide cathodes, side reactions, and performance degradation under high-temperature conditions, leading to swelling, increased resistance, and reduced lifespan.
Innovation Solution
An electrolyte for lithium secondary batteries comprising an additive represented by Formula 1, an organic solvent, and a lithium salt, which forms a robust solid electrolyte interphase (SEI) on the electrode surface, improving high-temperature storage characteristics and other performance metrics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If nickel-based lithium metal oxide is used as cathode active material to achieve high capacity, then battery capacity is improved, but surface damage and side reactions occur during repeated charging/discharging leading to performance degradation
Solution Approach 1:
A coating layer comprising at least one of a metal oxide, metal phosphate, metal fluoride, metal carbonate, or metal sulfide is formed on the surface of the nickel-based lithium metal oxide cathode active material. This coating layer acts as an intermediary between the cathode material and electrolyte, preventing direct contact and side reactions while allowing lithium ion diffusion, thereby maintaining high capacity and improving cycle stability
Solution Approach 2:
The cathode active material is designed as a composite structure with a core-shell configuration, where the core is nickel-based lithium metal oxide providing high capacity and the shell is a protective coating layer providing stability. This composite structure combines the advantages of high capacity nickel-based materials with the protective benefits of stable coating materials, resolving the contradiction between capacity and surface stability
2Productivity
If repeated charging/discharging is performed to achieve high productivity, then battery output is improved, but swelling phenomenon and internal resistance increase occur due to gas generation and side reactions
Solution Approach 1:
The coating layer on the cathode surface and the specific electrolyte composition act as intermediaries that prevent harmful side reactions between the electrode materials and electrolyte during rapid charging/discharging. This prevents gas generation that causes swelling and reduces internal resistance increase, enabling high productivity without the harmful effects
Solution Approach 2:
The electrolyte is formulated with specific components and concentrations (including lithium salt at 0.5-2.0 M, and additives at controlled ratios) to optimize its properties for rapid charging/discharging conditions. This parameter optimization allows the battery to withstand high current rates while minimizing swelling and resistance increase through controlled electrochemical reactions
3Power
If high-temperature operation is tolerated to achieve high power output, then battery power is improved, but lifespan characteristics deteriorate due to accelerated side reactions
Solution Approach 1:
The protective coating layer on the cathode serves as a thermal barrier and chemical protector that prevents accelerated degradation reactions at high temperatures. This intermediary layer allows the battery to operate at high power outputs while protecting the electrode materials from thermal and chemical damage, thereby maintaining lifespan characteristics even under high-temperature conditions
Solution Approach 2:
The electrolyte composition is specifically designed with additives and solvents that maintain stability at elevated temperatures. By adjusting the electrolyte parameters (component ratios, concentration, and type), the battery can sustain high power output at high temperatures without the severe lifespan deterioration that would normally occur, effectively decoupling power and lifespan constraints
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 enhances battery performance by reducing resistance, preventing thickness increase, and improving rapid charging and lifespan characteristics, while maintaining capacity retention at high and low temperatures.
Implementation Method 1
which forms a robust solid electrolyte interphase (SEI) on the electrode surface
Data Source
AI summary
According to exemplary embodiments, an electrolyte for a lithium secondary battery which includes an additive including a compound represented by a specific formula; an organic solvent; and a lithium salt may be provided. Thereby, the lithium secondary battery including the electrolyte for a lithium secondary battery may provide excellent high-temperature characteristics and other performances (e.g., initial resistance, rapid charge performance, room-temperature capacity characteristics, etc.).