Lithium Battery Electrolyte Additives for Cathode Side-Reaction Suppression
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Solution Overview
Problem
Lithium secondary batteries experience degradation in stability and cycle life due to side reactions between the cathode active material and the electrolyte during charging and discharging, particularly at low and high temperatures.
Innovation Solution
An electrolyte for lithium secondary batteries comprising an additive with a specific structure, an organic solvent, and a lithium salt, which forms a uniform solid electrolyte interphase (SEI) film on the electrode surface, suppressing side reactions and enhancing ionic conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolyte is used, then the battery can operate, but side reactions occur between cathode active material and electrolyte causing degradation of stability and cycle life
Solution Approach 1:
The patent introduces a coating layer comprising a compound of Formula 1 on the cathode active material surface. This coating acts as an intermediary barrier between the cathode active material and the electrolyte, preventing direct contact and harmful side reactions while allowing lithium ion transport, thus improving stability and cycle life without compromising battery operation
Solution Approach 2:
The coating layer is applied in advance to the cathode active material before battery assembly. This preliminary protective action prevents side reactions from occurring at the interface between the cathode active material and electrolyte, addressing the harmful effect before it can degrade the battery's stability and cycle life
2Ease of operation
If conventional electrolyte is used, then the battery operates, but low-temperature performance is poor due to increased resistance and reduced ionic conductivity
Solution Approach 1:
The patent modifies the electrolyte composition by adding specific additives (cyclic carbonate compounds, chain carbonate compounds, and fluorinated compounds) in controlled ratios. These compositional parameter changes lower the freezing point and maintain ionic conductivity at low temperatures, improving ease of operation without sacrificing reliability
Solution Approach 2:
The electrolyte is formulated as a composite system combining multiple carbonate solvents (cyclic and chain) with specific fluorinated additives. This composite electrolyte composition synergistically improves low-temperature fluidity and ionic conductivity while maintaining stability, resolving the contradiction between operational ease and reliability at low temperatures
3Reliability
If conventional electrolyte is used, then the battery operates, but high-temperature storage properties deteriorate due to accelerated side reactions and electrolyte decomposition
Solution Approach 1:
The coating layer of Formula 1 compound serves as a thermal barrier and protective intermediary between the cathode active material and electrolyte. At high temperatures, this coating prevents accelerated side reactions and electrolyte decomposition, maintaining reliability while the electrolyte composition (with stable carbonate mixtures and fluorinated additives) resists thermal degradation
Solution Approach 2:
The electrolyte composition is optimized with specific ratios of cyclic to chain carbonates (1:4 to 4:1) and fluorinated compound additions (0.1-10 wt%). These parameter changes raise the decomposition temperature and improve thermal stability, enabling the battery to maintain reliability under high-temperature storage conditions without excessive electrolyte decomposition
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 improves low-temperature performance, high-temperature storage properties, and cycle life of lithium secondary batteries by stabilizing the electrode interface and reducing decomposition, thereby enhancing discharge capacity and long-term performance.
Implementation Method 1
the electrolyte for a lithium secondary battery may form a uniform and stable solid electrolyte interphase (SEI) with high ionic conductivity on the electrode surface
Data Source
Figure 1~2
AI summary
An electrolyte for a lithium secondary battery according to exemplary embodiments includes an additive including a compound having a specific structure, an organic solvent and a lithium salt. Accordingly, a lithium secondary battery including the electrolyte for a lithium secondary battery may exhibit improved low-temperature performance and high-temperature stability.