Lithium Battery Electrolyte Composition for High-Temperature SEI Stability
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Solution Overview
Problem
Lithium secondary batteries face structural deformation and side reactions due to high-temperature environments, leading to reduced lifespan and increased internal resistance, particularly when using lithium metal oxide particles as cathode active material.
Innovation Solution
An electrolyte solution comprising a lithium salt, organic solvent, and a specific compound represented by Chemical Formula 1, which forms a robust solid electrolyte interphase (SEI) on the electrode surface, suppressing solvent decomposition and side reactions, and including auxiliary additives like fluorine-containing cyclic carbonate-based compounds to enhance stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium metal oxide particles are used as cathode active material, then high operational voltage and energy density are achieved, but structural deformation and side reactions occur during repeated charging and discharging
Solution Approach 1:
The patent introduces a fluorinated cyclic carbonate compound as an intermediary substance between the lithium metal oxide cathode and the electrolyte solution. This compound forms a stable interface layer that mediates interactions, preventing direct harmful reactions while allowing ionic transport, thus resolving the contradiction between high energy density and structural stability
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte by incorporating fluorinated cyclic carbonate compounds with specific molecular structures (containing F atoms and cyclic carbonate groups). This parameter change in the electrolyte composition leads to formation of a more stable SEI layer, improving cathode structural stability during cycling
2Power
If lithium secondary battery is exposed to high-temperature environment during repeated charging/discharging, then high power output is achieved, but battery expansion and increase of internal resistance occur
Solution Approach 1:
The patent applies preliminary action by having the fluorinated cyclic carbonate compound proactively form a stable protective SEI layer on the cathode surface before high-temperature operation begins. This pre-formed stable interface prevents subsequent thermal degradation, battery expansion, and internal resistance increase during high-power discharge
Solution Approach 2:
The patent creates a composite interface structure consisting of the fluorinated cyclic carbonate compound integrated into the SEI layer on the cathode surface. This composite structure combines the electrochemical activity of the cathode with the thermal stability of the fluorinated compound, enabling high power output without dimensional instability
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 solution improves the lifespan and high-temperature storage properties of lithium secondary batteries by forming a stable SEI, reducing resistance and gas generation, and maintaining performance across varying temperature conditions.
Implementation Method 1
A lithium secondary battery according to example embodiments includes the electrolyte solution to have improved life-span and high-temperature storage properties. The electrolyte solution may form a solid electrolyte interphase (SEI) on an electrode surface. The SEI may suppress decomposition of an organic solvent in the electrolyte solution during operation of a lithium secondary battery, and may also suppress side reactions between the electrolyte solution and a cathode active material
Data Source
Figure 1~2
AI summary
An electrolyte for a lithium secondary battery includes a lithium salt, an organic solvent, and a compound represented by a certain chemical formula. A lithium secondary battery includes a case, an electrode assembly including an anode and a cathode stacked repeatedly and alternately, and the electrolyte solution accommodated in the case together with the electrode assembly.