Lithium Battery Electrolyte Additive for SEI Stability
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Solution Overview
Problem
Lithium secondary batteries face challenges in maintaining performance under extreme conditions such as overcharge, overdischarge, and high-temperature storage due to corrosion of metallic materials and insufficient stability of the Solid Electrolyte Interface (SEI) film and protective layers.
Innovation Solution
An electrolyte solution for lithium secondary batteries is developed, incorporating a compound with a sulfonate group and an isocyanate group as additives, which form stable SEI and protective films on electrode surfaces, preventing chemical reactions and enhancing high-temperature stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolyte solutions are used in lithium secondary batteries, then the batteries can operate at high driving voltage, but the SEI film and protective layer formed during initial charging have insufficient stability and high resistance, leading to poor cycle life and high-temperature durability
Solution Approach 1:
The patent modifies the chemical composition parameters of the electrolyte by introducing a specific additive (compound with isocyanate and sulfonate groups) to change the properties of the formed SEI film and protective layer. This additive alters the formation mechanism of these films, resulting in improved stability and lower resistance without changing the basic electrolyte system.
Solution Approach 2:
The patent creates a composite electrolyte system by combining conventional electrolyte components with a specially designed additive compound. This composite approach allows the electrolyte to form composite SEI films and protective layers that combine the benefits of conventional electrolytes with the stabilizing effects of the additive, achieving both high voltage operation and improved durability.
2Productivity
If conventional electrolyte solutions are used in lithium secondary batteries, then the batteries can be charged and discharged, but excessive charge is consumed due to side reactions between electrodes and electrolyte during initial charging
Solution Approach 1:
The patent changes the chemical parameters of the electrolyte by adding a specific compound that modifies the side reaction pathways during initial charging. This additive reduces the extent of irreversible reactions between the electrolyte and electrodes, thereby decreasing charge consumption and improving overall charge-discharge efficiency.
3Reliability
If stable SEI film and protective layer are formed to improve battery life, then corrosion of metallic materials is reduced, but the electrolyte composition becomes more complex
Solution Approach 1:
The patent uses parameter changes by introducing a single multifunctional additive compound that simultaneously provides multiple benefits: forming stable SEI films, protecting metallic materials from corrosion, and improving high-temperature durability. This approach achieves complex protective functions through a relatively simple compositional modification.
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 the cycle life and high-temperature durability of lithium secondary batteries by forming stable films that reduce corrosion and gas generation, maintaining performance even under extreme conditions.
Implementation Method 1
an irreversible reaction in which an excessive amount of charge is used occurs due to a side reaction between a negative electrode/a positive electrode and an electrolyte solution during initial charging. Due to the irreversible reaction, a passivation layer such as a solid electrolyte interface (SEI) (hereinafter referred to as an "SEI film") is formed at a negative electrode surface, and a protective layer is formed at a positive electrode surface.
Implementation Method 2
the electrolyte solution further including a compound represented by Chemical Formula 1 or Chemical Formula 1a as an electrolyte additive
Implementation Method 3
The SEI film and the protective layer prevent decomposition of an electrolyte solution during charging and discharging and serve as an ion tunnel.
Data Source
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AI summary
The present invention relates to an electrolyte solution for a lithium secondary battery that includes an additive for forming a stable SEI film and a protective layer on a surface of an electrode to prevent a chemical reaction between the electrolyte solution and the electrode, and a lithium secondary battery having improved life characteristics and high-temperature stability by including the same.