Electrolyte Additive Decomposition Potential for Battery Safety
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Solution Overview
Problem
Lithium secondary batteries face issues with gas generation due to reactions between electrodes and electrolytes, leading to potential swelling and explosion, necessitating a solution to prevent such reactions and enhance safety and lifespan.
Innovation Solution
Incorporating an electrolyte additive decomposed at 4.5 V to 5.5 V vs. reduction voltage of Li+, which forms a solid electrolyte interface (SEI) film on the electrodes, suppressing oxidation and preventing gas generation, with optimal additive amounts between 0.1 to 1 wt% to maintain conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an electrolyte additive is used to form a protective film on electrodes, then gas generation is prevented and safety is improved, but internal resistance increases and conductivity decreases
Solution Approach 1:
The patent changes the decomposition potential parameter of the electrolyte additive from conventional ranges to specifically 4.5V or higher to less than 5.5V vs Li+/Li. This parameter change enables the additive to form a protective film at the appropriate potential window, preventing gas generation while minimizing impact on conductivity and internal resistance.
Solution Approach 2:
The electrolyte additive forms a localized protective film (SEI layer) specifically on the electrode surfaces where decomposition occurs at 4.5-5.5V. This localized action prevents gas generation at the electrode-electrolyte interface without affecting the bulk electrolyte conductivity, thus resolving the contradiction between safety improvement and energy loss.
2Object-generated harmful factors
If the amount of electrolyte additive is increased to enhance film formation, then gas generation is suppressed, but conductivity of the electrolyte is reduced
Solution Approach 1:
The patent optimizes the concentration parameter of the electrolyte additive to a specific range (0.1-5 wt%). Within this range, the additive decomposes at 4.5-5.5V to form sufficient protective film to suppress gas generation, while maintaining electrolyte conductivity by avoiding excessive additive concentration that would cause over-decomposition and increased internal resistance.
3Stability of the object's composition
If an electrolyte additive decomposed at lower potential is used, then film formation is easier, but oxidation of electrolyte occurs due to side reactions
Solution Approach 1:
The patent changes the decomposition potential parameter to 4.5V or higher to less than 5.5V vs Li+/Li, which is strategically positioned above the oxidation potential of conventional electrolytes. This parameter change ensures that the additive decomposes to form a stable protective film before electrolyte oxidation can occur, preventing harmful side reactions while achieving effective film formation.
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 additive effectively forms a stable electrode surface layer, reducing side reactions, enhancing safety and lifespan characteristics of the secondary battery by preventing additional oxidation and maintaining conductivity.
Implementation Method 1
the electrolyte includes an electrolyte additive that is decomposed at 4.5 V or higher to less than 5.5 V vs. reduction voltage of Li+
Implementation Method 2
The electrolyte additive is decomposed at 4.5 V or higher to less than 5.5 V vs. reduction voltage of Li+ and thus may form an electrode surface layer such as a solid electrolyte interface (SEI) film
Implementation Method 3
the electrolyte additive may suppress oxidation of the electrolyte due to side reaction between an electrode and the electrolyte
Data Source
AI summary
Disclosed is a secondary battery including a cathode, an anode, and an electrolyte including a lithium salt and a non-aqueous organic solvent, wherein the electrolyte includes an electrolyte additive to be decomposed at 4.5 V or higher to less than 5.5 V vs. reduction voltage of Li+.