Cyano-Group Electrolyte Additive for Lithium Battery Stability
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Solution Overview
Problem
Lithium secondary batteries face challenges with electrode stability and safety during high-voltage charging, particularly at high temperatures, due to decomposition reactions and metal ion precipitation, leading to reduced cycle life and potential fire or explosion risks.
Innovation Solution
A non-aqueous electrolyte solution containing a compound with at least two cyano groups, which forms an ionic conductive film to suppress metal ion deposition and decomposition reactions, enhancing safety and cycle life by stabilizing the electrode interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If charging potential is raised to increase capacity, then battery capacity increases, but electrode structural stability degrades and transition metals are released
Solution Approach 1:
A compound containing at least two cyano groups is introduced as an intermediary substance in the electrolyte solution. This compound mediates between the electrode and electrolyte by forming a stable complex film on the electrode surface, preventing direct harmful interactions while allowing charge transfer, thus enabling high voltage charging without electrode degradation
Solution Approach 2:
The invention changes the chemical composition parameters of the electrolyte solution by introducing a specific compound with at least two cyano groups (—CN). This parameter change modifies the electrolyte's interaction characteristics with the electrode, forming a protective interface layer that stabilizes the electrode structure during high-voltage operation
2Reliability
If the battery is stored for a long period at high temperatures, then energy storage capability is maintained, but gas generation occurs causing battery structure deformation
Solution Approach 1:
The compound with at least two cyano groups acts as a protective intermediary that forms a stable film on the electrode surface, preventing direct oxidation reactions between the electrolyte and electrode during high-temperature storage. This intermediary layer blocks the reaction pathway that would otherwise produce gas and deform the battery structure
Solution Approach 2:
The compound performs preliminary protective action by forming a stable complex film on the electrode surface before any degradation reactions can occur. This pre-formed protective layer prevents subsequent oxidation reactions and gas generation during long-term high-temperature storage
3Quantity of substance
If overcharging occurs at high voltage, then battery capacity is maximized, but electrolyte decomposition occurs and fire or explosion may occur
Solution Approach 1:
The compound with at least two cyano groups serves as a safety intermediary that forms a protective film on the electrode surface, preventing direct contact and violent reactions between the electrolyte and electrode during overcharging conditions. This intermediary layer acts as a thermal and chemical barrier that prevents runaway reactions
Solution Approach 2:
The compound provides beforehand cushioning by forming a stable protective film that cushions against the harmful effects of overcharging. This pre-formed film absorbs and dissipates excess energy and prevents the electrolyte decomposition that would otherwise lead to fire or explosion
4Quantity of substance
If lithium is precipitated on the negative electrode surface, then charge capacity increases, but reaction with electrolyte increases reducing battery life
Solution Approach 1:
The compound with at least two cyano groups acts as an intermediary that forms a stable complex film on the negative electrode surface where lithium precipitates. This film prevents direct contact between the lithium and electrolyte, eliminating the harmful reactions that would otherwise reduce battery life while maintaining charge capacity
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 effectively prevents metal ion dispersion and electrolyte decomposition, improving overcharge safety and high-temperature storage performance, resulting in enhanced cycle characteristics and safety for lithium secondary batteries during high-voltage charging.
Implementation Method 1
suppress electrodeposition of metal ions on a negative electrode by forming a complex with the metal ions dissolved from a positive electrode to form an ionic conductive film
Implementation Method 2
suppress the decomposition reaction of the electrolyte solution by preventing the contact between the positive electrode and the electrolyte solution
Data Source
AI summary
The present invention relates to an additive for a non-aqueous electrolyte solution including a compound represented by Formula 1 below, a non-aqueous electrolyte solution for a lithium secondary battery including the same, and a lithium secondary battery including the non-aqueous electrolyte solution.NC—(R)n—CN [Formula 1](in Formula 1,R is a cycloalkylene group having 3 to 6 carbon atoms in which at least one cyano group (—CN) is substituted or unsubstituted, a haloalkylene group having 2 to 5 carbon atoms in which at least one cyano group (—CN) is substituted or unsubstituted, or an alkylene group having 2 to 5 carbon atoms in which at least one cyano group (—CN) is substituted, and n is an integer of 1 to 5.)