Electrolyte Additives for High Voltage Battery Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current lithium-ion secondary battery electrolytes, using lithium hexafluorophosphate and cyclic or chain carbonates, face deficiencies in cycle performance and storage performance, especially under high voltage and high temperature conditions.
Innovation Solution
Incorporating a nitrogen-containing six-membered heterocyclic compound with multiple cyano groups and a lithium sulfonimide salt as additives in the electrolyte, which passivates the positive active material surface, suppresses oxidation, and forms a stable SEI film on the negative electrode, thereby enhancing electrochemical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium hexafluorophosphate and cyclic/chain carbonates are used as electrolyte components, then the electrolyte provides basic ionic conductivity, but cycle performance and storage performance deteriorate under high voltage and high temperature conditions
Solution Approach 1:
The patent applies preliminary action by introducing additives (nitrogen-containing heterocyclic compounds with cyano groups and lithium sulfonimide salts) that proactively form protective films on electrode surfaces before degradation can occur. These additives preemptively passivate the positive active material surface and form stable SEI films on the negative electrode, preventing subsequent oxidation and decomposition reactions that would otherwise occur under high temperature and high voltage conditions.
Solution Approach 2:
The patent uses intermediary substances (the nitrogen-containing heterocyclic compound and lithium sulfonimide salt) that mediate between the electrolyte and electrode surfaces. These intermediaries form interfacial protective layers that阻隔 direct contact between the aggressive electrolyte components and the electrodes, thereby improving cycle performance and thermal stability without compromising the basic ionic conductivity function of the electrolyte.
2Reliability
If lithium hexafluorophosphate and cyclic/chain carbonates are used as electrolyte components, then the electrolyte provides basic ionic conductivity, but storage performance deteriorates under high voltage and high temperature conditions
Solution Approach 1:
The patent applies preliminary anti-action by using additives that preemptively counteract oxidation effects. The nitrogen-containing heterocyclic compound with cyano groups preferentially reacts with oxygen and forms protective films on the positive electrode surface, preventing oxygen from attacking and oxidizing the electrolyte components. This preliminary anti-oxidation action significantly improves storage performance under high temperature and high voltage conditions.
3Quantity of substance
If conventional electrolyte components are used, then the electrolyte maintains basic functionality, but gas production increases due to side reactions
Solution Approach 1:
The patent converts the potentially harmful side reactions into beneficial effects. The additives (nitrogen-containing heterocyclic compound and lithium sulfonimide salt) intentionally undergo controlled reactions to form protective films and stable intermediates that prevent more severe degradation reactions. The lithium sulfonimide salt, for example, decomposes at high temperatures to form protective layers instead of generating harmful gases, effectively converting thermal degradation into a protective mechanism.
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 additives significantly improve cycle and storage performance under high temperature and high voltage conditions, reduce gas production, and maintain low temperature performance by stabilizing the electrolyte and reducing side reactions.
Implementation Method 1
the surface of positive active materials can be effectively passivated, the surface activity of positive active materials can be suppressed, the oxidation effect of the positive active materials on the electrolyte can be suppressed
Implementation Method 2
the lithium sulfonamide salt also may particulate in the formulation of SEI film on negative electrode so that the SEI film formed on the negative electrode can hinder the direct contact of the negative electrode with the electrolyte
Implementation Method 3
the electrolyte system in which lithium hexafluorophosphate is used as a conductive lithium salt
Data Source
AI summary
This application provides an electrolyte and an electrochemical device, in which the electrolyte comprises an additive A and an additive B, wherein the additive A is present in an amount of 0.001% to 10% by mass in the electrolyte and the additive B is present in an amount of 0.1% to 10% by mass in the electrolyte and the electrolyte has a conductivity of 4 mS/cm to 12 mS/cm at 25° C. The present invention can improve the cycle performance and storage performance of the electrochemical device, in particular, improve the cycle performance and storage performance of the electrochemical device under high temperature and high voltage conditions while keeping the low temperature performance.