Isocyanate Battery Electrolyte With LiFSI for Stable Interface Films
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Solution Overview
Problem
Secondary batteries face challenges in cycle performance and storage life, with issues such as water absorption leading to degradation of the electrolytic solution, increased internal resistance, corrosion of electrode interface films, and risks of thermal runaway.
Innovation Solution
An electrolytic solution comprising an isocyanate compound and lithium bis(fluorosulfonyl)imide, with controlled weight ratios, to improve acid-binding capacity, thermal stability, and electrical conductivity, while minimizing corrosion and thermal runaway risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If isocyanate compound is added to improve acid-binding capacity and thermal stability, then cycle performance and storage life are improved, but film-forming impedance increases and kinetics performance deteriorates
Solution Approach 1:
Lithium bis(fluorosulfonyl)imide acts as an intermediary substance that mediates between the isocyanate compound and the electrode interface film. It forms a stable protective film that prevents the isocyanate compound from excessively increasing film-forming impedance, thereby maintaining kinetics performance while preserving the acid-binding and thermal stability benefits
Solution Approach 2:
The patent optimizes the concentration parameters of both isocyanate compound and lithium bis(fluorosulfonyl)imide to achieve the best balance. By carefully controlling the dosage of each component, the film-forming impedance is kept within acceptable ranges while maintaining improved cycle performance and storage life
2Productivity
If lithium bis(fluorosulfonyl)imide is increased to improve electrical conductivity and kinetics performance, then film-forming impedance decreases, but corrosion risk and thermal runaway risk increase
Solution Approach 1:
The isocyanate compound serves as a protective intermediary that forms a stable interface film between lithium bis(fluorosulfonyl)imide and the aluminum foil current collector. This film prevents direct contact and corrosion reactions, enabling higher concentrations of lithium bis(fluorosulfonyl)imide to be used safely for improved kinetics performance
Solution Approach 2:
The isocyanate compound performs preliminary protection by forming a protective film on the electrode interface before lithium bis(fluorosulfonyl)imide can cause corrosion or thermal runaway. This preliminary anti-action prevents harmful effects while allowing the benefits of high electrical conductivity to be realized
3Stability of the object's composition
If water is present in the electrolytic solution, then acid substances are generated leading to electrolyte degradation and internal resistance increase, but water also enables lithium salt dissociation
Solution Approach 1:
The isocyanate compound converts the harmful effect of water into a beneficial one by acting as an acid-binding agent. It captures the acid substances generated from water-lithium salt reactions, preventing electrolyte degradation and internal resistance increase, while still allowing water to facilitate lithium salt dissociation
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 enhances cycle performance, prolongs storage life, and reduces the risk of thermal runaway by balancing the effects of the isocyanate compound and lithium bis(fluorosulfonyl)imide, maintaining kinetics performance and forming stable electrode interface films.
Implementation Method 1
The isocyanate compound has a good acid-binding capacity, which can reduce the influence of water on the performance of the battery
Implementation Method 2
the isocyanate compound may participate in the formation of the electrode interface film, which can improve the thermal stability of the electrode interface film
Implementation Method 3
the lithium bis(fluorosulfonyl)imide is easy to dissociate into lithium ions in the electrolytic solution, which can increase the electrical conductivity of the battery
Implementation Method 4
water adsorbed by the electrode material may diffuse into the electrolytic solution and react with the lithium salt in the electrolytic solution to generate an acid substance
Data Source
AI summary
An electrolyte solution, a battery cell comprising same, a battery and an electric device. The electrolyte solution comprises: a first additive, which comprises an isocyanate compound as represented by formula (I), wherein R comprises at least one of a hydrogen atom, a halogen atom, a nitrogen-containing group, an oxygen-containing group, a sulfur-containing group, a phosphorus-containing group, an alkyl group, a cycloalkyl group, a phenyl group, an aryl group, a halophenyl group, and an alkyl, cycloalkyl, phenyl, aryl or halophenyl group containing at least one isocyanate radical, and the value of n is any natural number of 0-8; and a lithium salt, which comprises lithium difluorosulfonimide, the weight content of the lithium difluorosulfonimide in the lithium salt being 30%-85% based on the total weight of the lithium salt.