Battery Electrolyte Additives for Stable SEI Film Formation
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Solution Overview
Problem
Secondary batteries face challenges in improving cycle performance and storage life due to deterioration of the solid electrolyte interphase (SEI) film, leading to reduced stability and lifespan.
Innovation Solution
An electrolyte solution containing specific additives, such as compounds represented by formula (I) and (II), which undergo copolymerization to form polycarbonate and polysulfate/polysulfonate polymers, enhancing the interface film's toughness and compactness, thereby improving cycle stability and storage life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolyte solutions are used, then the battery can operate initially, but the interface film deteriorates over time leading to poor cycle performance and short storage life
Solution Approach 1:
The patent applies preliminary action by introducing specific additive compounds (formula I and formula II) that proactively form a stable interface film during the formation stage of the battery. These additives undergo copolymerization reactions to create a robust solid electrolyte interphase film before operational degradation can occur, preventing subsequent deterioration rather than merely responding to it. This preliminary protective action ensures both cycle performance and storage life are maintained from the outset.
Solution Approach 2:
The patent employs composite materials principle by creating a copolymer interface film through the copolymerization of two different additive compounds (formula I and formula II). This composite film structure combines the beneficial properties of both polymer types, resulting in an interface film that is more resistant to deterioration than single-polymer films. The composite nature of the film provides enhanced stability for both cycle operation and long-term storage.
2Reliability
If the interface film is made more compact to prevent co-intercalation, then storage life improves, but the film may become too rigid affecting ion transport
Solution Approach 1:
The patent applies local quality principle by creating an interface film with spatially varying properties through copolymerization. The film contains different polymer segments (from compounds I and II) distributed throughout its structure, creating local regions with different characteristics. This allows the film to be compact and protective in some areas while maintaining sufficient ion transport channels in others, balancing storage life improvement with ion transport efficiency.
Solution Approach 2:
The patent uses parameter changes by controlling the copolymerization process and additive concentrations to optimize the interface film's physical and chemical parameters. By adjusting the ratio and amounts of compounds (I) and (II), the film's density, crosslinking degree, and porosity can be tuned to achieve the optimal balance between compactness for storage stability and permeability for ion transport during cycling.
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 solution effectively prolongs battery life by maintaining a stable interface film, reducing decay rates, and preventing co-intercalation of molecules, thus enhancing cycle stability and storage life.
Implementation Method 1
the first additive undergoes a copolymerization reaction in the electrolyte solution and participates in film forming at the formation stage of the battery. A formed copolymer has advantages of a polycarbonate polymer and a polysulfate polymer and/or a polysulfonate polymer
Implementation Method 2
can continuously provide a film-forming substance for a battery to repair an interface film between the electrode plate and the electrolyte solution
Implementation Method 3
SO2 and CO2 can change the bond breaking and forming form of the first additive in the formation stage, and inhibit the first additive from forming SO2 and CO2 in the formation stage, but form more inorganic-organic compact interface films containing sulfate, carbonate, and polycarbonate-polysulfate/polysulfonate
Data Source
AI summary
An electrolyte solution, a battery containing the same, and a power consuming apparatus. The electrolyte solution includes: a first additive, where the first additive includes at least one of compounds represented by formula (I) and formula (II); and a second additive, where the second additive includes at least one of SO2 and CO2.