Secondary Battery Additive for Stable Electrode Interfacial Films
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Solution Overview
Problem
The instability of the interfacial film in secondary batteries leads to continuous dissolution of components, increased internal resistance, and reduced performance due to side reactions on the electrode surfaces, which affects the battery's cycling performance.
Innovation Solution
Incorporating an additive represented by Formula 1, which undergoes electrochemical polymerization to form a stable solid interfacial film on the electrodes, reducing side reactions and enhancing lithium ion dynamics, thereby improving the battery's cycling performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an interfacial film is formed on the positive and negative electrodes during first charge and discharge, then the battery can operate, but the film structure becomes unstable leading to continuous dissolution and generation of film components
Solution Approach 1:
The patent introduces a polyfunctional additive with specific molecular structure (containing M segment, R group, R′ group, and end groups) that changes the chemical composition parameters of the interfacial film. This additive modifies the film-forming reaction to produce a more stable solid interfacial film structure that resists continuous dissolution and regeneration, thereby improving both film stability and cycling performance
Solution Approach 2:
The patent creates a composite interfacial film structure by incorporating the polyfunctional additive into the film formation process. The additive acts as a building block that integrates with the natural film components (solvents and adjuvants) to form a composite structure with enhanced stability, reducing the continuous dissolution and generation of film components during battery operation
2Reliability
If the interfacial film components continuously dissolve and regenerate, then the battery can maintain operation, but this leads to continuous consumption of solvents and adjuvants in the electrolyte
Solution Approach 1:
The polyfunctional additive modifies the chemical parameters of the interfacial film to reduce its solubility and stability in the electrolyte. By changing the film composition through the additive's specific molecular structure (M segment, R group, R′ group, and end groups), the film becomes less prone to dissolution, thereby reducing continuous consumption of solvents and adjuvants from the electrolyte
3Power
If side reactions occur on the positive and negative electrode surfaces, then the battery can function, but internal resistance increases and performance deteriorates
Solution Approach 1:
The polyfunctional additive changes the chemical and physical parameters of the interfacial film to create a more stable and protective barrier on the electrode surfaces. This modified film structure suppresses harmful side reactions between the electrolyte and electrode materials, thereby reducing internal resistance increase and performance deterioration while maintaining necessary battery function
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 additive forms a high molecular weight polymer-rich interfacial film that stabilizes the electrode surfaces, reducing internal resistance and enhancing lithium ion conductivity, leading to improved cycling performance and capacity retention.
Implementation Method 1
The carbon-carbon double bond or carbon-carbon triple bond in the additive of the disclosure containing them undergoes electrochemical polymerization at low potential, and forms a stable and solid interfacial film on a surface of positive/negative electrode
Data Source
AI summary
The present disclosure provides a secondary battery, which includes an additive (a compound represented by Formula 1). The additive (compound represented by Formula 1) can be fully mixed with other components in the secondary battery due to its small molecular weight and short polymer segment. The additive (compound represented by Formula 1) is in a state of viscous liquid, semi-solid or solid at room temperature, which can fully contact each component and be immersed in internal pores. The additive of the present invention can form a film on the positive/negative electrode surface. The additive of the present disclosure can also participate in the film forming reaction of the positive and negative electrodes, and form a solid interfacial film structure with a certain molecular weight on the surfaces of the positive and negative electrodes.