Secondary Battery Interface Passivation for Cycle and Storage Stability
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Solution Overview
Problem
Current secondary batteries for electric vehicles and hybrid electric vehicles face challenges in achieving a balance between cycle performance and storage performance, with existing methods failing to effectively improve cycle life and storage capacity due to issues with the solid electrolyte interface (SEI) membrane stability and volume changes in electrode materials.
Innovation Solution
Incorporating an interface passivator, such as compounds containing lithium, sodium, beryllium, magnesium, potassium, calcium, aluminum, or germanium, into the negative and positive electrode material layers and electrolytic solution to form a ternary passivation layer on the surface of the negative electrode, which reduces battery impedance and enhances cycle life and storage performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrode materials and electrolytes are used, then the battery can operate with basic performance, but the cycle life and storage performance remain insufficient
Solution Approach 1:
The interface passivator is incorporated into the electrode materials and electrolyte before battery assembly and operation. During the first charging cycle, the passivator pre-forms a stable ternary passivation layer (A-D-E layer) on the negative electrode surface, which prevents subsequent degradation reactions and establishes long-term stability before the battery enters service
Solution Approach 2:
The interface passivator acts as an intermediary substance that mediates between the negative electrode material and the electrolyte. It forms a ternary passivation layer containing elements A, D, and E, where A is an alkali metal, D is silicon or carbon, and E is the passivator element, creating a stable interface that reconciles the conflicting requirements for cycle life and storage performance
2Productivity
If the battery operates for multiple cycles, then energy storage and release occur, but the impedance increases and performance degrades
Solution Approach 1:
The interface passivator provides preliminary anti-action by forming a protective ternary passivation layer before harmful degradation reactions can occur. This pre-formed layer prevents impedance-increasing side reactions between the electrode and electrolyte during cycling, maintaining low impedance throughout the battery's operational life
Solution Approach 2:
The invention changes the chemical composition parameters of the electrode interface by incorporating the interface passivator with specific elements (A, D, E). This compositional change transforms the interface properties, creating a passivation layer with optimized electrical resistance and chemical stability that maintains performance during cycling
3Duration of action of stationary object
If the battery is stored for extended periods, then energy is preserved, but storage performance deteriorates due to interface instability
Solution Approach 1:
The interface passivator performs preliminary action by forming a stable passivation layer during initial charging cycles before storage begins. This pre-established protective layer prevents degradation reactions during extended storage, maintaining interface stability and storage performance over time
Solution Approach 2:
The interface passivator acts as a sacrificial component that forms a stable passivation layer during initial cycles. This layer effectively 'disposes of' the reactive interface components that would otherwise cause degradation during storage, protecting the main electrode materials from deterioration
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 ternary passivation layer stabilizes the electrode interface, accommodates volume changes, and improves overall battery performance by reducing internal resistance and increasing capacity retention rate, especially after multiple cycles and high-temperature storage.
Implementation Method 1
The A-D-E ternary layer is formed by a reaction of the interface passivator on the surface of the negative electrode material layer during at least one charging of the secondary battery
Implementation Method 2
the interface passivator is provided such that the secondary battery can has a beneficial ternary layer on a surface of the negative electrode material layer
Data Source
AI summary
A secondary battery includes a negative electrode plate including a negative electrode material layer, a positive electrode plate including a positive electrode material layer, and an electrolytic solution. At least one of the negative electrode material layer, the positive electrode material layer and the electrolytic solution contains an interface passivator, and the interface passivator is a compound containing an element E selected from lithium, sodium, beryllium, magnesium, potassium, calcium, aluminum, gallium, or germanium.