Silicon Anode SEI Film Stabilization via Dual Additives
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Solution Overview
Problem
Rechargeable lithium batteries face challenges with cycle-life characteristics, particularly with silicon-based negative active materials, which experience capacity loss due to volume expansion and instability of the solid electrolyte interphase (SEI) film, leading to reduced performance and high temperature limitations.
Innovation Solution
Incorporating an ethylene carbonate-based compound and a pyridine-based compound as additives in the electrolyte, along with a silicon-based negative active material, to form a stable SEI film with high binding energy, thereby improving cycle-life characteristics and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based material is used as negative active material to increase capacity, then battery capacity is improved, but volume expansion occurs during cycling causing capacity loss and reduced cycle life
Solution Approach 1:
The patent applies preliminary action by introducing specific electrolyte additives (ethylene carbonate-based compound and pyridine-based compound) before cycling begins. These additives pre-form a stable SEI film on the silicon-based negative electrode surface during initial cycles, creating a protective layer that prevents subsequent volume expansion damage and maintains capacity stability throughout the battery's operational life
Solution Approach 2:
The patent uses the SEI film formed by ethylene carbonate-based and pyridine-based additives as an intermediary between the silicon-based negative active material and the electrolyte. This intermediate layer acts as a protective barrier that mediates the interaction between silicon and electrolyte, preventing direct harmful reactions while allowing lithium ion transport, thus resolving the contradiction between high capacity and cycle stability
2Quantity of substance
If silicon-based material is used as negative active material to increase capacity, then battery capacity is improved, but SEI film instability occurs leading to capacity loss
Solution Approach 1:
The patent applies parameter changes by modifying the electrolyte composition parameters - specifically adding ethylene carbonate-based compound (0.1-20 parts by weight) and pyridine-based compound (0.1-3 parts by weight) per 100 parts by weight of non-aqueous organic solvent. These compositional changes alter the SEI film formation parameters, creating a more stable film that maintains reliability while supporting high capacity silicon-based electrodes
3Device complexity
If conventional electrolyte is used to maintain simplicity, then device complexity is low, but high temperature performance is poor
Solution Approach 1:
The patent applies composite materials by creating a composite electrolyte system that combines non-aqueous organic solvent with specific additives (ethylene carbonate-based compound and pyridine-based compound). This composite electrolyte formulation enhances high-temperature stability and performance while maintaining relatively simple device structure, resolving the contradiction between complexity and temperature performance
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 proposed solution enhances the cycle-life and high-temperature performance of rechargeable lithium batteries by stabilizing the SEI film and reducing thickness variations, maintaining high capacity and improving overall battery stability.
Implementation Method 1
which experience capacity loss due to volume expansion and instability of the solid electrolyte interphase (SEI) film
Implementation Method 2
The positive and negative electrodes may intercalate and deintercalate lithium ions and produce electrical energy through oxidation and reduction reactions
Implementation Method 3
A rechargeable lithium battery may include positive and negative electrodes that may include a material that can reversibly intercalate/deintercalate lithium ions
Implementation Method 4
The positive and negative electrodes may intercalate and deintercalate lithium ions and produce electrical energy through oxidation and reduction reactions
Data Source
AI summary
Disclosed is a rechargeable lithium battery including a positive electrode; a negative electrode including a negative active material, the negative active material including a silicon-based material; and an electrolyte solution including a lithium salt, a non-aqueous organic solvent, and an additive. The additive includes an ethylene carbonate-based compound represented by Chemical Formula 1 and a pyridine-based compound represented by Chemical Formula 2:R11, R12 and R1 to R5 are each independently hydrogen, a halogen, a substituted or unsubstituted C1 to C20 alkyl group, or a C1 to C20 haloalkyl group; at least one of R11 and R12 is a halogen; and at least one of R1 to R5 is a halogen.