Li-Ion Battery Electrolyte Additives for Fast Charging Cycle Stability
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Solution Overview
Problem
Lithium-ion secondary batteries face a challenge in improving charging capability while maintaining cycling stability, as enhancing rate performance often compromises cycling stability.
Innovation Solution
A lithium-ion secondary battery design incorporating specific additives and controlled particle sizes for the negative electrode active material forms a moderately thick and uniform SEI protective layer, enhancing interfacial stability and reducing uneven lithium intercalation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the rate performance is improved, then the charging capability is enhanced, but the cycling stability decreases
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing specific additives (first additive from formulas I-IV and second additive from VC, PS, or LiPF2O2) with controlled mass percentages (0.05≤W1≤0.8 and 0.01≤W2≤4.1). This modifies the SEI layer properties to achieve both high rate performance and cycling stability
Solution Approach 2:
The patent creates a composite SEI protective layer through the synergistic interaction of multiple additives (first additive and second additive) on the negative electrode surface. This composite structure provides both the conductivity needed for fast charging and the stability required for long cycle life
2Reliability
If a thick protective layer is formed on the negative electrode, then the cycling stability is improved, but the charging capability decreases
Solution Approach 1:
The patent precisely controls the thickness parameter of the SEI layer by adjusting additive concentrations (0.05≤W1≤0.8 and 0.01≤W2≤4.1), forming a moderately thick protective layer that balances protection and ion transport, avoiding both thin unstable layers and excessively thick blocking layers
Solution Approach 2:
The patent creates a uniformly distributed moderately thick protective layer across the entire negative electrode surface through controlled additive deposition, ensuring consistent protection and ion transport properties throughout the electrode structure
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 effectively prolongs the lifecycle of the negative electrode active material, ensuring cycling stability and improving charging capability by mitigating excessive lithium intercalation issues.
Implementation Method 1
The first additive and the second additive of this application can form stable interfaces on the surfaces of the positive electrode active material and the negative electrode active material... a moderately thick and uniform protective layer having similar SEI (Solid electrolyte Interface, Solid electrolyte Interface) components can be formed on a surface of the negative electrode active material during a battery formation process
Implementation Method 2
The uniform thickness of the SEI protective layer and the uniform and moderate particle size of the negative electrode active material can reduce the uneven lithium intercalation at different positions of the negative electrode plate during high-rate charging of the lithium-ion secondary battery
Data Source
AI summary
A lithium-ion secondary battery includes an electrolyte, a positive electrode plate, a separator, and a negative electrode plate. The electrolyte includes a first additive and a second additive, based on a mass of the electrolyte, W1% is a mass percentages of the first additive and W2% is a mass percentages of the second additive, 0.05≤W1≤0.8 and 0.01≤W2≤4.1. The negative electrode plate includes a negative electrode current collector and a negative electrode material layer containing a negative electrode active material.