Li-Ion Battery Electrolyte Tuning to Mitigate Lithium Plating
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Solution Overview
Problem
Lithium plating in lithium-ion batteries leads to reduced cycling and safety performance, exacerbated by burrs at the edge of the negative electrode plate increasing the risk of short circuits.
Innovation Solution
Incorporating a fluorinated solvent in the electrolyte to form a LiF-rich SEI film with high toughness, controlling the weight-based content and ratio of electrode widths to stabilize interfaces and mitigate lithium plating, while enhancing lithium ion diffusion and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fluorinated solvent is added to the electrolyte to improve lithium ion solubility and stability, then lithium plating is mitigated and cycling performance is improved, but burrs at the edge of the negative electrode plate increase the risk of short circuits
Solution Approach 1:
The patent applies local quality by forming an SEI film with specific composition and structure at different locations. The SEI film is enriched with LiF at the negative electrode interface and has enhanced properties at the edge regions where burrs exist, providing localized protection where it is most needed while maintaining overall battery performance
Solution Approach 2:
The SEI film acts as an intermediary layer between the electrolyte and the electrode surfaces. This intermediate layer, particularly enriched with LiF at strategic locations, mediates the interaction between the fluorinated solvent and the electrodes, preventing direct harmful effects while maintaining beneficial lithium ion transport
2Reliability
If the content of fluorinated solvent is increased to form a more protective SEI film, then safety is improved, but lithium ion diffusion speed may be reduced
Solution Approach 1:
The patent optimizes the concentration parameter of the fluorinated solvent in the electrolyte to achieve the desired balance. By controlling the solvent content and the ratio of electrode widths, the system forms an SEI film with appropriate thickness and composition that provides protection while maintaining ion transport efficiency
Solution Approach 2:
The SEI film forms a composite structure with LiF enrichment at the interface. This composite material combines the protective properties of LiF with the ion-conducting properties of the electrolyte components, achieving both safety and 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 SEI film improves battery safety and cycling performance by reducing short circuit risks and maintaining high lithium ion transport rates, ensuring stable cycling and safety.
Implementation Method 1
a Life-rich SEI film having a relatively small thickness and a relatively high toughness can be formed by the fluorinated solvent on the surfaces of the positive and negative electrodes
Implementation Method 2
the stability of the interfaces between the positive and negative electrode plates and the electrolyte can be improved, reducing the concentration polarization and electrochemical polarization of the electrolyte during lithium intercalation/deintercalation
Implementation Method 3
increasing the transport rate of lithium ions in the electrolyte, and mitigating lithium plating
Data Source
AI summary
A lithium-ion battery includes an electrolyte, a negative electrode plate and a positive electrode plate. The electrolyte includes a fluorinated solvent; and with a content of the fluorinated solvent being f wt % based on a total weight of the electrolyte, and a ratio of a width of the negative electrode plate to a width of the positive electrode plate being g, the lithium-ion battery satisfies a following relation: 2≤f/g≤30.