Lithium Secondary Battery Fluorinated Ether Electrolyte
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Solution Overview
Problem
Lithium secondary batteries face challenges in maintaining cycle characteristics due to side reactions between lithium metal and non-aqueous electrolytes, leading to decreased capacity and safety concerns, as lithium metal is precipitated and dissolved during charge and discharge, causing ununiform charge-discharge reactions and dendrite formation.
Innovation Solution
Incorporating a non-aqueous electrolyte with a fluorinated ether having a fluorination ratio of not more than 60%, which allows for uniform charge-discharge reactions by reducing interaction between lithium ions and the electrolyte, thereby suppressing dendrite formation and maintaining high solubility of lithium salts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium metal is used as an anode active material to achieve high capacity, then the battery capacity is improved, but side reactions occur between lithium metal and non-aqueous electrolyte leading to poor cycle characteristic
Solution Approach 1:
A fluorinated ether compound is introduced as an intermediary substance in the non-aqueous electrolyte. This compound mediates between the lithium metal anode and the main electrolyte solvent, forming a protective interface layer that prevents direct harmful interactions while allowing lithium ion transport, thus improving cycle characteristic without sacrificing capacity
Solution Approach 2:
The chemical composition parameters of the non-aqueous electrolyte are changed by incorporating fluorinated ether compounds with specific fluorination ratios (not more than 60%). This parameter change modifies the electrolyte's interaction properties with lithium metal, reducing side reactions and improving cycle stability while maintaining high capacity
2Device complexity
If conventional non-aqueous electrolyte is used to maintain simplicity, then the device complexity is low, but ununiform charge-discharge reactions occur leading to dendrite formation
Solution Approach 1:
The electrolyte composition is modified by adding fluorinated ether compounds with controlled fluorination ratios. This parameter change enhances the electrolyte's ability to facilitate uniform lithium ion distribution during charge-discharge, preventing dendrite formation while maintaining relative compositional simplicity
Solution Approach 2:
The fluorinated ether compound acts as an intermediary that promotes uniform charge-discharge reactions by mediating lithium ion transport at the electrode-electrolyte interface, preventing localized uneven reactions and dendrite formation without significantly complicating the overall electrolyte system
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 use of fluorinated ether in the non-aqueous electrolyte enhances the cycle characteristic of lithium secondary batteries by ensuring uniform charge-discharge reactions, reducing dendrite formation, and maintaining high capacity and safety, while preventing the decrease in cycle characteristics.
Implementation Method 1
the non-aqueous electrolyte contains a solvent and a lithium salt; the solvent includes a fluorinated ether
Implementation Method 2
a lithium metal is precipitated on a surface of the anode during charge of the lithium secondary battery
Implementation Method 3
the lithium metal is dissolved from the surface of the anode in the non-aqueous electrolyte during discharge of the lithium secondary battery
Data Source
AI summary
Provided is a lithium secondary battery comprising a cathode, an anode, and a non-aqueous electrolyte having lithium ion conductivity. A lithium metal is precipitated on a surface of the anode during charge of the lithium secondary battery. The lithium metal is dissolved from the surface of the anode in the non-aqueous electrolyte during discharge of the lithium secondary battery. The non-aqueous electrolyte contains a solvent and a lithium salt. The solvent includes a fluorinated ether. The fluorinated ether has a fluorination ratio of more than 0% and not more than 60%.