Polymerizable Aromatic Electrolyte for High-Voltage Lithium Batteries
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Solution Overview
Problem
Conventional lithium rechargeable batteries face issues with voltage resistance and thermal stability due to electrolyte decomposition at high temperatures, especially when charged beyond 4.2 V, which affects their cycle life and energy density.
Innovation Solution
A non-aqueous electrolyte is developed that includes polymerizable aromatic compounds and fluorinated organic compounds, forming a passivation film on the positive electrode to prevent decomposition, and additives for the negative electrode to enhance film protection, maintaining stability up to 4.5 V.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the charge voltage is increased to over 4.2 V to improve energy density, then the energy density and average operating voltage are improved, but the non-aqueous electrolyte decomposes due to increased positive electrode potential
Solution Approach 1:
The patent applies preliminary action by introducing a polymerizable aromatic compound that automatically polymerizes on the positive electrode surface during initial charging cycles to form a protective passivation film before the electrolyte can decompose. This pre-formed film prevents subsequent electrolyte decomposition at high voltages, enabling stable operation above 4.2 V while maintaining energy density improvements.
2Reliability
If a sulfurous acid ester and halogenated alkyl group are used to achieve high voltage resistance, then the voltage resistance of the electrolyte is improved, but the lithium ion conductivity is drastically reduced
Solution Approach 1:
The patent uses a polymerizable aromatic compound as an intermediary substance that forms a passivation film on the positive electrode surface. This film acts as a mediator that allows high voltage resistance without requiring the use of sulfurous acid esters or halogenated alkyl groups in the bulk electrolyte, thereby maintaining lithium ion conductivity while achieving the desired voltage resistance.
3Temperature
If the non-aqueous electrolyte is used at high temperatures, then the battery can operate in high temperature environments, but the cycle and battery characteristics deteriorate due to electrolyte decomposition
Solution Approach 1:
The polymerizable aromatic compound performs preliminary action by forming a stable passivation film on the positive electrode surface during initial charging cycles. This pre-formed protective layer prevents electrolyte decomposition at high temperatures during subsequent operation, thereby maintaining cycle characteristics and battery performance in high temperature environments without limiting the operating temperature range.
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 provides improved voltage resistance and thermal stability, reducing thermal runaway and maintaining high capacity and efficiency in lithium rechargeable batteries even at high temperatures.
Implementation Method 1
The aromatic compound in the non-aqueous electrolyte is polymerized on the surface of the positive electrode during initial charging to form a passivation film
Implementation Method 2
The passivation film prevents direct contact between the positive electrode and the non-aqueous electrolyte. Accordingly, decomposition of the non-aqueous electrolyte due to oxidation is prevented
Implementation Method 3
The fluorinated organic compound does not decompose due to the oxidation of the positive electrode of the lithium rechargeable battery
Data Source
AI summary
A non-aqueous electrolyte having improved lithium ion conductivity and excellent voltage resistance is provided. A lithium rechargeable battery and a rechargeable battery system including the inventive non-aqueous electrolyte is also provided. The non-aqueous electrolyte includes at least one aromatic compound which is polymerizable at a working electrode potential of 4.2 to 4.5 V when a lithium metal is used as a counter electrode and platinum is used as a working electrode.