Fluorinated Electrolyte for 5V Spinel Cathode Stability
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Solution Overview
Problem
Lithium ion batteries with 5 V spinel cathodes face suboptimal cycling performance at high temperatures due to intrinsic instability of traditional carbonate electrolytes and accelerated decomposition reactions.
Innovation Solution
A lithium ion battery design featuring a manganese cathode with a spinel structure and a nonaqueous electrolyte composition including a fluorinated acyclic carboxylic acid ester, which provides improved ion conductivity and stability at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional carbonate electrolyte is used in 5V spinel cathode battery, then ion conductivity is maintained, but cycling performance deteriorates at high temperature due to electrolyte instability and decomposition
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing fluorinated cyclic carbonate (FCC) and fluorinated chain carbonate (FChC) components with specific fluorine substitution patterns. This parameter change transforms the electrolyte from traditional carbonate to fluorinated carbonate composition, which maintains ion conductivity while providing superior thermal and chemical stability at high operating temperatures, thereby resolving the contradiction between cycling performance and electrolyte stability
Solution Approach 2:
The patent creates a composite electrolyte system by combining fluorinated cyclic carbonate and fluorinated chain carbonate components in specific ratios. This composite approach leverages the complementary properties of different fluorinated compounds to achieve both high ion conductivity and enhanced stability, solving the contradiction where single-component traditional electrolytes fail to provide adequate high-temperature cycling performance
2Use of energy by moving object
If operating voltage is increased to 5V to improve energy density, then energy density improves, but cathode material stability deteriorates due to lattice strain and corrosion reactions
Solution Approach 1:
The fluorinated electrolyte composition acts as an intermediary protective layer between the 5V cathode material and the harsh operating environment. The electrolyte forms stable interface films that mediate the interaction between the high-voltage cathode and decomposition reactions, reducing direct corrosion while maintaining the high operating voltage necessary for energy density, thus resolving the contradiction between energy density and cathode stability
Solution Approach 2:
The patent changes the electrochemical window parameters of the electrolyte through fluorination, extending the stable voltage range to accommodate 5V operation. This parameter change in the electrolyte's electrochemical stability allows the cathode to operate at higher voltages without triggering decomposition reactions, enabling high energy density while maintaining cathode material stability
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 battery exhibits enhanced cycling performance and capacity retention at elevated temperatures, outperforming conventional lithium ion batteries in high-temperature applications.
Implementation Method 1
a nonaqueous electrolyte composition providing an ionically conductive pathway between the anode and the cathode
Implementation Method 2
an anode and a cathode disposed in the housing and in conductive contact with one another
Data Source
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AI summary
A lithium ion battery that has a spinel cathode and a nonaqueous electrolyte comprising a fluorinated acyclic carboxylic acid ester and/or a fluorinated acyclic carbonate solvent is described. The lithium ion battery operates at a high voltage (i.e. up to about 5 V) and has improved cycling performance at high temperature.