Pyridine-SO3 Complex Electrolyte for High Voltage Battery Stability
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Solution Overview
Problem
Lithium ion batteries face challenges in maintaining electrochemical properties such as long cycle life, storage stability, and rate capability, especially at elevated temperatures and high working voltages, due to decomposition reactions that accelerate at elevated temperatures, leading to capacity fading and increased internal resistance.
Innovation Solution
An electrolyte composition containing at least one aprotic organic solvent, one conducting salt, and one pyridine-SO3 complex, which acts as a film-forming additive to enhance cycling performance and stability at elevated temperatures, even up to a cut-off voltage of 4.8 V.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the battery operates at elevated temperatures, then the reaction rate increases and power output improves, but decomposition reactions accelerate leading to capacity fading and increased internal resistance
Solution Approach 1:
The patent introduces sulfur trioxide pyridine complex as an intermediary substance that mediates between the electrode and electrolyte. This complex forms a protective interface layer that prevents direct harmful interactions while allowing beneficial electrochemical reactions to proceed, thus stabilizing electrochemical properties at elevated temperatures without sacrificing reaction rate
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte by adding sulfur trioxide pyridine complex at specific concentrations (0.1-5 wt%). This parameter change alters the chemical environment at the electrode interface, creating conditions that suppress decomposition reactions while maintaining efficient charge transfer, thereby resolving the contradiction between reaction rate and stability
2Quantity of substance
If the cut-off voltage is increased to improve energy density, then the battery capacity increases, but decomposition reactions accelerate leading to reduced cycle life
Solution Approach 1:
The sulfur trioxide pyridine complex performs preliminary protective action by forming a stable interface layer on the electrode surface before high-voltage operation begins. This pre-formed protective layer prevents subsequent decomposition reactions that would otherwise occur at high voltages, enabling the battery to operate at increased cut-off voltages (up to 4.8V) without sacrificing cycle life
Solution Approach 2:
The patent converts the potentially harmful effect of high voltage into a beneficial outcome by using sulfur trioxide pyridine complex to stabilize the electrode interface. The complex enables the battery to utilize higher cut-off voltages for increased capacity while the same interface stabilization prevents the decomposition reactions that would normally reduce cycle life at these elevated voltages
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 electrolyte composition with pyridine-SO3 complex demonstrates improved cycling retention and coulombic efficiency, maintaining good electrochemical properties and extending the battery's lifespan by forming a protective film on electrodes, thus preventing direct contact with the electrolyte and reducing degradation.
Implementation Method 1
film forming additives which react during first charge/discharge cycle on the electrode surface thereby forming a film on the electrode
Implementation Method 2
organic carbonates, ethers, esters and ionic liquids are used as sufficiently polar solvents for solvating the conducting salt(s)
Data Source
AI summary
An electrolyte composition including (i) at least one aprotic organic solvent; (ii) at least one conducting salt; (iii) at least one pyridine-SO3 complex of formula (I)wherein R is selected independently at each occurrence from F, C1 to C10 alkyl, C2 to C10 alkenyl, and C2 to C10 alkynyl, wherein alkyl, alkenyl, and alkynyl may be substituted by one or more substituents selected from F and CN; and n is an integer selected from 1, 2, 3, 4, and 5; and (vi) optionally one or more additives; and its use in electrochemical cells.