High-Voltage Battery Electrolyte for Bulging-Resistant Cycling
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Solution Overview
Problem
High-voltage lithium-ion batteries face issues such as bulging and rapid cycle capacity decline at high temperatures, which complicates improving their energy density and lifespan.
Innovation Solution
An electrolyte comprising substituted or unsubstituted thiodilycolic anhydride and a trinitrile compound forms a stable SEI protective layer on electrodes, enhancing cycle performance at high temperatures and suppressing gas generation during discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the charging cut-off voltage of lithium-ion batteries is increased to improve energy density, then the energy density is improved, but the battery becomes prone to bulging and cycle capacity declines rapidly at high temperature
Solution Approach 1:
The patent introduces novel electrolyte additives (thiodiglycolic anhydride derivatives and trinitrile compounds) that change the chemical composition parameters of the electrolyte system. These additives modify the decomposition behavior at high voltage, enabling stable operation at 4.45V or higher charging cut-off voltages while preventing the bulging and capacity decline issues that plague conventional electrolyte systems.
Solution Approach 2:
The patent employs specific electrolyte additives as intermediary substances that mediate between the electrode materials and the bulk electrolyte. These additives (compounds of Formula I and Formula II/III) form protective interface layers that reconcile the high voltage requirements with the stability needs, acting as a buffer that prevents direct harmful interactions between the high-voltage electrodes and conventional electrolyte components.
2Use of energy by moving object
If the charging cut-off voltage is increased to enhance deintercalation of lithium from positive electrode materials, then the energy density is improved, but the battery gets prone to bulging
Solution Approach 1:
The patent applies preliminary action by having the electrolyte additives (thiodiglycolic anhydride and trinitrile compounds) pre-form protective films on the electrode surfaces before high-voltage operation begins. This preliminary protective layer prevents subsequent gas generation and swelling that would cause bulging, allowing the battery to safely operate at elevated charging cut-off voltages of 4.45V or higher.
3Use of energy by moving object
If high-voltage operation is implemented to improve energy density, then the energy density is improved, but cycle capacity declines rapidly at high temperature
Solution Approach 1:
The patent creates a composite electrolyte system by combining conventional electrolyte components with novel additive compounds (thiodiglycolic anhydride derivatives and trinitrile compounds). This composite electrolyte formulation synergistically combines the high-voltage stability provided by the additives with the ionic conductivity of conventional electrolytes, enabling sustained high-performance operation at elevated temperatures and extended cycle life.
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 significantly improves the high-temperature intermittent cycle performance and stability of lithium-ion batteries, allowing stable charging and discharging at high voltages while preventing battery bulging.
Implementation Method 1
The electrolyte can form a stable SEI protective layer on positive and negative electrodes
Data Source
AI summary
An electrolyte, including: a compound of Formula I, and at least one of a compound of Formula II or a compound of Formula III,R1, R2, R3 and R4 are each independently selected from hydrogen, fluoro, substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C2-C10 alkenyl, substituted or unsubstituted C2-C10 alkynyl, substituted or unsubstituted C6-C12 aryl, substituted or unsubstituted C1-C10 alkoxy, or substituted or unsubstituted C6-C12 aryloxy, wherein when substituted, the substituent is fluoro, cyano or C1-C10 alkyl; and a, d and f are each independently selected from an integer from 1 to 5, and b, c, e, g, h and i are each independently selected from an integer from 0 to 5.