Dual-Additive Battery Electrolyte for High-Voltage Cycle-Life
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Solution Overview
Problem
Rechargeable lithium batteries experience side reactions such as gas generation and increased interface resistance due to transition metal ions eluting from the positive electrode into the electrolyte, which degrade the battery's cycle-life, especially under high temperature and high voltage conditions.
Innovation Solution
An electrolyte comprising a non-aqueous organic solvent, lithium salt, a phosphite-based first additive, and phosphate-based second additive forms a robust positive electrode protective layer that suppresses transition metal ion elution, facilitating lithium ion movement and reducing side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the rechargeable lithium battery is driven at high temperature and charged at high voltage, then the energy density and charging rate are improved, but transition metal ions elute from the positive electrode into the electrolyte causing side reactions that reduce cycle-life
Solution Approach 1:
The patent introduces a mediator substance (lithium fluoroacetate or lithium difluoroacetate) that acts as an intermediary between the positive electrode and electrolyte. This mediator forms a protective interface layer that prevents direct contact and harmful interactions, thereby suppressing transition metal ion elution while allowing the battery to operate at high temperature and high voltage for improved energy density
Solution Approach 2:
The patent applies preliminary anti-action by pre-forming a protective film on the positive electrode surface using the lithium fluoroacetate or lithium difluoroacetate additive before harmful elution can occur. This preliminary protective layer counteracts the harmful effects of high temperature and high voltage operation, preventing transition metal ion dissolution into the electrolyte and maintaining cycle-life reliability
2Productivity
If the rechargeable lithium battery is driven at high temperature and charged at high voltage, then the charging rate is improved, but gas generation and interface resistance increase at the negative electrode-electrolyte interface
Solution Approach 1:
The lithium fluoroacetate or lithium difluoroacetate acts as an intermediary that forms a protective interface layer on the positive electrode, preventing transition metal ion elution into the electrolyte. This intermediary layer eliminates the source of harmful effects (eluted ions) that would otherwise cause gas generation and increased interface resistance at the negative electrode, enabling high charging rates without these harmful byproducts
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 effectively reduces gas generation and interface resistance, enhancing the cycle-life of rechargeable lithium batteries across various temperatures and charging voltages.
Implementation Method 1
forms a robust positive electrode protective layer that suppresses transition metal ion elution
Implementation Method 2
facilitating lithium ion movement
Data Source
AI summary
An electrolyte for a rechargeable lithium battery includes a non-aqueous organic solvent; a lithium salt; a first additive represented by represented by Chemical Formula 1; and a second additive represented by represented by Chemical Formula 2:In addition, a rechargeable lithium battery including the electrolyte is also disclosed.