Non-Aqueous Electrolyte Additives for High-Voltage Lithium Batteries
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Solution Overview
Problem
Conventional lithium-ion batteries face challenges in achieving high energy density and fast charging while maintaining high-temperature and cycle performance due to electrolyte decomposition at high voltages, and the increasing restrictions on sulfur-containing compounds.
Innovation Solution
A non-aqueous electrolyte comprising organic solvents, electrolyte lithium salts, and specific additives such as pyridine boron trifluoride, fluoroethylene carbonate, and hexane-1,3,6-tricarbonitrile, which inhibit electrolyte decomposition and enhance high-temperature and cycle performance even at high voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the charge cut-off voltage is increased to 4.4V or above to improve energy density, then the energy density is improved, but the electrolyte undergoes oxidation and decomposition causing capacity decrease and increased internal resistance
Solution Approach 1:
The patent introduces pyridine boron trifluoride as an intermediary substance that mediates between the high-voltage cathode material and the electrolyte. This additive forms a stable interface layer that prevents direct harmful interactions, allowing the battery to operate at 4.4V or above without severe electrolyte decomposition. The intermediary layer acts as a protective buffer that maintains cycle performance while enabling high energy density operation.
Solution Approach 2:
The patent changes the chemical composition parameters of the electrolyte by incorporating specific additives (pyridine boron trifluoride, fluoroethylene carbonate, and hexane-1,3,6-tricarbonitrile) in optimized proportions. This parameter change modifies the electrolyte's stability characteristics, raising its oxidation resistance threshold to accommodate 4.4V operating conditions without sacrificing cycle life.
2Reliability
If sulfur-containing compounds are used to improve electrolyte performance, then the electrochemical performance is improved, but the compounds may be restricted due to SVHC list expansion
Solution Approach 1:
The patent extracts and eliminates sulfur-containing compounds from the electrolyte formulation, removing the problematic substance entirely while maintaining performance through alternative additives. This extraction approach ensures regulatory compliance with expanding SVHC restrictions while preserving electrochemical performance through the use of pyridine boron trifluoride and other non-sulfur additives.
Solution Approach 2:
The patent changes the chemical composition by substituting sulfur-containing compounds with alternative substances having different chemical properties. The new formulation uses pyridine boron trifluoride, fluoroethylene carbonate, and hexane-1,3,6-tricarbonitrile, which provide equivalent or superior electrochemical performance without the regulatory restrictions associated with sulfur compounds.
3Ease of manufacture
If conventional electrolyte formulations are used to simplify manufacturing, then the ease of manufacture is improved, but the high-temperature performance deteriorates at high voltage
Solution Approach 1:
The patent creates a composite electrolyte formulation combining multiple components (pyridine boron trifluoride, fluoroethylene carbonate, hexane-1,3,6-tricarbonitrile) that work synergistically to provide high-temperature stability at high voltage. This composite approach maintains manufacturing simplicity while dramatically improving thermal performance compared to conventional single-component or simple mixture electrolytes.
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 solution improves high-temperature performance and reduces impedance, enhancing energy density and cycle performance, and enhances the safety and electrochemical performance of lithium batteries.
Implementation Method 1
When the charge cut-off voltage is higher than 4.4V, the electrolyte will undergo oxidation and decomposition on the surface of the battery. This process causes the battery capacity to decrease sharply. In the meanwhile, the products of oxidation and decomposition cover the surface of the electrode material
Implementation Method 2
the products of oxidation and decomposition cover the surface of the electrode material, causing the battery to have an increased internal resistance
Data Source
AI summary
Embodiments described herein are directed to an electrolyte solution and a lithium-ion secondary battery. The electrolyte solution includes an organic solvent, an electrolyte salt and an additive, wherein the additive includes pyridine boron trifluoride, fluoroethylene carbonate and 1,3,6-hexanetricarbonitrile. The mass percentage content of the pyridine boron trifluoride in the electrolyte solution is 0.1-5%; the mass percentage content of the fluoroethylene carbonate in the electrolyte solution is 0.1-8%; and the mass percentage content of the 1,3,6-hexanetricarbonitrile in the electrolyte solution is 0.1-5%. By means of the synergistic effect of the different types of additives mentioned above, the high-temperature performance and the normal-temperature performance of a high-voltage lithium-ion battery are improved; moreover, the use of sulfur-containing substances can be reduced or even avoided.