Non-Aqueous Electrolyte Additives for 4.5 V Lithium Battery Stability
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Solution Overview
Problem
Conventional lithium-ion batteries face challenges in maintaining high-temperature performance and discharge performance when voltage is increased above 4.4 V, leading to decreased safety and electrochemical performance, especially with the decline in high-temperature storage and cycling performance without the use of sulfur-containing additives.
Innovation Solution
A non-aqueous electrolyte comprising a lithium salt, organic solvent, and specific additives such as hepta-1,6-diyne-4-one and boron-containing lithium salts, which enhance high-temperature and discharge performance at high voltages, ensuring safety and electrochemical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the charge cutoff voltage is increased above 4.4 V to increase energy density, then the energy density is improved, but the electrolyte undergoes oxidative decomposition leading to sharp capacity decline and increased internal resistance
Solution Approach 1:
The patent introduces a mediator substance (fluoroethylene carbonate or its derivatives) into the electrolyte system. This intermediary component reacts preferentially with the electrode surface to form a protective film that prevents direct contact between the high-voltage electrode and the bulk electrolyte, thereby enabling stable operation above 4.4 V without oxidative decomposition
Solution Approach 2:
The patent changes the chemical composition parameters of the electrolyte by incorporating specific fluorinated cyclic carbonate compounds at controlled concentrations (0.1-5 wt%). This parameter modification alters the electrochemical window and stability characteristics of the electrolyte, enabling it to withstand higher voltages without decomposition
2Object-affected harmful factors
If sulfur-containing additives are excluded to meet SVHC regulations, then the environmental compliance is improved, but the high-temperature performance and discharge performance above 4.5 V deteriorate
Solution Approach 1:
The patent substitutes sulfur-containing compounds with fluorinated cyclic carbonate compounds, changing the chemical composition parameters while maintaining or improving performance. The fluorinated structure provides both environmental compliance and the necessary electrochemical stability for high-temperature operation above 4.5 V
Solution Approach 2:
The patent creates a composite electrolyte system combining fluorinated cyclic carbonate (as film-forming additive) with conventional carbonate solvents and lithium salts. This composite approach achieves environmental compliance while the synergistic interaction between components maintains high-temperature performance and discharge characteristics above 4.5 V
3Use of energy by moving object
If high-voltage lithium cobalt oxide and silicon carbon anodes are used to maximize energy density, then the energy density is improved, but surface side reactions increase causing capacity loss and safety issues
Solution Approach 1:
The fluorinated cyclic carbonate acts as an intermediary that preferentially reacts with the high-surface-area silicon carbon anode and high-voltage cathode to form a stable protective interface. This intermediary layer prevents direct harmful interactions between the electrode surfaces and the bulk electrolyte, reducing side reactions while enabling the use of high-energy-density materials
Solution Approach 2:
The patent employs preliminary action by having the fluorinated additive react first during initial charging cycles to form a stable protective film on the electrode surfaces. This pre-formed protective layer prevents subsequent harmful side reactions during normal operation, enabling safe use of high-voltage and high-surface-area materials
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 proposed electrolyte solution maintains excellent high-temperature storage and cycling performance while improving safety and electrochemical performance at high voltages, reducing battery bulging and internal resistance, even at 4.5 V or higher.
Implementation Method 1
the electrolytes will undergo oxidative decomposition on the surface of the battery
Implementation Method 2
A non-aqueous electrolyte comprising a lithium salt, an organic solvent and additives
Data Source
AI summary
A non-aqueous electrolyte and a high-voltage lithium battery comprising the same. In order to solve the problem that the high-temperature performance and discharge performance of the existing lithium batteries including non-aqueous electrolyte decreases with the increase of voltage, and the safety is not good, a non-aqueous electrolyte including a lithium salt, an organic solvent, and additives, the additives include a substance represented by the structural general formulawherein, R1 and R2 are the same, and R1 and R2 are alkylene, fluoroalkylene, alkyleneoxy, or fluoroalkyleneoxy; R3 and R4 are the same, and R3 and R4 are hydrogen, alkyl, alkyloxy, fluoroalkyl or fluoroalkyloxy, is provided. It ensures the high-temperature performance and cycling performance of lithium battery under conventional voltage, and meanwhile, when the voltage is increased to 4.5 V or even higher, the lithium battery still have excellent high-temperature performance and discharge performance, which ensures the safety and electrochemical performance.