High-Voltage Battery Electrolyte Composition for Longer Cycle Life
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Solution Overview
Problem
Existing electrolytes in high energy density lithium-ion batteries suffer from side reactions with positive electrode active materials at high working voltages, leading to cycle lifespan degradation and increased cycle gas generation, with a lack of systematic understanding and scarce solutions.
Innovation Solution
An electrolyte composition comprising specific ratios of ethylene carbonate, propylene carbonate, fluorinated ethylene carbonate, and additives like 1,3-propane sultone and ethylene sulfate, optimized to enhance oxidation resistance and electrochemical stability, reducing side reactions while maintaining lithium ion transport and film-forming capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the positive electrode active material activity is increased to achieve higher energy density, then the battery energy density is improved, but the oxidation stability of the positive electrode active material deteriorates, leading to side reactions with the electrolyte
Solution Approach 1:
The patent introduces a mediator substance (specific electrolyte additive) that acts as an intermediary between the high-energy-density positive electrode active material and the electrolyte. This mediator forms a protective interface layer that prevents direct contact and harmful oxidation reactions, allowing the high-energy material to function without degradation. The additive serves as a buffer that enables the use of higher-energy materials while maintaining system stability.
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte by introducing specific additives at controlled concentrations. This parameter change alters the electrochemical window and interfacial properties of the electrolyte, making it compatible with high-voltage, high-energy-density positive electrode materials. The parameter adjustment enables the system to operate at higher energies without sacrificing stability.
2Use of energy by moving object
If the electrolyte is used at high working voltage to support high energy density batteries, then the battery energy density is improved, but the electrolyte undergoes side reactions with the positive electrode active material, causing cycle lifespan degradation
Solution Approach 1:
The patent applies preliminary action by having the electrolyte additive react first with the positive electrode active material surface during initial cycles to form a stable protective layer. This preliminary reaction prevents subsequent harmful side reactions during normal battery operation. The protective layer is formed in advance, before the actual high-voltage operation begins, thereby preserving the battery's cycle lifespan while enabling high energy density operation.
Solution Approach 2:
The electrolyte additive serves as a mediator that forms an intermediate protective layer between the electrolyte and the positive electrode active material. This intermediate layer acts as a barrier that prevents direct harmful interactions while allowing ionic transport, thereby extending the battery's cycle lifespan under high-voltage conditions.
3Reliability
If the electrolyte composition is modified to reduce side reactions at high voltage, then the cycle lifespan is improved, but the conductivity performance of the electrolyte may deteriorate
Solution Approach 1:
The patent carefully adjusts the concentration parameters of the electrolyte additive to achieve optimal performance. By controlling the additive content within a specific range, the patent ensures that the protective function is sufficient to improve cycle lifespan while the electrolyte's conductivity is maintained at acceptable levels. This parameter optimization resolves the trade-off between stability and power performance.
Solution Approach 2:
The patent applies local quality by concentrating the protective function at the electrode-electrolyte interface where it is most needed, rather than uniformly modifying the bulk electrolyte properties. The additive forms a localized protective layer at the interface, allowing the bulk electrolyte to maintain its high conductivity. This spatial differentiation enables simultaneous improvement of cycle lifespan and preservation of power performance.
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 optimized electrolyte effectively suppresses cycle gas generation and improves cycle lifespan by reducing side reactions at high voltages, ensuring conductivity and initial impedance are maintained, thus enhancing battery performance.
Implementation Method 1
The solvent includes ethylene carbonate, propylene carbonate, fluorinated ethylene carbonate, and linear carbonate... ensuring the conductivity performance of the electrolyte
Implementation Method 2
the additive includes 1,3-propane sultone and ethylene sulfate... effectively suppresses cycle gas generation and improves cycle lifespan by reducing side reactions at high voltages
Data Source
AI summary
Provided are an electrolyte and a secondary battery. The electrolyte includes a lithium salt and a solvent. The solvent includes ethylene carbonate, propylene carbonate, fluorinated ethylene carbonate, and linear carbonate. A mass percentage of the ethylene carbonate relative to the solvent is 2% to 10%. A sum of a mass of the propylene carbonate and the fluorinated ethylene carbonate relative to the mass percentage of the solvent is 10% to 30%. The electrolyte may well match batteries with high working voltage, while ensuring that the initial impedance of the battery does not deteriorate, effectively improving the issues of poor cycle performance and large cycle gas generation of the battery.