Battery Electrolyte Composition for PF5 and HF Suppression
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Solution Overview
Problem
Lithium-ion batteries face issues with thermal instability due to the formation of phosphorus pentafluoride (PF5) and hydrofluoric acid (HF), which degrade the positive electrode material and reduce battery capacity, and existing additives exacerbate gas generation and storage performance under high-temperature conditions.
Innovation Solution
An electrolyte composition including vinylene carbonate (VC) and a boron-containing compound, such as lithium tetrafluoroborate, is used to inhibit PF5 and HF formation, forming a stable solid electrolyte interface (SEI) film that enhances thermal stability and reduces gas generation, while the boron atom improves lithium-ion transport and impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium salts are used in the electrolyte, then the battery can operate, but thermal stability deteriorates due to decomposition forming PF5 and HF
Solution Approach 1:
The patent introduces a boron-containing compound as an intermediary substance that reacts with PF5 to form a complex, preventing PF5 from reacting with water to form HF. This mediator approach resolves the contradiction by maintaining battery operation while eliminating the thermal stability issue caused by HF formation
Solution Approach 2:
The patent converts the harmful PF5 decomposition product into a beneficial complex by having it react with the boron-containing compound. The PF5 that would otherwise cause harm is transformed into a stable complex that improves overall battery performance and thermal stability
2Reliability
If a sulfonyl/sulfonate compound including an imidazole group is used to reduce PF5 and HF content, then Lewis acidity of PF5 is reduced, but gas generation increases due to ring-opening decomposition of cyclic carbonate solvents
Solution Approach 1:
The patent extracts the problematic imidazole group from the sulfonyl/sulfonate compound structure and replaces it with a boron-containing compound. This extraction eliminates the harmful ring-opening decomposition effect while retaining the beneficial PF5 complexation capability
Solution Approach 2:
The patent changes the chemical structure parameter by replacing the imidazole group with a boron-containing compound, fundamentally altering the molecular properties to eliminate gas generation while maintaining PF5 scavenging functionality
3Reliability
If conventional additives are used to inhibit PF5 reaction, then HF formation is reduced, but storage performance deteriorates under high-temperature conditions
Solution Approach 1:
The patent creates a composite electrolyte system combining the boron-containing compound with existing electrolyte components. This composite approach achieves HF formation inhibition while maintaining excellent high-temperature storage performance through synergistic effects
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 composition significantly reduces PF5 and HF content, improving the electrochemical performance of lithium-ion batteries by enhancing high- and low-temperature cycle performance and reducing gas generation during charge-discharge processes.
Implementation Method 1
the nitrogen-including five-membered heterocycle in the compound exhibits Lewis basicity, enabling it to form a complex with PF5
Implementation Method 2
forming a stable solid electrolyte interface (SEI) film that enhances thermal stability
Implementation Method 3
the boron atom improves lithium-ion transport and impedance
Implementation Method 4
some lithium salts have poor thermal stability and are prone to decompose under high-temperature conditions to form phosphorus pentafluoride (PF5)
Data Source
AI summary
Provided in the present application are an electrolyte and the use thereof. The electrolyte comprises a first additive as shown in formula 1, vinylene carbonate and a boron-containing compound.