Electrolyte Additives for Battery Low-Temperature Conductivity
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Solution Overview
Problem
Non-aqueous electrolyte batteries face challenges in maintaining performance at high and low temperatures, with existing solutions failing to provide sufficient durability and cycle characteristics, especially at temperatures below 0°C.
Innovation Solution
Incorporating difluorobis(oxalato)phosphate and tetrafluoro(oxalato)phosphate as additives in the electrolyte to form highly lithium-ion conductive coating films on electrodes, preventing decomposition and enhancing battery durability and low-temperature performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vinylene carbonate is added to the electrolyte to form a polymer coating film on the electrode, then decomposition of the electrolyte at the electrode surface is prevented, but internal resistance increases and battery capacity is insufficient at low temperatures of 0°C or lower
Solution Approach 1:
The patent combines vinylene carbonate (0.01-5 mass%) with fluorinated cyclic carbonate (0.01-5 mass%) to create a composite coating film on the electrode. This composite structure integrates the protective properties of vinylene carbonate with the low-temperature ionic conductivity of fluorinated cyclic carbonate, achieving both electrolyte stability and acceptable low-temperature performance
Solution Approach 2:
The patent modifies the chemical composition parameters of the coating film by introducing fluorinated cyclic carbonate with specific fluorine-containing groups. This changes the film's properties to reduce lithium ion transport resistance while maintaining protective functions, enabling operation at 0°C or lower
2Reliability
If difluorobis(oxalato)phosphate and monofluorophosphate or difluorophosphate are added to improve high-temperature cycle characteristics, then coating film formation on electrode interface is enhanced, but low-temperature performance remains insufficient
Solution Approach 1:
The patent creates a composite coating film by combining difluorobis(oxalato)phosphate (0.01-5 mass%) with fluorinated cyclic carbonate (0.01-5 mass%). This composite approach leverages the high-temperature stability from difluorobis(oxalato)phosphate while the fluorinated cyclic carbonate component ensures low-temperature ionic conductivity
Solution Approach 2:
Fluorinated cyclic carbonate acts as an intermediary substance that mediates between the electrode and the main electrolyte. It forms a protective interface layer that prevents direct contact between electrolyte and electrode, reducing decomposition at high temperatures while maintaining ion transport at low temperatures
3Quantity of substance
If the electrolyte uses aprotic solvents and lithium salts to achieve high energy density, then power storage capacity is improved, but performance deteriorates at high temperatures of 45°C or higher
Solution Approach 1:
Fluorinated cyclic carbonate and difluorobis(oxalato)phosphate serve as intermediary protective layers between the high-energy-density electrolyte components (aprotic solvents and lithium salts) and the electrode. This intermediary layer prevents direct decomposition reactions at high temperatures while allowing ion transport, thus maintaining both energy density and high-temperature stability
Solution Approach 2:
The patent converts the potential harm of electrolyte decomposition at high temperatures into a beneficial protective coating formation. The fluorinated cyclic carbonate and difluorobis(oxalato)phosphate intentionally decompose to form stable protective films on the electrode, preventing further harmful decomposition of the main electrolyte
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 combined use of these additives improves cycle characteristics, high-temperature storage stability, and low-temperature performance, ensuring battery functionality even at 0°C or lower, with improved discharge capacity retention and conductivity.
Implementation Method 1
highly lithium-ion conductive coating films can be formed by decomposition of difluorobis(oxalato)phosphate on positive and negative electrodes
Implementation Method 2
The non-aqueous electrolyte contains a single kind of aprotic solvent, or a mixed solvent of two or more kinds of aprotic solvents... and a lithium salt such as LiPF6, LiBF4, (CF3SO2)2NLi or (C2F5SO2)2NLi as a solute
Data Source
AI summary
An electrolyte for a non-aqueous electrolyte battery according to the present invention contains a non-aqueous organic solvent; a solute; and both of difluorobis(oxalato)phosphate and tetrafluoro(oxalate)phosphate as additives. A non-aqueous electrolyte battery according to the present invention uses the above electrolyte. By the composite effect of the difluorobis(oxalato)phosphate and tetrafluoro(oxalate)phosphate in the non-aqueous electrolyte and the non-aqueous electrolyte battery, it is possible to improve not only the cycle characteristics and high-temperature storage stability of the battery but also the low-temperature characteristics of the battery at temperatures of 0°C or lower.