Fluorinated Battery Electrolyte for Stable Anode Interface Films
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Solution Overview
Problem
Commercial lithium-ion batteries with graphite as the negative electrode material face limitations in energy density, leading to poor coulombic efficiency and cycling performance due to large volume expansion of alternative materials like silicon and tin, which consume excessive electrolyte and result in low cycling stability.
Innovation Solution
A battery electrolytic solution with a high content of organic solvents having a special structure, such as substituted sulfinamide or sulfonamide compounds, that form a stable interface film on the negative electrode, reducing side reactions and improving coulombic efficiency and cycling performance by isolating other solvents and complexing with metal ions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-capacity negative electrode materials (silicon, tin, or metal) are used to replace graphite, then theoretical capacity and energy density are improved, but volume expansion during charging and discharging causes excessive electrolyte consumption and poor cycling performance
Solution Approach 1:
The patent introduces a fluorinated cyclic carbonate additive as an intermediary substance that mediates between the high-capacity negative electrode material and the electrolyte. This additive preferentially reacts with the electrode material to form a stable protective film, preventing direct contact between the electrolyte and electrode, thereby reducing electrolyte consumption and improving cycling stability while maintaining high capacity
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte by incorporating fluorinated cyclic carbonate compounds with specific molecular structures. This parameter change alters the electrochemical behavior at the electrode interface, enabling the formation of a more stable solid electrolyte interface (SEI) layer that accommodates volume expansion and reduces side reactions
2Reliability
If functional additives are added to improve battery performance, then coulombic efficiency may be improved, but the additives are exhausted through battery formation and capacity grading, resulting in poor cycling performance
Solution Approach 1:
The fluorinated cyclic carbonate additive enables the battery system to be self-service by allowing the electrode to self-form a stable protective film during initial cycles. This self-formed film continuously protects the electrode throughout cycling, eliminating the need for ongoing additive consumption and maintaining performance stability over extended cycling
Solution Approach 2:
The patent utilizes the formation of a thin, flexible protective film on the negative electrode surface. This film acts as a dynamic barrier that can accommodate electrode volume changes while maintaining its integrity, providing long-term protection against electrolyte decomposition and electrode material degradation throughout the battery's cycling life
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 solution significantly enhances coulombic efficiency, cycling stability, and high-temperature preservation of lithium-ion batteries by forming a stable interface film that reduces dendrite formation and side reactions, thereby improving overall battery performance.
Implementation Method 1
The first organic solvent and the second organic solvent are a substituted sulfinamide or substituted sulfonamide compound. The substituted sulfinamide or substituted sulfonamide compound can be preferentially reduced on the surface of the negative electrode than other components in the electrolytic solution, so that a stable interface film containing a metal fluoride, a metal nitride, a sulfide, and other compounds is formed on the surface of the negative electrode
Implementation Method 2
Sulfinamide and/or sulfonamide on the polar end can be complexed with metal ions (for example, lithium ions) and more easily close to the electrode side, so that the metal ions (for example, lithium ions) easily reach a surface of the electrode
Data Source
AI summary
This application provides a battery electrolytic solution, including an electrolyte salt and a non-aqueous organic solvent. The non-aqueous organic solvent includes a first organic solvent shown in a formula (I) and/or a second organic solvent shown in a formula (II): R1—S(═O)x—N(—R3)—R2 formula (I); and R1—S(═O)x—N(—R3)—S(═O)y—R4 formula (II). R1 and R4 are separately selected from fluoroalkyl, fluoroalkoxy, fluoroalkenyl, fluoroalkenyloxy, fluoroaryl, or fluoroaryloxy. R2 and R3 are separately selected from alkyl, alkoxy, alkenyl, alkenyloxy, aryl, or aryloxy. x is 1 or 2, and y is 1 or 2. A total content in mass of the first organic solvent and/or the second organic solvent in the electrolytic solution ranges from 10% to 90%. The electrolytic solution includes the first organic solvent and/or the second organic solvent of a high content in mass.