PTFE-Coated Carbon Anode for Aqueous Li-Ion Batteries

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Aqueous lithium ion secondary batteries face limitations in using carbon-based anode active materials due to restricted potential windows and low operating voltages, despite advancements in expanding the potential window of aqueous electrolyte solutions.

Innovation Solution

Incorporating a composite of carbon-based anode active materials with polytetrafluoroethylene (PTFE), where PTFE is arranged over the surface of the anode active material, forming a composite with specific FT-IR and Raman spectroscopy characteristics, to enhance lithium ion conductivity and suppress water molecule presence, thereby expanding the potential window and improving operating voltage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a conventional aqueous electrolyte solution is used, then the battery has a narrow potential window which restricts active materials selection, but using high concentration LiTFSI expands the potential window to 1.9-4.9V

Engineering Contradiction:

Improvepotential window rangeVSAvoidelectrolyte concentration

Core Design Contradiction:

Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The patent changes the concentration parameter of the electrolyte by using high concentration LiTFSI (21 mol/kg or higher) to expand the potential window from conventional narrow ranges to 1.9-4.9V, enabling broader active material selection

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite anode structure combining carbon-based active material with PTFE coating, where the PTFE layer (20-90 mass%) forms a protective interface that enables stable operation at lower potentials while maintaining the expanded potential window

Inventive Principle:

Principle #40Composite materials

2Power

If high concentration LiTFSI electrolyte is used to expand potential window, then the operating voltage increases, but carbon-based anode materials cannot be used due to reduction side limitation at 1.83V

Engineering Contradiction:

Improveoperating voltageVSAvoidanode active material selection

Core Design Contradiction:

PowerVSAdaptability or versatility

Solution Approach 1:

The PTFE layer acts as an intermediary between the carbon-based anode material and the high concentration LiTFSI electrolyte, providing a protective interface that prevents direct harmful interactions while allowing lithium ion transport, thus enabling carbon materials to operate at lower potentials

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The PTFE forms a thin film coating (20-90 mass%) over the carbon-based anode material surface, creating a flexible protective shell that enables stable charge-discharge at potentials below the conventional 1.83V reduction limit

Inventive Principle:

Principle #30Flexible shells and thin films

3Adaptability or versatility

If carbon-based anode material is used with high concentration electrolyte, then the potential window expands, but the battery operates at low voltage due to reduction side constraints

Engineering Contradiction:

Improvepotential windowVSAvoidoperating voltage

Core Design Contradiction:

Adaptability or versatilityVSPower

Solution Approach 1:

The patent optimizes the PTFE content parameter (20-90 mass%) and heating temperature parameter (glass transition to vaporization temperature range) to achieve the optimal balance between expanding potential window and maintaining high operating voltage through improved lithium ion conductivity

Inventive Principle:

Principle #35Parameter changes

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 composite anode active material with PTFE allows for stable charge-discharge of carbon-based materials at lower potentials, expanding the potential window and improving the operating voltage of aqueous lithium ion secondary batteries.

Implementation Method 1

PTFE has a characteristic of repelling electrons; when the PTFE surface is arranged over the anode active material, electron-giving and receiving between the anode active material and the aqueous electrolyte solution can be suppressed

Methodology Applied

Scientific EffectElectron repulsion: Ion Repulsion/Attraction

Implementation Method 2

PTFE has a characteristic of repelling electrons and also has hydrophobicity; when the PTFE surface is arranged over the anode active material, water molecules can be kept away

Methodology Applied

Scientific EffectHydrophobicity: Hydrophobe

Implementation Method 3

dissolving a high concentration of lithium bis(trifluoromethanesulfonyl)imide (hereinafter may be referred to as 'LiTFSI') in an aqueous electrolyte solution can expand the range of a potential window

Methodology Applied

Scientific EffectSolvation: Solvation

Data Source

PatentEP3457465B1Aqueous lithium ion secondary battery and method for producing aqueous lithium ion secondary battery

Publication Date: 2022.11.30 TOYOTA JIDOSHA KK

Figure 1
Figure 2
Figure 3

AI summary

Decomposition of an aqueous electrolyte solution when an aqueous lithium ion secondary battery is charged and discharged is suppressed, and the operating voltage of the battery is improved. The aqueous lithium ion secondary battery includes an anode, a cathode, and an aqueous electrolyte solution, the anode including a composite of an anode active material and polytetrafluoroethylene, wherein peaks of the polytetrafluoroethylene at around 1150 cm-1 and at around 1210 cm-1 are observed in FT-IR measurement of the composite, but a peak of the polytetrafluoroethylene at around 729 cm-1 is not observed in Raman spectroscopy measurement of the composite.