Dry Electrode PTFE Composite Binder for Low-Voltage Stability

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Solution Overview

Problem

Conventional dry energy storage device electrodes using polytetrafluoroethylene (PTFE) binders suffer from irreversible capacity loss and electrochemical instability, leading to reduced energy density and durability, especially at lower operating voltages, due to low ionic conductivity and porosity issues.

Innovation Solution

The use of a PTFE composite binder material incorporating polyvinylidene fluoride (PVDF), PVDF co-polymer, or poly(ethylene oxide) (PEO) with PTFE, which is fibrillized through high shear processes like jet-milling, to form electrodes with improved mechanical integrity and ionic conductivity, reducing irreversible capacity loss and enhancing electrochemical performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If PTFE binder is used in dry electrode process, then manufacturing complexity is reduced and drying costs are avoided, but irreversible capacity loss increases and electrochemical stability deteriorates

Engineering Contradiction:

Improvemanufacturing process complexityVSAvoidelectrochemical stability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent uses composite binder materials combining PTFE with other polymers (such as polyacrylonitrile, carboxymethyl cellulose, or styrene-butadiene rubber) to create a binder system that maintains the dry process advantages while improving electrochemical stability and reducing capacity loss through synergistic effects of the composite components

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent modifies the chemical composition and physical properties of the binder material by selecting specific polymer types and ratios, changing parameters such as ionic conductivity, mechanical adhesion, and electrochemical compatibility to resolve the contradiction between simple dry processing and electrochemical performance

Inventive Principle:

Principle #35Parameter changes

2Loss of time

If PTFE binder is used in dry electrode process, then drying time and cost are reduced, but ionic conductivity decreases and porosity issues arise

Engineering Contradiction:

Improvedrying timeVSAvoidionic conductivity

Core Design Contradiction:

Loss of timeVSReliability

Solution Approach 1:

The composite binder system combines PTFE's processing advantages with complementary polymers that provide enhanced ionic conductivity pathways, creating a multi-phase structure where different materials perform different functions to simultaneously achieve fast processing and good ionic transport

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent optimizes the porosity of the electrode structure by controlling binder composition and processing parameters, creating a controlled porous network that facilitates ion transport while maintaining the benefits of dry processing and avoiding excessive drying requirements

Inventive Principle:

Principle #31Porous materials

3Quantity of substance

If PTFE binder is used at lower operating voltages, then energy storage capacity increases, but irreversible capacity loss increases and durability decreases

Engineering Contradiction:

Improveenergy storage capacityVSAvoiddurability

Core Design Contradiction:

Quantity of substanceVSDuration of action of stationary object

Solution Approach 1:

The composite binder system is specifically designed to be electrochemically stable at lower operating voltages, using polymer combinations that resist degradation and maintain binding effectiveness throughout extended cycling, thereby enabling high capacity operation without sacrificing durability

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent employs binder materials with pre-established chemical stability and resistance to electrochemical degradation at low voltages, providing protective effects against capacity loss mechanisms before they can occur during device operation and cycling

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 PTFE composite binder material significantly reduces irreversible capacity loss and maintains energy density, achieving electrochemical stability at low voltages, comparable to wet slurry coating methods while avoiding the drying costs associated with traditional wet processes.

Implementation Method 1

The PTFE composite binder material, which can include PTFE and at least one of polyvinylidene fluoride (PVDF), a PVDF co-polymer, and poly(ethylene oxide) (PEO), and is fibrillized through high shear processes like jet-milling

Methodology Applied

Scientific EffectJet-milling: Jet Erosion

Data Source

PatentUS11876230B2Dry energy storage device electrode and methods of making the same

Publication Date: 2024.01.16 TESLA INC

AI summary

An energy storage device can include a cathode and an anode, where at least one of the cathode and the anode are made of a polytetrafluoroethylene (PTFE) composite binder material including PTFE and at least one of polyvinylidene fluoride (PVDF), a PVDF co-polymer, and poly(ethylene oxide) (PEO). The energy storage device can be a lithium ion battery, a lithium ion capacitor, and/or any other lithium based energy storage device. The PTFE composite binder material can have a ratio of about 1:1 of PTFE to a non-PTFE component, such a PVDF, PVDF co-polymer and/or PEO. Methods of fabricating the anode and/or the cathode of the energy storage device are also disclosed.