Propylene Carbonate Electrode Coating for Stable Solid-State Cycling

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Solution Overview

Problem

Existing electrode coatings in alkali-ion batteries lack sufficient cycle stability and performance during charging and discharging processes, particularly in solid-state batteries where thermal runaway and explosion risks are reduced but stability and safety remain concerns.

Innovation Solution

A process involving the coating of electrode surfaces with a cationic polymer dissolved in a solvent comprising at least 30 wt.-% propylene carbonate, allowing for even distribution and penetration into porous surfaces, combined with the integration of conductive salts and ionic liquids to enhance mechanical and chemical stability and diffusion of charged species.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional solvents like NMP or DMSO are used for coating electrodes, then the polymer coating can be applied, but hazardous substances are introduced and safety is compromised

Engineering Contradiction:

ImprovesafetyVSAvoidhazardous solvents

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces hazardous solvents (NMP, DMSO) with propylene carbonate, which is inherently safer and serves dual purposes as both solvent and solid electrolyte component. This converts the harmful aspect of solvent selection into a beneficial safety feature while maintaining coating functionality.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

Propylene carbonate acts as an intermediary substance that bridges the polymer coating and the solid electrolyte functions. It serves as the dissolution medium for applying the coating and simultaneously becomes part of the functional electrolyte system, eliminating the need for separate hazardous solvents.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If electrode surfaces are coated with polymer to improve stability, then cycle stability improves, but the coating process complexity increases

Engineering Contradiction:

Improvecycle stabilityVSAvoidcoating process

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the coating application process with the electrolyte formation process. The same propylene carbonate solution that provides the polymer coating also serves as the solid electrolyte precursor, combining two separate steps into one integrated process.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

Propylene carbonate performs multiple functions simultaneously: it acts as the coating solvent, the solid electrolyte medium, and the diffusion pathway for ions. This multi-functionality reduces the number of separate components and processes needed.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If porous electrode surfaces are coated to enhance performance, then cycle stability improves, but penetration of coating material becomes difficult

Engineering Contradiction:

Improvecycle stabilityVSAvoidcoating penetration

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent adjusts the physical parameters of the coating solution by using propylene carbonate, which provides appropriate viscosity and wetting properties to enable deep penetration into porous electrode structures while maintaining coating integrity.

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 coated electrodes exhibit improved cycling behavior, increased electric performance, and enhanced safety, enabling the use of electrodes with higher industrial capacities and improved mechanical flexibility, while avoiding the use of hazardous solvents like NMP and DMSO.

Implementation Method 1

Dissolution of a cationic polymer according to the following formula I wherein X - in a solvent comprising at least 30 wt.-% propylene carbonate

Methodology Applied

Scientific EffectDissolution: Solvation

Implementation Method 2

allowing for even distribution and penetration into porous surfaces

Methodology Applied

Scientific EffectCapillary action: Capillary Action

Data Source

PatentEP4451356A1Propylene carbonate solvent-based electrode coating processes and cationic polymer coated electrodes

Publication Date: 2024.10.23 EIDGENISSISCHE MATERIALPRUFUNGS- UND FORSCHUNGSANSTALT EMPA

Figure 1~2

AI summary

The invention relates to a process for coating electrode surfaces with a cationic polymer, wherein the process comprises at least the steps of: a) Provision of an electrode; b) Dissolution of a cationic polymer according to the following formula I wherein X- is selected from the group consisting of Cl-, FSI-, TFSI-, TFA-, BETI-, BF4-, DFOB-, BOB-, NO3-, PO2F2-; R1, R2 are independently selected from the group consisting of H, C1-C5 linear or branched alkyl or fluorinated derivatives thereof, and n = 10 - 10.000; in a solvent, wherein the solvent comprises equal to or greater than 30 wt.-% propylene carbonate; c) Coating of at least one electrode surface of the electrode provided in process step a) by deposition of the polymer solution obtained in process step b) to at least a part of the electrode surface; and d) Drying of the coated electrode obtained in process step c). In addition, the invention relates to a coated electrode and a solid electrolyte cell comprising a coated electrode.