Sodium Battery Paste Viscosity Stabilization

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Solution Overview

Problem

Conventional electrode mixture pastes for sodium secondary batteries tend to gelate prematurely, making it difficult to apply them onto current collectors due to increased viscosity, which requires expensive moisture-controlled facilities and high energy maintenance.

Innovation Solution

An electrode mixture paste for sodium secondary batteries is developed, containing a positive electrode active material, electroconductive material, binder, organic solvent, and an acid with a valence number of 2 or more, which maintains stable viscosity and fluidity, allowing for easier application without specialized facilities, and includes a specific composition and reaction mechanism to prevent gelation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional electrode mixture paste is used, then the paste can be produced with standard materials, but the paste gels prematurely causing increased viscosity and difficult application

Engineering Contradiction:
Improveease of applicationVSAvoidviscosity stability
Core Design Contradiction:
Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The patent introduces a specific binder (polyvinylidene fluoride or polytetrafluoroethylene) as an intermediary substance that mediates between the electrode active material and organic solvent, preventing premature gelation while maintaining stable viscosity during storage and application processes

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the chemical composition parameters of the electrode mixture paste by specifying exact binder types (polyvinylidene fluoride or polytetrafluoroethylene) and their proportions, which changes the paste's rheological properties to prevent gelation and maintain stable viscosity

Inventive Principle:
Principle #35Parameter changes

2Stability of the object's composition

If moisture-controlled facilities are used to prevent gelation, then the paste stability is improved, but the facility cost and energy consumption increase

Engineering Contradiction:
Improvepaste stabilityVSAvoidenergy consumption
Core Design Contradiction:
Stability of the object's compositionVSUse of energy by stationary object

Solution Approach 1:

The electrode mixture paste formulation is designed to be self-stabilizing through the selection of specific fluorinated binders that inherently prevent gelation without requiring external moisture control facilities, making the system self-sufficient and eliminating the need for expensive controlled environment equipment

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces expensive moisture-controlled facilities with a chemically stable paste formulation using inexpensive fluorinated binders, achieving the same stability goal through material selection rather than environmental control infrastructure

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

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 ensures stable application and adhesion of the electrode mixture to the current collector, preventing separation and maintaining high discharging capacity, thus enhancing the industrial usability and efficiency of sodium secondary batteries.

Implementation Method 1

The gelation means to generate a wet solid by chemical reaction of a substance or an impurity thereof in the electrode mixture paste. When gelation occurs, the fluidity of the electrode mixture paste becomes of a state in which the fluidity is considerably decreased because of changing the viscosity

Methodology Applied
Scientific EffectGelation prevention:

Implementation Method 2

an electrode mixture paste containing the electrode mixture and an organic solvent is applied onto the current collector and dried

Methodology Applied
Scientific EffectDissolution: Solvation

Implementation Method 3

the paste easily turns into gel prior to applying it onto a current collector after the electrode mixture paste is produced

Methodology Applied
Scientific EffectAdhesion: Adhesive

Data Source

PatentUS10658653B2Electrode mixture paste for sodium secondary cell, positive electrode for sodium secondary cell, and sodium secondary cell
Publication Date: 2020.05.19 TOYOTA JIDOSHA KK

AI summary

An electrode mixture paste for a sodium secondary battery contains a positive electrode active material capable of being doped and dedoped with a sodium ion, an electroconductive material, a binder, an organic solvent, and an acid having a valence number of 2 or more. The electrode mixture paste for a sodium secondary battery gives little change in viscosity with lapse of time even when there are no special facilities.