Paste Electrolyte Anionic Transport Control

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Solution Overview

Problem

Current rechargeable lithium batteries face issues with anionic diffusion dominating during fast charge and discharge, leading to electrolyte depletion, reduced conductivity, and potential electrolyte decomposition, while existing solutions fail to achieve optimal lithium ion conductivity without compromising anionic transport.

Innovation Solution

A paste electrolyte comprising an organic solvent with a low to medium dielectric constant and swollen hectorite, where the hectorite is exfoliated into sheets no larger than 2 micrometers, is used to limit anionic transport between the anode and cathode, maintaining high lithium ion conductivity and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If liquid electrolyte is used in rechargeable lithium batteries, then high ionic conductivity is achieved, but anionic diffusion dominates during fast charge and discharge causing electrolyte depletion and reduced performance

Engineering Contradiction:

Improveionic conductivityVSAvoidfast charge and discharge performance

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent uses a composite gel polymer electrolyte consisting of polymer matrix (such as polyethylene oxide) combined with inorganic fillers (such as alumina, silica, or titania particles). This composite structure provides high ionic conductivity while the inorganic fillers create tortuous paths that hinder anionic diffusion, thereby improving fast charge and discharge performance without sacrificing conductivity

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent incorporates porous inorganic fillers with controlled pore structures into the electrolyte. These porous materials provide channels preferential for lithium ion transport while their complex pore geometry creates diffusion barriers for anions, resolving the contradiction between maintaining high ionic conductivity and preventing anionic diffusion during fast charging

Inventive Principle:

Principle #31Porous materials

2Productivity

If Li transference number is increased to 1 using ideal Li-ion conductive membrane, then anionic diffusion is completely blocked, but charge transfer at solid electrolyte-liquid electrolyte interface becomes too slow

Engineering Contradiction:

Improveanionic diffusion blockingVSAvoidcharge transfer speed

Core Design Contradiction:

ProductivityVSSpeed

Solution Approach 1:

The patent modifies the interface properties between solid and liquid electrolytes by adjusting composition ratios, particle sizes, and surface treatments of inorganic fillers. These parameter changes optimize the charge transfer kinetics at the interface while maintaining the blocking function against anionic diffusion, achieving both high productivity and fast charge transfer speed

Inventive Principle:

Principle #35Parameter changes

3Reliability

If polymer composites with inorganic fillers are used to improve conductivity and Li-transference number, then transport properties are enhanced, but further significant improvements are limited due to structural changes saturation

Engineering Contradiction:

Improvetransport propertiesVSAvoidfurther improvement potential

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent introduces dynamic adjustable parameters such as variable particle size distributions, multiple filler combinations, and controllable polymer chain lengths. These dynamic elements allow continuous optimization of transport properties and Li-transference number, preventing saturation and enabling further significant improvements beyond current composite electrolyte performance

Inventive Principle:

Principle #15Dynamics

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

This approach enhances the electrochemical properties and cycling stability of lithium batteries by restricting anionic diffusion without impairing lithium transport, ensuring long-term chemical stability and maintaining energy density and cost-effectiveness.

Implementation Method 1

clays, with the clays being swollen by the solvent

Methodology Applied

Scientific EffectSwelling:

Implementation Method 2

allow fast diffusion of lithium ions

Methodology Applied

Scientific EffectDiffusion: Diffusion

Implementation Method 3

hinders a fast anionic diffusion

Methodology Applied

Scientific EffectDiffusion barrier: Diffusion Barrier

Data Source

PatentEP2038958B1Paste electrolyte and rechargeable lithium battery containing the same

Publication Date: 2017.09.06 LG CHEM LTD

Figure 1

AI summary

The present invention provides a paste electrolyte comprising an organic solvent of not high dielectric constant, soluble lithium salts, and clays, with the clays being swollen by the solvent, and rechargeable lithium batteries containing the paste electrolyte. The paste electrolyte according to the present invention can improve the electrochemical properties and cycling stability of rechargeable lithium batteries by limiting the anionic transport between anode and cathode without significantly decreasing the lithium transport rate, particularly during fast charge and discharge.