Polyoligomeric Silsesquioxane Electrolyte for Dendrite Prevention

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Solution Overview

Problem

Current lithium-ion and lithium metal batteries face challenges in optimizing ionic conductivity and lithium ion transference number, leading to dendrite growth, which affects energy density and safety due to concentration polarization and anion depletion.

Innovation Solution

A composition comprising a polyether solvent and a polyoligomeric silsesquioxane with lithium salts, such as lithium bis(trifluoromethanesulfonyl)imide, which forms a liquid electrolyte with high ionic conductivity and lithium ion transference number, preventing dendrite formation by repelling anions and maintaining a stable interface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional electrolytes are used, then ionic conductivity can be achieved, but concentration polarization develops due to anion movement, leading to dendrite growth

Engineering Contradiction:

Improvedendrite preventionVSAvoidconcentration polarization

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The electrolyte is segmented into mobile lithium ions and immobile anions (through covalent attachment to polymer backbone or use of large polyoligomeric silsesquioxane anions), causing the anion to act as a stationary charge carrier that does not migrate to the electrode, thereby eliminating concentration polarization at the electrode interface

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The polymer matrix or polyoligomeric silsesquioxane structure serves as an intermediary that binds the anion, preventing its direct migration to the electrode while still allowing it to contribute to ionic conductivity through the bulk electrolyte

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If polymer single ion conductors are used to prevent concentration gradients, then lithium ion transference number increases, but ionic conductivity remains low

Engineering Contradiction:

Improvelithium ion transference numberVSAvoidionic conductivity

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The invention uses composite structures combining polyether solvents with polyoligomeric silsesquoxane frameworks, creating a material that exhibits both the high lithium ion transference number of single ion conductors and enhanced ionic conductivity through the unique properties of the silsesquioxane cage structure and its interaction with lithium ions

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The invention changes the physical and chemical parameters of the electrolyte by using polyoligomeric silsesquoxanes with specific cage structures, molecular weights, and functional groups, which alter the viscosity, segmental dynamics, and ion solvation properties to achieve higher conductivity while maintaining single ion conductor characteristics

Inventive Principle:

Principle #35Parameter changes

3Quantity of substance

If metallic lithium anodes are used to enhance energy density, then battery capacity increases, but dendrite growth and safety issues worsen

Engineering Contradiction:

Improveenergy densityVSAvoiddendrite growth

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The electrolyte composition is designed to preliminarily prevent dendrite formation by creating a stable solid electrolyte interface (SEI) and maintaining uniform lithium ion flux through the use of immobile anions, which eliminates concentration gradients that drive dendritic growth before it can occur during battery operation

Inventive Principle:

Principle #9Preliminary anti-action

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 achieves high ionic conductivity and lithium ion transference number, reducing dendrite growth and enhancing battery safety and energy density by maintaining a stable electrolyte interface and preventing anion aggregation.

Implementation Method 1

a polyoligomeric silsesquoxane of Formula (I) in a polyether solvent... liquid electrolyte with high ionic conductivity

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Implementation Method 2

preventing dendrite formation by repelling anions and maintaining a stable interface... high lithium ion transference number

Methodology Applied

Scientific EffectIon repulsion: Ion Repulsion/Attraction

Data Source

PatentUS10731010B2Multi-ionic salts and uses thereof

Publication Date: 2020.08.04 TEMPLE UNIV

AI summary

The invention provides a novel composition comprising a multi-ionic polyoligomeric silsesquioxane and a polyether solvent, optionally with an additional lithium salt. The composition of the invention allows for improved lithium ion transference over lithium salts alone by avoiding the problem of ion aggregation that reduces conductivity in single ion conductors. Also provided is a method for forming such a composition and a liquid electrolyte comprising a multi-ionic polyoligomeric silsesquioxane and a polyether solvent, optionally with an additional lithium salt.