Ionic Liquid Polymer Electrolyte for Lithium Metal Batteries

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Solution Overview

Problem

Lithium secondary batteries with lithium metal or lithium metal alloys face chemical instability, leading to decreased capacity and lifespan due to reactivity with moisture and oxygen, and the formation of dendrites, which hinders ion conductivity and electrochemical stability.

Innovation Solution

An electrolyte comprising an ionic liquid polymer with a specific repeating unit, which includes a pyrrolidinium cation and a wide potential window, is used to enhance mechanical properties and ion conductivity, suppressing dendrite growth and improving electrochemical stability, even at high voltages.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If lithium metal or lithium metal alloy is used as negative electrode, then high energy density is achieved, but chemical stability deteriorates due to reactivity with moisture and oxygen

Engineering Contradiction:

Improveenergy densityVSAvoidchemical stability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

An ionic liquid polymer electrolyte is introduced as an intermediary layer between the lithium metal negative electrode and the external environment. This electrolyte forms a protective interface that prevents direct contact between lithium metal and moisture/oxygen, thereby maintaining chemical stability while preserving the high energy density benefits of lithium metal electrodes

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The ionic liquid polymer electrolyte creates an inert chemical environment around the lithium metal electrode. The polymer matrix and ionic liquid components provide chemical inertness that protects the reactive lithium metal from degradation by atmospheric moisture and oxygen, enabling stable operation without requiring external protective atmospheres

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

2Quantity of substance

If lithium metal or lithium metal alloy is used as negative electrode, then high capacity is achieved, but dendrite formation occurs leading to decreased lifespan

Engineering Contradiction:

ImprovecapacityVSAvoidlifespan

Core Design Contradiction:

Quantity of substanceVSDuration of action of stationary object

Solution Approach 1:

The ionic liquid polymer electrolyte creates a localized protective environment at the electrode-electrolyte interface. By modifying the local chemical and physical properties at this critical interface, the electrolyte promotes uniform lithium ion deposition and prevents dendrite formation, thereby extending battery lifespan while maintaining high capacity

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The electrolyte provides preemptive protection against dendrite formation by establishing a stable solid electrolyte interface (SEI) layer before dendrites can grow. This protective interface acts as a cushion that prevents the harmful effects of dendrite formation, allowing the battery to achieve its full capacity potential over an extended lifespan

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Ease of manufacture

If conventional electrolyte is used, then ease of manufacture is maintained, but ion conductivity and mechanical properties are insufficient at room temperature

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidion conductivity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The electrolyte combines ionic liquid components with a polymer matrix to create a composite material that exhibits both high ion conductivity and adequate mechanical properties at room temperature. This composite structure leverages the advantages of both materials while maintaining ease of manufacture through established polymer electrolyte fabrication techniques

Inventive Principle:

Principle #40Composite materials

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 electrolyte provides improved mechanical properties, ion conductivity, and electrochemical stability, leading to enhanced charging and discharging characteristics and extended lifespan of lithium secondary batteries.

Implementation Method 1

an electrolyte for a secondary battery, a method of preparing the electrolyte, and a secondary battery including the electrolyte

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Implementation Method 2

thereby having excellent electrochemical stability and charging and discharging characteristics

Methodology Applied

Scientific EffectElectrochemical stabilization:

Data Source

PatentUS11424481B2Electrolyte for secondary battery, method of preparing electrolyte, and secondary battery including electrolyte

Publication Date: 2022.08.23 SAMSUNG ELECTRONICS CO LTD

AI summary

An electrolyte for a secondary battery, the electrolyte including an ionic liquid polymer including a repeating unit represented by Formula 1:wherein, in Formula 1, CY, R1, R2, R3, X1−, n, and m are the same as described in the specification.