Lithium Battery Electrolyte Additives for Stable Cathode Interface Films

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Solution Overview

Problem

Lithium secondary batteries face rapid deterioration and reduced performance due to interfacial reactivity between high-capacity positive electrodes and electrolytes, leading to decreased energy density and lifespan, particularly when lithium components on the electrode surface promote electrolyte decomposition.

Innovation Solution

An electrolyte solution comprising a lithium salt, solvent, and functional additives such as 2-(2′((tert-butoxycarbonyl)amino)ethoxy)-ethyl p-methylbenzenesulfonate, vinylene carbonate, fluoroethylene carbonate, and LiPO2F2, which form stable films on electrodes to enhance lithium ion conductivity and suppress oxidative decomposition, thereby improving the battery's lifespan and output.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If high-capacity positive electrode materials (Ni-rich NCM) are used to increase energy density, then the battery capacity increases, but the interfacial reactivity with electrolyte increases causing rapid deterioration

Engineering Contradiction:

Improvebattery capacityVSAvoidbattery lifespan

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent introduces a film-forming additive that acts as an intermediary substance between the high-capacity positive electrode and the electrolyte. This additive forms a stable interface film that mediates the interaction, preventing direct harmful reactions while allowing lithium ion transport, thus resolving the contradiction between high capacity and long lifespan

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the harmful interfacial reactivity into a beneficial effect by using the reactive lithium components on the electrode surface to form a stable protective film through controlled reaction with the film-forming additive. This film then prevents further harmful decomposition, transforming the initial harmful reactivity into a protective mechanism

Inventive Principle:

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

2Quantity of substance

If lithium components (Li2CO3 and LiOH) remain on the positive electrode surface to maintain high capacity, then the battery energy density increases, but electrolyte decomposition is promoted due to increased interfacial reactivity

Engineering Contradiction:

Improveenergy densityVSAvoidelectrolyte decomposition

Core Design Contradiction:

Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

The film-forming additive serves as an intermediary that intervenes between the lithium components on the electrode surface and the electrolyte. It forms a stable interface film that allows the lithium components to remain for high energy density while preventing them from causing electrolyte decomposition

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies preliminary anti-action by having the film-forming additive react first with the lithium components on the electrode surface to form a stable protective film before the harmful decomposition reactions can occur. This preliminary protective action prevents the subsequent harmful electrolyte decomposition

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 proposed electrolyte solution effectively prolongs the lifespan and output of lithium secondary batteries by forming protective films on electrodes, reducing cell resistance and maintaining performance at high temperatures, thus enhancing the battery's energy density and marketability.

Implementation Method 1

introducing an additive capable of forming an electrochemically and chemically stable film

Methodology Applied

Scientific EffectElectrochemical reaction:

Implementation Method 2

an electrolyte serving as a medium for transferring a lithium ion

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Implementation Method 3

The lithium secondary battery generates electrical energy and stores the same through a change in chemical potential when the lithium ion is intercalated or de-intercalated

Methodology Applied

Scientific EffectElectrochemical potential change:

Data Source

PatentUS11749838B2Electrolyte solution for lithium secondary batteries and lithium secondary battery including the same

Publication Date: 2023.09.05 HYUNDAI MOTOR CO LTD

AI summary

Disclosed are an electrolyte solution for lithium secondary batteries and a lithium secondary battery including the same.The electrolyte solution for lithium secondary batteries includes: a lithium salt; a solvent; and a functional additive, wherein the functional additive includes a first positive-electrode film additive, which is 2-(2′((tert-butoxycarbonyl)amino)ethoxy)-ethyl p-methylbenzenesulfonate, represented by the following Formula 1: