Electrolyte Additive for Lithium Battery Anode Protection

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Solution Overview

Problem

Existing lithium ion batteries face challenges with the use of propylene carbonate as an electrolyte solvent due to its intercalation into graphite anode materials, leading to structural destruction and limited low-temperature applications, along with concerns over flammability and cycling stability.

Innovation Solution

Incorporating methyl-2-methyl-1,3-dioxolane-2-carboxylate into the electrolyte composition, which includes aprotic organic solvents and conducting salts, to create a stable electrolyte that allows for the use of propylene carbonate at low temperatures and prevents anode deterioration, enhancing cycle life and rate capability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If propylene carbonate is used as electrolyte solvent to improve low-temperature performance, then low-temperature application capability is improved, but graphite anode structural destruction occurs due to intercalation

Engineering Contradiction:

Improvelow-temperature application capabilityVSAvoidgraphite anode structural stability

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

Methyl-2-methyl-1,3-dioxolane-2-carboxylate acts as an intermediary substance that mediates between propylene carbonate and graphite anode. It forms a protective film on the graphite surface that prevents propylene carbonate intercalation while allowing lithium ion transport, thus enabling low-temperature performance without graphite destruction

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the harmful intercalation effect of propylene carbonate into a beneficial protective mechanism. By controlling the electrolyte composition to include specific additives, the intercalation tendency is redirected to form a stable protective film rather than destroying the graphite structure, thus transforming the harmful effect into a protective benefit

Inventive Principle:

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

2Quantity of substance

If ethylene carbonate is used to improve solubility of conductive salts, then solubility is improved, but melting point increases limiting low-temperature use

Engineering Contradiction:

Improvesolubility of conductive saltsVSAvoidmelting point

Core Design Contradiction:

Quantity of substanceVSTemperature

Solution Approach 1:

The patent changes the chemical composition parameters of the electrolyte by introducing methyl-2-methyl-1,3-dioxolane-2-carboxylate and controlling the ratio of cyclic to acyclic carbonates. This composition modification maintains high salt solubility while lowering the overall melting point of the electrolyte system, enabling low-temperature operation

Inventive Principle:

Principle #35Parameter changes

3Speed

If acyclic carbonates are added to reduce viscosity, then viscosity is reduced, but flammability increases

Engineering Contradiction:

ImproveviscosityVSAvoidflammability

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The patent creates a composite electrolyte system combining cyclic carbonates (low flammability but high viscosity), acyclic carbonates (low viscosity but high flammability), and methyl-2-methyl-1,3-dioxolane-2-carboxylate (moderate properties). This composite formulation achieves optimal balance by combining the advantages of different components while mitigating their individual disadvantages, resulting in low viscosity with reduced flammability

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 composition with methyl-2-methyl-1,3-dioxolane-2-carboxylate enables the use of propylene carbonate in lithium batteries with graphite anodes, improving low-temperature performance, cycle life, and reducing flammability risks, while maintaining high discharge capacity and stability.

Implementation Method 1

This film is often called solid electrolyte interface (SEI). The SEI is permeable for lithium ions and protects the electrolyte composition from direct contact with the anode and vice versa. It is formed by reductive decomposition of components of the electrolyte composition like solvents, e.g. carbonates, esters, and ethers, and conductive salts on the surface of the anode

Methodology Applied

Scientific EffectReductive decomposition: Reduction

Implementation Method 2

The SEI is permeable for lithium ions and protects the electrolyte composition from direct contact with the anode and vice versa

Methodology Applied

Scientific EffectIon transport: Ion Repulsion/Attraction

Data Source

PatentUS10930974B2Electrolyte composition containing methyl 2-methyl-1,3-dioxolane-2-carboxylate, and electrochemical cells comprising the same

Publication Date: 2021.02.23 GOTION INC

AI summary

An electrolyte composition and an electrochemical cell including the electrolyte composition are disclosed, including: at least one aprotic organic solvent; at least one conducting salt; methyl-2-methyl-1,3-dioxolane-2-carboxylate; and optionally one or more additives. A use of methyl-2-methyl-1,3-dioxolane-2-carboxylate in an electrolyte composition for electrochemical cells is disclosed. An electrochemical cell is also disclosed, in which the electrochemical cell is a lithium battery.