Ionic Liquid Electrolyte Additive for Lithium Dendrite Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium metal batteries face issues with dendritic lithium growth, leading to internal short circuits, safety risks, and reduced life characteristics due to the high reactivity of lithium with the electrolyte and uneven lithium ion flow, which disrupts the solid electrolyte interphase film.
Innovation Solution
An ionic liquid compound with a symmetrical cation structure and low standard reduction potential is used as an electrolyte additive, forming a uniform protective layer on the lithium tip to suppress dendritic growth and promote uniform lithium growth, minimizing self-aggregation and enhancing the stability of the solid electrolyte interphase film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium metal is used as anode active material to achieve high energy density, then capacity increases, but dendritic lithium growth occurs leading to safety problems and reduced life
Solution Approach 1:
The patent introduces an ionic liquid compound as an intermediary substance that forms a protective film between the lithium metal anode and the electrolyte. This intermediary layer prevents direct contact and harmful interactions while allowing lithium ion transport, thereby suppressing dendritic growth and improving safety without sacrificing capacity
Solution Approach 2:
The patent modifies the chemical composition parameters of the electrolyte by adding specific ionic liquid compounds with particular molecular structures (containing fluorine atoms and specific cation-anion combinations). These parameter changes alter the interfacial properties and reaction characteristics, leading to suppressed dendritic growth while maintaining high capacity
2Quantity of substance
If lithium metal is used as anode active material to achieve high energy density, then capacity increases, but life characteristics are reduced due to continuous irreversible reactions
Solution Approach 1:
The ionic liquid compound acts as a protective intermediary that forms a stable interface layer, preventing continuous irreversible reactions between lithium metal and the electrolyte. This mediator maintains the integrity of the solid electrolyte interphase film throughout charge-discharge cycles, thereby extending battery life
Solution Approach 2:
The ionic liquid compound preliminarily forms a protective film on the lithium metal surface before harmful irreversible reactions can occur. This preliminary protective action prevents subsequent degradation and extends the operational life of the battery
3Reliability
If ionic liquid compound with high amphiphilicity is used as additive to suppress dendritic growth, then protective layer forms, but self-aggregation occurs leading to incomplete coverage
Solution Approach 1:
The patent carefully adjusts the molecular structure parameters of the ionic liquid compound, specifically selecting cations and anions with appropriate sizes and chemical properties. This parameter optimization reduces excessive amphiphilicity and self-aggregation tendency while maintaining effective protective film formation capability
Solution Approach 2:
The patent uses composite ionic liquid compounds comprising specific cation-anion pairs (such as pyrrolidinium-based cations with fluorine-containing anions) that exhibit synergistic effects. The composite structure balances amphiphilicity and reduces self-aggregation, enabling complete and uniform protective layer coverage
4Speed
If lithium ions concentrate around lithium tip due to strong electric field, then dendritic growth occurs, but uniform lithium growth is needed for battery performance
Solution Approach 1:
The ionic liquid compound forms an intermediary protective film on the lithium tip surface that moderates the strong electric field concentration. This intermediary layer redistributes the electric field and guides lithium ion flow more uniformly, preventing concentrated deposition and dendritic growth while maintaining high deposition speed
Solution Approach 2:
The patent applies the ionic liquid additive that creates locally different properties at the lithium tip surface versus the bulk electrolyte. The protective film provides local field modulation and controlled ion transport properties, achieving uniform lithium growth across the anode surface
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 additive effectively suppresses dendritic lithium growth, improving the safety and life characteristics of lithium metal batteries by preventing short circuits and maintaining high capacity, while ensuring stable operation and long-term performance.
Implementation Method 1
The cations of the ionic liquid compound can be adsorbed on the surface of the lithium tip to form a protective layer, thereby repulsing lithium ions around the lithium tip
Implementation Method 2
As previously proposed ionic liquid compounds have high amphiphilicity, they show a strong propensity of being self-aggregated around the lithium tip
Implementation Method 3
forming a uniform protective layer on the lithium tip to suppress dendritic growth and promote uniform lithium growth
Data Source
AI summary
An additive for a secondary battery and a lithium metal battery including the same are provided. The additive comprises an ionic liquid compound that includes a cation and an anion and is in a liquid state at an atmospheric pressure and at a temperature of 100° C. or less. The cation has a standard reduction potential lower than that of lithium cation (Li+) based on a standard hydrogen electrode (SHE) and has a structure in which an even number of aliphatic hydrocarbon groups having 3 or more carbon atoms identical to each other are bonded to a central element of the cation such that the cation has a symmetrical structure based on the central element. The additive is capable of suppressing dendritic lithium growth and induce uniform lithium growth on lithium metal thin films, thereby improving performance and life of the lithium metal battery.