Lithium Metal Battery Electrolyte for Uniform Lithium Nucleation
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Solution Overview
Problem
Lithium metal batteries face issues with lithium dendrite formation at the negative electrode during cycling, leading to safety threats and reduced cycling performance.
Innovation Solution
An electrolyte additive with a structure of R-M-X is used, where R includes a hydrocarbon group, M is a metal with a higher standard electrode potential than Li, and X can form an intermetallic compound or alloy solid solution with Li, forming a lithiophilic layer on the negative electrode current collector, promoting uniform lithium nucleation and reducing dendrite formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolytes are used in lithium metal batteries, then the battery structure is simple and easy to manufacture, but lithium dendrite formation occurs at the negative electrode during cycling
Solution Approach 1:
The patent introduces an electrolyte additive as an intermediary substance that mediates between the lithium ions and the negative electrode. The additive decomposes during initial charging to form a lithiophilic layer (intermediary layer) on the electrode surface, which then serves as a mediator for subsequent lithium deposition, preventing direct contact between lithium ions and the base electrode material that would cause dendrite formation.
Solution Approach 2:
The electrolyte additive performs preliminary action by decomposing during the initial charging process (formation cycle) to create a lithiophilic layer on the negative electrode surface before actual lithium cycling begins. This pre-formed layer prepares the electrode surface to promote uniform lithium nucleation and deposition in subsequent cycles, preventing dendrite formation from the outset.
2Reliability
If a lithiophilic layer is formed on the negative electrode surface, then uniform lithium nucleation is promoted and dendrite formation is suppressed, but the electrolyte composition becomes more complex
Solution Approach 1:
The patent changes the chemical composition parameter of the electrolyte by adding specific substances (such as organometallic compounds with R-M-X structure where M is Mg, Al, Mn, or Zn). This parameter change enables the formation of a lithiophilic layer that promotes uniform lithium deposition, accepting the trade-off of increased electrolyte complexity for improved deposition uniformity and dendrite suppression.
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 lithiophilic layer enhances lithium deposition uniformity, improving battery performance by suppressing dendrite formation and increasing cycling stability.
Implementation Method 1
the standard electrode potential of M is higher than that of Li, allowing M to gain electrons preferentially over Li and deposit before Li, forming a lithiophilic layer on a surface of an anode current collector
Implementation Method 2
M is capable of forming an intermetallic compound or an alloy solid solution with Li
Implementation Method 3
M is capable of forming an intermetallic compound or an alloy solid solution with Li
Implementation Method 4
an overpotential for lithium ions to gain electrons from M is lower than an overpotential to gain electrons from the current collector
Data Source
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AI summary
An electrolyte, a lithium metal battery and a preparation method thereof, and an electric apparatus are provided, related to the field of batteries. The electrolyte includes a lithium salt, an organic solvent, and an electrolyte additive, and a structure of the electrolyte additive includes R-M-X, where R includes a hydrocarbon group, M includes a metal with a standard electrode potential higher than a standard electrode potential of Li, X includes anions or a hydrocarbon group, and M is capable of forming an intermetallic compound or an alloy solid solution with Li. The lithium metal battery includes a negative electrode. The negative electrode includes a negative electrode current collector and a lithiophilic layer covering a surface of the negative electrode current collector. The lithiophilic layer includes M, and M includes the metal with a standard electrode potential higher than the standard electrode potential of Li and capable of forming an intermetallic compound or an alloy solid solution with Li. The electrolyte can improve lithiophilicity of the negative electrode surface, promoting uniform lithium nucleation, and improving cycling performance of the lithium metal battery.