Li2C2, a High-Capacity Cathode Material for Lithium Ion Batteries.

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Lithium carbide (Li2C2) possesses the highest theoretical specific capacity among lithium-containing cathode materials for lithium-ion batteries.
• Alkaline earth metal carbides are explored for their potential in energy storage applications.

Purpose of the Study:

• To investigate the feasibility of using Li2C2 as a cathode material in lithium-ion batteries.
• To understand the electrochemical behavior and structural transformations of Li2C2 during lithium extraction.

Main Methods:

• First-principles molecular dynamics (FPMD) simulations to study structural changes.
• Density functional theory (DFT) calculations to analyze electronic properties.
• Arrhenius fitting to assess conductivity.

Main Results:

• Demonstrated feasibility of extracting at least half the lithium from Li2C2.
• Achieved a reversible specific capacity of 700 mA h g−1.
• Observed rotation of C≡C bonds to form C4 chains during lithium extraction.
• Identified low electronic and ionic conductivity as reasons for charge-discharge potential gaps.

Conclusions:

• Li2C2 is a viable high-capacity cathode material for secondary batteries.
• Alkali and alkaline earth metal carbides represent a promising class of electrode materials for high-capacity energy storage.
• Further research into improving conductivity is warranted for practical applications.