Dendrite formation in Li-metal anodes: an atomistic molecular dynamics study

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• Lithium-metal anodes offer high capacity for advanced batteries but suffer from dendrite formation and electrolyte reactivity.
• Solid electrolyte interfaces (SEI) are critical for stabilizing lithium metal anodes.

Purpose of the Study:

• To investigate the effect of a cracked LiF SEI on lithium dendrite formation during battery charging.
• To understand how temperature and charging rate influence dendrite growth in a model nanobattery.

Main Methods:

• Classical molecular dynamics simulations were employed.
• A model nanobattery with a cracked LiF SEI and liquid electrolyte (1 M LiPF6 in ethylene carbonate) was simulated.
• Three charging protocols were tested: constant current, pulse train, and constant ion flux.

Main Results:

• A cracked SEI significantly promotes and directs lithium dendrite formation between 325 K and 410.7 K.
• Dendrite formation is more pronounced at lower temperatures (325 K) within this range.
• Higher charging rates (2.2C) lead to more lithium dendrite formation than lower rates (1.6C).

Conclusions:

• The presence of cracks in the LiF SEI is a key factor in accelerating lithium dendrite growth.
• Optimizing charging rates and operating temperatures can mitigate dendrite formation, enhancing battery safety.
• This research provides insights for designing stable lithium metal anodes.