A Redox-Active Organic Cation for Safer Metallic Lithium-Based Batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• High-energy-density lithium-based batteries face safety challenges, primarily dendrite formation and overcharging, leading to thermal runaway.
• Current safety measures often compromise battery performance or are insufficient for advanced lithium battery applications.

Purpose of the Study:

• To introduce trisaminocyclopropenium (TAC) as a novel, bi-functional electrolyte additive for enhanced safety in metallic lithium-based batteries.
• To investigate TAC's ability to suppress lithium dendrite growth and provide reversible overcharge protection.

Main Methods:

• Utilized TAC organic cations as an electrolyte additive in lithium-based battery systems.
• Investigated dendrite suppression via electrostatic shielding during lithium plating in Li|Li symmetric cells.
• Evaluated overcharge protection by monitoring cell voltage and cycling stability in LiFePO4/Li4Ti5O12 cells.

Main Results:

• TAC additive demonstrated effective suppression of lithium dendrite growth, leading to a two-fold increase in cycle life (300 h at 1 mA cm⁻²) in symmetric cells.
• Redox-active TAC provided reversible overcharge protection, enabling 117 cycles (~1640 h) with 100% overcharge in a LiFePO4/Li4Ti5O12 cell.
• TAC cations formed a protective electrostatic shield around lithium plating protrusions, promoting uniform deposition.

Conclusions:

• Trisaminocyclopropenium (TAC) organic cations are a promising bi-functional additive for significantly improving the safety of high-energy-density lithium-based batteries.
• The findings highlight the potential of organic cations in developing safer and more reliable energy storage solutions.
• TAC offers a dual mechanism for enhanced safety, addressing both dendrite formation and overcharging issues.