Low-temperature anode-free potassium metal batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Anode-free batteries offer higher energy densities but face challenges with reversible alkali metal plating/stripping, especially at low temperatures.
• Unstable solid-electrolyte interphase and dendrite growth hinder low-temperature performance in conventional anode-free systems.

Purpose of the Study:

• To develop a low-temperature anode-free potassium (K) metal non-aqueous battery with improved reversibility and stability.
• To investigate the use of Si-O-based additives for uniform K deposition at sub-zero temperatures.

Main Methods:

• Utilized polydimethylsiloxane (a Si-O-based additive) in a weak-solvation, low-concentration electrolyte (0.4 M KPF6 in DME).
• Investigated K||Cu cells to evaluate the Coulombic efficiency of K plating/stripping at -40°C.
• Assembled anode-free Cu||prepotassiated 3,4,9,10-perylene-tetracarboxylicacid-dianhydride full cells for performance testing.

Main Results:

• Achieved an average K plating/stripping Coulombic efficiency of 99.80% at -40°C due to an in situ formed potassiophilic interface.
• Demonstrated stable cycling in full cells with a high specific energy of 152 Wh kg⁻¹ at 0.2 C and -40°C.
• The Si-O-based additive effectively promoted uniform K deposition, suppressing dendrite growth.

Conclusions:

• The developed low-temperature anode-free K metal battery system shows significant promise for high-performance energy storage.
• The strategy of using Si-O-based additives in a specific electrolyte formulation is effective for enabling stable and efficient low-temperature operation.
• This work advances the feasibility of anode-free alkali metal batteries for practical applications in extreme environments.