Ultrafast Hopping Transfer Enables High-Anion Conduction.

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Dual-ion batteries (DIBs) offer high voltage (>5.0 V), safety, and cost-effectiveness due to anion intercalation chemistry.
• Anion transport mechanisms in DIBs are underexplored, unlike cation diffusion in conventional batteries.

Purpose of the Study:

• To investigate the charge transport behavior of anions in DIBs.
• To understand how ionic radius and solvation dynamics influence anion diffusion kinetics.
• To optimize electrolyte and separator design for enhanced DIB performance.

Main Methods:

• Identification of an ultrafast anion-hopping mechanism.
• Engineering of localized high-concentration electrolytes (LHCE) to reduce anion-solvent affinity.
• Utilizing wettable cellulose separators to suppress solvent co-intercalation.
• Construction of an inorganic-rich cathode-electrolyte interphase (CEI).

Main Results:

• An ultrafast anion-hopping mechanism was identified, driven by large ionic radius and charge delocalization.
• The developed LHCE and cellulose separator strategy effectively suppressed solvent co-intercalation.
• Rapid anion desolvation and high-rate kinetics were achieved, leading to a reversible capacity of 69.10 mAh g^-1 at 200C.
• The DIBs demonstrated exceptional cycle life, exceeding 50,000 cycles.

Conclusions:

• The study elucidates the anion transport mechanism in DIBs, highlighting the role of solvation microenvironment.
• The synergistic strategy of LHCE and cellulose separators enables high-rate anion intercalation.
• Findings provide insights for designing advanced electrolytes for high-voltage, fast-charging DIBs and other energy storage systems.