Anion-Blocking and Multipath-Conducting Interfaces Enable Long-Life Room-Temperature Ester-Based Ca-Metal Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Ester-based electrolytes are common in lithium storage but problematic for calcium-metal (Ca-metal) batteries.
• Ca-metal batteries face challenges with pure calcium salt ester electrolytes due to anode passivation by anion corrosion.
• Stable and fast kinetics interfaces are crucial for durable room-temperature Ca-metal battery operation.

Purpose of the Study:

• To demonstrate the first long-life pure calcium salt ester-based Ca-metal battery.
• To overcome the limitations of anode passivation in Ca-metal batteries using ester electrolytes.
• To engineer stable and fast kinetics interfaces for improved Ca-metal battery performance.

Main Methods:

• Utilized a biomass-derived carbon cathode.
• Engineered Ca-metal interfaces with calcium-(Ca-)/iron-(Fe-)based inorganic salts and core-shell iron (Fe) nanocrystals.
• Incorporated carbon-nitrogen (C─N) organics as an anion-blocking medium.

Main Results:

• Achieved >500 cycles with 85.4% capacity retention at 25 mA g^-1 in pure calcium salt ester-based Ca-metal batteries.
• Demonstrated a low Ca-metal deposition overpotential of 0.53 V (vs Ca/Ca²⁺).
• Exhibited stable Ca-metal deposition/stripping for >950 hours with 6 mAh cm^-2 interface-stable deposit capacity.

Conclusions:

• Successfully developed the first long-life pure calcium salt ester-based Ca-metal battery.
• Engineered interfaces with diverse interphases and anion-blocking capabilities enhance kinetics and reversibility.
• This work presents a viable interface engineering strategy for ester-based Ca-metal batteries.