Current Status and Challenges of Calcium Metal Batteries

Abstract

Ca‐metal batteries, one of the promising advanced energy storage devices, have received significant development in the last few years. However, challenges still exist in efficient and cost‐effective Ca‐metal utilization, fast Ca‐ion transport and diffusion, and high energy density and stable‐cycling Ca‐storage. Herein, by cross‐checking most relevant literature reported previously, an intuitive depiction for state‐of‐the‐art Ca‐metal batteries, including collectors, electrolytes, and cathode materials, is presented from a voltage‐capacity‐efficiency's view, which facilitates reasonable comparisons from related fields. The performance of most cathode materials and calcium‐metal electrodes in various electrolytes reported previously is comprehensively reviewed, as well as interphases and collectors. The strong and weak points of various electrolytes are discussed, and relevant challenges are pointed out. Recent breakthroughs in electrolyte and interphase engineering are emphasized. Finally, potential development directions for Ca‐metal and electrolytes, as well as some future prospects for cathode materials, are rationally predicted.

Lithium-Free Batteries: Needs and Challenges

“…Ca−air battery technology is still in its infancy today, with the highly researched positive electrode materials being V 2 O 5 and Prussian Blue. 17,46,47 Many research groups have become more interested in zincion batteries (ZIBs), which comprise a Zn metal anode, a Zncontaining electrolyte, and cathodes for storing Zn ions. Because of the wide range of potential electrolytes available, including both aqueous and nonaqueous electrolytes, the higher redox potential of zinc, which allows the battery to operate in aqueous electrolytes, and the improved safety and reduced toxicity of ZIBs, the battery has become increasingly popular.…”

“…(b) Theoretical specific capacities for Li and Li-free metal anodes. Image reprinted with permission from ref . Copyright 2021 American Chemical Society.…”

“…(a) Scheme of a calcium battery cell, consisting of a calcium metal anode and intercalation cathode. Reprinted from ref . Copyright 2021 American Chemical Society.…”

“…There is a need to improve the performance of Ca anodes in solid electrolyte interphase (SEI)-forming electrolytes to generate higher voltage and energy density. Ca–air battery technology is still in its infancy today, with the highly researched positive electrode materials being V 2 O 5 and Prussian Blue. ,, …”

Vinylimidazole-Based Polymer Electrolytes with Superior Conductivity and Promising Electrochemical Performance for Calcium Batteries

“…For reference, cycling overpotentials reported with recent Ca 2+ -conducting liquid electrolyte systems are in the range of 0.1 to 1.0 V with lower overpotentials attributable to the Ca­[B­(hfip)] 2 salt. The reader is referred to recent review articles for detailed information on the state-of-the-art. , An unstable interface at the working electrode surface and effects arising from the complex ion-pair formation (aggregates) at higher salt concentrations can also contribute to high overpotentials. Noise in the plateaus during galvanostatic cycling may also originate from localized current densities due to irregularities on the surface of the working electrode.…”