Layered Iron Vanadate as a High-Capacity Cathode Material for Nonaqueous Calcium-Ion Batteries

Abstract

Calcium-ion batteries represent a promising alternative to the current lithium-ion batteries. Nevertheless, calcium-ion intercalating materials in nonaqueous electrolytes are scarce, probably due to the difficulties in finding suitable host materials. Considering that research into calcium-ion batteries is in its infancy, discovering and characterizing new host materials would be critical to further development. Here, we demonstrate FeV3O9∙1.2H2O as a high-performance calcium-ion battery cathode material that delivers a reversible discharge capacity of 303 mAh g−1 with a good cycling stability and an average discharge voltage of ~2.6 V (vs. Ca/Ca2+). The material was synthesized via a facile co-precipitation method. Its reversible capacity is the highest among calcium-ion battery materials, and it is the first example of a material with a capacity much larger than that of conventional lithium-ion battery cathode materials. Bulk intercalation of calcium into the host lattice contributed predominantly to the total capacity at a lower rate, but became comparable to that due to surface adsorption at a higher rate. This stimulating discovery will lead to the development of new strategies for obtaining high energy density calcium-ion batteries.

CaV6O16·2.8H2O with Ca2+ Pillar and Water Lubrication as a High‐Rate and Long‐Life Cathode Material for Ca‐Ion Batteries

“…The percentage of capacitive contribution increases from 9.8% to 60.1% with the scan rate increases, indicating that the with the reported inorganic materials for CIBs in organic electrolytes. [3,14,15,17,18,21,[25][26][27][28][29][30][31][32][33][34][35][36] capacitive controlled charge storage becomes dominant as the scan rate increases, which makes CVO have excellent rate performance. The Ca 2+ diffusion kinetics in the CVO was studied by galvanostatic intermittent titration technique (GITT).…”

Poly(Anthraquinonyl Sulfide)/CNT Composites as High‐Rate‐Performance Cathodes for Nonaqueous Rechargeable Calcium‐Ion Batteries

“…This asymmetric redox peak behavior has also been observed in several other cathodes for Ca 2+ storage. [ 7c,12,26 ] However, there is no clear explanation for this phenomenon. Based on the reported literature, the reason might be the intercalation/extraction of Ca 2+ and Ca(TFSI) + that occurs in stages.…”

“…[ 6 ] Therefore, a three‐electrode system and active carbon as counter electrode are usually applied for CIBs. [ 7 ] Another challenge of CIBs is the lack of high‐performance electrode materials. Due to stronger electrostatic interaction between divalent Ca 2+ and hosting lattice than monovalent cations, Ca ions exhibit sluggish diffusion in inorganic crystals.…”

“…Due to stronger electrostatic interaction between divalent Ca 2+ and hosting lattice than monovalent cations, Ca ions exhibit sluggish diffusion in inorganic crystals. [ 8 ] In recent years, a number of inorganic cathode materials are reported for calcium storage, such as Mg 0.25 V 2 O 5 ∙H 2 O, [ 7c ] K 2 BaFe(CN) 6 , [ 9 ] Na‐doped NH 4 V 4 O 10 , [ 10 ] β ‐Ag 0.33 V 2 O 5 , [ 11 ] Na x MnFe(CN) 6 , [ 12 ] CaCo 2 O 4 , [ 13 ] VOPO 4 ∙2H 2 O, [ 14 ] NaV 2 (PO 4 ) 3 , [ 15 ] FePO 4 , [ 15 ] FeV 3 O 9 ∙1.2H 2 O, [ 7a ] Fe 4 [Fe(CN) 6 ] 3 , [ 16 ] Na 2 FePO 4 F [ 17 ] and K 0.5 V 2 O 5 . [ 7b ] Most of these materials show poor rate performance and cycle life.…”

“…[ 8 ] In recent years, a number of inorganic cathode materials are reported for calcium storage, such as Mg 0.25 V 2 O 5 ∙H 2 O, [ 7c ] K 2 BaFe(CN) 6 , [ 9 ] Na‐doped NH 4 V 4 O 10 , [ 10 ] β ‐Ag 0.33 V 2 O 5 , [ 11 ] Na x MnFe(CN) 6 , [ 12 ] CaCo 2 O 4 , [ 13 ] VOPO 4 ∙2H 2 O, [ 14 ] NaV 2 (PO 4 ) 3 , [ 15 ] FePO 4 , [ 15 ] FeV 3 O 9 ∙1.2H 2 O, [ 7a ] Fe 4 [Fe(CN) 6 ] 3 , [ 16 ] Na 2 FePO 4 F [ 17 ] and K 0.5 V 2 O 5 . [ 7b ] Most of these materials show poor rate performance and cycle life. Therefore, the exploitation of high‐performance electrode capable of reversible Ca 2+ ion storage is particularly important for the development of CIBs.…”