Phase Stability and Kinetics of Topotactic Dual Ca2+–Na+ Ion Electrochemistry in NaSICON NaV2(PO4)3
Year: 2022
Type: article
Abstract: Recent reports of reversible calcium plating and stripping have rekindled interest in the development of Ca-ion batteries (CIBs) as next-generation energy storage devices. This technology has the potential to overcome the limitations of conventional Li-ion batteries, but CIBs are plagued by a paucity of suitable cathode materials. To date, NaSICON-structured NaV 2 (PO 4 ) 3 has been demonstrated as a successful cathode candidate, exhibiting reversible (de)intercalation of 0.6 mol Ca 2+ along with stable cycling performance. However, a complex multiphase mixture forms on discharge so the Ca-ion charge storage mechanism in the NaSICON framework is poorly understood. In this work, we report on an investigation of the structure and/or Na + /Ca 2+ environment(s) of a variety of chemically prepared NaSICON Ca x Na y V 2 (PO 4 ) 3 phases which were characterized using synchrotron XRD, SEM-EDS, 23 Na NMR, and TEM. Highly calciated CaV 2 (PO 4 ) 3, Ca 1.5 V 2 (PO 4 ) 3, and CaNaV 2 (PO 4 ) 3 phases can be prepared at high temperature, but─unlike Ca 0.6 NaV 2 (PO 4 ) 3 ─these materials are electrochemically inactive. To better understand the fundamental factors impacting successful Ca 2+ electrochemistry in this system, DFT was employed to examine the Ca x Na y V 2 (PO 4 ) 3 phase diagram and Ca 2+ diffusion mechanism. Theoretical insights show that phase separation into Na-rich and Ca-rich phases is a reason for the capacity limitation and demonstrate that Na + ions in the host materials assist the migration of neighboring Ca 2+ ions, enabling reversible electrochemistry in Ca x Na y V 2 (PO 4 ) 3 . This investigation of fundamental principles affecting reversible Ca 2+ (de)intercalation in Ca x Na y V 2 (PO 4 ) 3 allows for the development of design principles to enable the discovery of a variety of successful cathodes for CIBs.
Source: Chemistry of Materials
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
Funders: National Science Foundation, U.S. Department of Energy, National Energy Research Scientific Computing Center, Canada Research Chairs, Office of Science, Natural Sciences and Engineering Research Council of Canada, Division of Materials Research, Basic Energy Sciences, Argonne National Laboratory
Awards: G102163711, G107546177, G122673668, G1286236842, G1286251239, G1313983767, G1664757510, G1677143136, G2287611682, G2618837358, G262962599, G2638771445, G2710870262, G30714459, G3075337988, G3083819904, G419881185, G426311843, G42916606, G4501827968, G498139845, G5076365615, G5387317844, G650090426, G6652958823, XSEDE: eXtreme Science and Engineering Discovery Environment, G6848031779, G6918803902, G7583137537, G969889393, G993149817
OpenAlex ID: W4313367205