Phase Stability and Kinetics of Topotactic Dual Ca2+–Na+ Ion Electrochemistry in NaSICON NaV2(PO4)3
- University of Waterloo, ON (Canada); Argonne National Laboratory (ANL), Argonne, IL (United States). Joint Center for Energy Storage Research (JCESR)
- University of California, Berkeley, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). Materials Sciences Division; Argonne National Laboratory (ANL), Argonne, IL (United States). Joint Center for Energy Storage Research (JCESR)
- Argonne National Laboratory (ANL), Argonne, IL (United States). Joint Center for Energy Storage Research (JCESR); Argonne National Laboratory (ANL), Argonne, IL (United States). Chemical Sciences and Engineering Division
- Argonne National Laboratory (ANL), Argonne, IL (United States). Joint Center for Energy Storage Research (JCESR); Argonne National Laboratory (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
- Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
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 NaV2(PO4)3 has been demonstrated as a successful cathode candidate, exhibiting reversible (de)intercalation of 0.6 mol Ca2+ 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. Here in this work, we report on an investigation of the structure and/or Na+/Ca2+ environment(s) of a variety of chemically prepared NaSICON CaxNayV2(PO4)3 phases which were characterized using synchrotron XRD, SEM-EDS, 23Na NMR, and TEM. Highly calciated CaV2(PO4)3, Ca1.5V2(PO4)3, and CaNaV2(PO4)3 phases can be prepared at high temperature, but -unlike Ca0.6NaV2(PO4)3-these materials are electrochemically inactive. To better understand the fundamental factors impacting successful Ca2+ electrochemistry in this system, DFT was employed to examine the CaxNayV2(PO4)3 phase diagram and Ca2+ 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 Ca2+ ions, enabling reversible electrochemistry in CaxNayV2(PO4)3. This investigation of fundamental principles affecting reversible Ca2+ (de)intercalation in CaxNayV2(PO4)3 allows for the development of design principles to enable the discovery of a variety of successful cathodes for CIBs.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES); National Science Foundation (NSF)
- Grant/Contract Number:
- AC02-06CH11357; AC02-05CH11231; ACI1053575
- OSTI ID:
- 1960511
- Journal Information:
- Chemistry of Materials, Vol. 35, Issue 2; ISSN 0897-4756
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Similar Records
High-Voltage Phosphate Cathodes for Rechargeable Ca-Ion Batteries
Optimization of the compositions of polyanionic sodium-ion battery cathode NaFe2-xVx(PO4)(SO4)2