Abstract
Lithium spinels (LiMM’O4) are an important class of mixed-cation materials that have found uses in batteries, catalysis, and optics. Postspinels are a series of related framework structures with the AMM’O4 host composition that are formed with larger A-site cations, typically under high pressure. Postspinels have one-dimensional tunnel structures with pores that are larger than those in spinel and triangular in cross-section, but they are relatively unexplored as intercalation electrodes. While lithium postspinels have been previously found to be thermodynamically stable only at high pressures, we have identified a synthetic pathway that produces the lithium-containing materials at ambient pressure using an ion-exchange process from the corresponding sodium postspinels. Here, we report the synthesis and a survey of the electrochemical properties of 10 new lithium CaFe2O4-type postspinel compounds where M = Mn3+, V3+, Cr3+, Rh3+, Fe2+, Mg2+, Co2+ and M’ = Ti4+ and/or Sn4+. Although complete delithiation is not achieved during electrochemical cycling, many of the lithium postspinels have substantial charge storage capacity in Li battery cells owing to the ability of the large framework tunnels to accommodate more than one lithium ion per formula unit. Multiple redox couples are accessed for LiMnSnO4, Li0.96Mn0.96Sn1.04-xTixO4, Li0.96V0.96Ti1.04O4, Li0.96Cr0.96Ti1.04O4, and LiFe0.5Ti1.5O4. Compositions with moderate or poor lithium cyclability are also discussed for comparison. Redox mechanisms and trends are identified by comparing this new redox-active framework to related spinels, ramsdellites, and ‘Na0.44MnO2’ structures, and from density functional theory (DFT) electronic structures. Operando diffraction shows complex structural responses to lithium insertion and extraction in this postspinel framework. A DFT framework was proposed to identify promising lithium postspinel phases that could be accessed metastably under ambient pressure conditions and to assess their stability to lithium insertion and extraction. This work suggests that CaFe2O4-type hosts are a promising new class of lithium-ion energy storage materials.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 4616-4630 |
| Number of pages | 15 |
| Journal | Chemistry of Materials |
| Volume | 36 |
| Issue number | 9 |
| DOIs | |
| State | Published - May 14 2024 |
Funding
This work was supported by the Joint Center for Energy Storage Research (JCESR), an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences. Use of the Advanced Photon Source at Argonne National Laboratory was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. This work made use of the Jerome B. Cohen X-ray Diffraction Facility supported by the MRSEC program of the National Science Foundation (DMR-1720139) at the Materials Research Center of Northwestern University and the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-2025633). This work made use of the IMSERC NMR facilities at Northwestern University, which have received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-2025633), International Institute of Nanotechnology, and Northwestern University. This research used resources of the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility located at Lawrence Berkeley National Laboratory, operated under Contract No. DE-AC02-05CH11231. Computational resources were also provided by the Extreme Science and Engineering Discovery Environment (XSEDE) resource Stampede2 through allocation TG-DMR970008S, which is supported by the National Science Foundation grant number ACI1053575.
ASJC Scopus subject areas
- General Chemistry
- General Chemical Engineering
- Materials Chemistry
