Abstract
High-entropy (HE) ceramics, by analogy with HE metallic alloys, are an emerging class of solid solutions composed of a large number of species. These materials offer the benefit of large compositional flexibility and can be used in a wide variety of applications, including thermoelectrics, catalysts, superionic conductors and battery electrodes. We show here that the HE concept can lead to very substantial improvements in performance in battery cathodes. Among lithium-ion cathodes, cation-disordered rocksalt (DRX)-type materials are an ideal platform within which to design HE materials because of their demonstrated chemical flexibility. By comparing a group of DRX cathodes containing two, four or six transition metal (TM) species, we show that short-range order systematically decreases, whereas energy density and rate capability systematically increase, as more TM cation species are mixed together, despite the total metal content remaining fixed. A DRX cathode with six TM species achieves 307 mAh g−1 (955 Wh kg−1) at a low rate (20 mA g−1), and retains more than 170 mAh g−1 when cycling at a high rate of 2,000 mA g−1. To facilitate further design in this HE DRX space, we also present a compatibility analysis of 23 different TM ions, and successfully synthesize a phase-pure HE DRX compound containing 12 TM species as a proof of concept.
| Original language | English |
|---|---|
| Pages (from-to) | 214-221 |
| Number of pages | 8 |
| Journal | Nature Materials |
| Volume | 20 |
| Issue number | 2 |
| DOIs | |
| State | Published - Feb 2021 |
Funding
This work was supported by Umicore Specialty Oxides and Chemicals, the Assistant Secretary for Energy Efficiency and Renewable Energy, Vehicle Technologies Office of the US Department of Energy (DOE) under contract no. DEAC02-05CH11231, under the Advanced Battery Materials Research (BMR) Program. Work at the Molecular Foundry was supported by the Office of Science and Office of Basic Energy Sciences of the US DOE under contract no. DE-AC02-05CH11231. The NMR experimental work reported here made use of the shared facilities of the UCSB MRSEC (NSF DMR 1720256), a member of the Material Research Facilities Network. This research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. This research used resources from beamline 28-ID of the National Synchrotron Light Source II, a US DOE Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under contract no. DE-SC0012704. Work at the Advanced Light Source is supported by the US DOE Office of Science User Facility under contract no. DE-AC02-05CH11231. This research used resources of the Advanced Photon Source, an Office of Science User Facility operated for the US DOE Office of Science by Argonne National Laboratory, and was supported by the US DOE under contract no. DE-AC02-06CH11357. The computational analysis was performed using computational resources sponsored by the US DOE Office of Energy Efficiency and Renewable Energy and located at the National Renewable Energy Laboratory, and computational resources were provided by Extreme Science and Engineering Discovery Environment (XSEDE), which was supported by National Science Foundation grant no. ACI1053575, as well as the National Energy Research Scientific Computing Center (NERSC), a DOE Office of Science User Facility supported by the Office of Science and the US DOE under contract no. DE-AC02-05CH11231. The authors thank J. Liu for help with the neutron diffraction measurements.