Abstract
Affordable sodium ion batteries hold great promise for revolutionizing stationary energy storage technologies. Sodium layered cathode materials are usually multicomponent transition metal (TM) oxides and each TM plays a unique role in the operating cathode chemistry, e.g., redox activity, structural stabilization. Engineering the three-dimensional (3D) distribution of TM cations in individual cathode particles can take advantage of a depth-dependent charging mechanism and enable a path towards tuning local TM-O chemical environments and building resilience against cathode-electrolyte interfacial reactions that are responsible for capacity fading, voltage decay and safety hazards. In this study, we create 3D compositional heterogeneity in a ternary and biphasic (O3-P3) sodium layered cathode material (Na0.9Cu0.2Fe0.28Mn0.52O2). The cells containing this material deliver stable voltage profiles, and discharge capacities of 125 mA h g-1 at C/10 with almost no capacity fading after 100 cycles and 75 mA h g-1 at 1C with negligible capacity fading after 200 cycles. The direct performance comparison shows that this material outperforms other materials with similar global compositions but different mesoscale chemical distributions. Synchrotron X-ray spectroscopy/imaging and density functional theory studies reveal depth-dependent chemical environments due to changes to factors such as charge compensation and strength of orbital hybridization. Finally, 3D spectroscopic tomography illuminates the path towards optimizing multicomponent sodium layered cathode materials, to prevent the migration of TMs upon prolonged cycling. The study reports an inaugural effort of multifaceted and counterintuitive investigation of sodium layered cathode materials and strongly implies that there is plenty of room at the bottom by tuning nano/meso scale chemical distributions for stable cathode chemistry.
Original language | English |
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Pages (from-to) | 2496-2508 |
Number of pages | 13 |
Journal | Energy and Environmental Science |
Volume | 11 |
Issue number | 9 |
DOIs | |
State | Published - Sep 2018 |
Externally published | Yes |
Funding
The work was supported by Virginia Tech Department of Chemistry startup funds. The Stanford Synchrotron Radiation Lightsource, a Directorate of SLAC National Accelerator Laboratory and an Office of Science User Facility is operated for the US Department of Energy Office of Science by Stanford University. Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, is supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515. M. M. R, Y. X., Y. L. and F. L. thank D. Van Campen and Dave Day for valuable discussions and their engineering support for experiments at beamline 6-2C of SSRL. The authors acknowledge Special Program for Applied Research on Super Computation of the NSFC-Guangdong Joint Fund (the second phase) under Grant No. U1501501. The authors also acknowledge Stephen McCartney for his assistance in SEM at the Nanoscale Characterization and Fabrication Laboratory at Virginia Tech. The authors would further like to acknowledge Dr Tom Staley for his technical assistance with XRD in Material Science and Engineering at Virginia Tech. This research used resources of the Advanced Photon Source, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science by Argonne National Laboratory, and was supported by the U.S. DOE under Contract No. DE-AC02-06CH11357, and the Canadian Light Source and its funding partners. The authors acknowledge the technical support from Dr Ryan Davis at Beamline 4-1 of SSRL.
Funders | Funder number |
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Office of Basic Energy Sciences | |
Special Program for Applied Research on Super Computation of the NSFC-Guangdong Joint Fund | |
U.S. DOE | |
US Department of Energy | |
Virginia Tech Department of Chemistry Startup Funds | |
U.S. Department of Energy | |
Stanford University | |
Office of Science | |
Argonne National Laboratory | |
Canadian Light Source | |
National Natural Science Foundation of China | U1501501 |