High-Voltage Stabilization of O3-Type Layered Oxide for Sodium-Ion Batteries by Simultaneous Tin Dual Modification

13 pags., 6 figs.
O3-type layered oxide materials are considered to be a highly suitable cathode for sodium-ion batteries (NIBs) due to their appreciable specific capacity and energy density. However, rapid capacity fading caused by serious structural changes and interfacial degradation hampers their use. A novel Sn-modified O3-type layered NaNi1/3Fe1/3Mn1/3O2 cathode is presented, with improved high-voltage stability through simultaneous bulk Sn doping and surface coating in a scalable one-step process. The bulk substitution of Sn4+ stabilizes the crystal structure by alleviating the irreversible phase transition and lattice structure degradation and increases the observed average voltage. In the meantime, the nanolayer Sn/Na/O composite on the surface effectively inhibits surface parasitic reactions and improves the interfacial stability during cycling. A series of Sn-modified materials are reported. An 8%-Sn-modified NaNi1/3Fe1/3Mn1/3O2 cathode exhibits a doubling in capacity retention increase after 150 cycles in the wide voltage range of 2.0-4.1 V vs Na/Na+ compared to none, and 81% capacity retention is observed after 200 cycles in a full cell vs hard carbon. This work offers a facile process to simultaneously stabilize the bulk structure and interface for the O3-type layered cathodes for sodium-ion batteries and raises the possibility of similar effective strategies to be employed for other energy storage materials.
The University of Birmingham is thanked for providing doctoral funding. EK, PRS, DR, and DG acknowledge the Faraday Institution (EP/S003053/1) and its Recycling of LiIon Batteries (ReLiB) project (FIRG005). EK, BD, PRS acknowledge CATMAT, (FIRG016). EK, PRS, and LC acknowledge SIMBA, which has received funding from the European Union’s Horizon 2020 research and innovation program under Grant Agreement no. 883753. Grant RTI2018-095303-B-C51 funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe” and grant S2018-NMT-4321 funded by the Comunidad de Madrid and by “ERDF A way of making Europe” are gratefully acknowledged. The authors also would like to thank EPSRC National Facility for XPS (“HarwellXPS”) for the XPS tests, and Dr John Nutter (The Henry Royce Institute and Department of Material Science and Engineering, The University of Sheffield, S1 3JD) for providing the TEM testing support