Cation-Disordered O3-Na_0.8Ni_0.6Sb_0.4O₂ Cathode for High-Voltage Sodium-Ion Batteries

Abstract

O3-type sodium-layered oxides (such as antimony-based O3 structures) have been suggested as one of the most fascinating cathode materials for sodium-ion batteries (SIBs). Honeycomb-ordered antimony-based O3 structures, however, unsatisfactorily exhibit complex phase transitions and sluggish Na+ kinetics during cycling. Herein, we prepared a completely cationic-disordered O3-type Na0.8Ni0.6Sb0.4O2 compound by composition regulation for SIBs. Surprisingly, the measured redox potentials for typical O3–P3 phase transition are located at 3.4 V. Operando X-ray diffraction confirms a reversible phase transition process from the O3 to P3 structure accompanied with a very small volume change (1.0%) upon sodium extraction and insertion. The low activation barrier energy of 400 meV and the fast Na+ migration of 10–11 cm2·s–1 are further obtained by first-principles calculations and galvanostatic intermittent titration technique, respectively. As a result, the O3-Na0.8Ni0.6Sb0.4O2 cathode displays a reversible capacity of 106 mA h g–1 at 0.1C (12 mA g–1), smooth charge–discharge curves, and a high average working voltage of 3.5 V during battery cycling. The results highlight the importance of searching for a new O3-type structure with cation-disordering and high working voltage for realizing high energy SIBs.

A High-Rate, Durable Cathode for Sodium-Ion Batteries: Sb-Doped O3-Type Ni/Mn-Based Layered Oxides

“…Besides, since the XPS result shows the surface oxidation states of each element and the XANES result indicates the overall bulk oxidation number, by combining both XPS and XANES results, it can be further determined that the Sb dopants homogeneously dispersed on the NaNMS particles. The previously reported Sb ions in O3-Na­(Ni 2/3 Sb 1/3 )­O 2 , , O3-Na 0.8 Ni 0.6 Sb 0.4 O 2 , , and O3-Na 0.9 Cr 0.95 Sb 0.05 O 2 are pentavalent. However, both Sb 3+ and Sb 5+ are present in the Sb-substituted Ni/Mn-based layered oxide cathodes.…”

Unraveling the Synergistic Effect of Mg and Ti Codoping to Realize an Ordered Structure and Excellent Performance for Sodium-Ion Batteries

“…However, the development and identification of advanced cathode materials are still very challenging. Among the families of the well-known cathode materials to date, sodium layered transition-metal (TM) oxides (Na x TMO 2 ) have been intensively studied considering their great structural diversities such as P2, O3, and P3, attractive electrochemical properties, and facile preparation. − However, different from their Li-based oxide counterparts, the insertion/extraction of larger Na + (1.02 Å) than Li + (0.7 Å) can cause severe volume variation, Na + /vacancy ordering, and a series of phase transformations of layered oxide cathodes upon cycling, resulting in severe structural distortion, even collapse, and consequently remarkable cycling capacity fading. − …”

Low-Cost Al-Doped Layered Cathodes with Improved Electrochemical Performance for Rechargeable Sodium-Ion Batteries

“…In the past few years, sodium-ion batteries (SIBs) have become popular in academia owing to the abundance and cost-effectiveness of Na resources. − Similar to lithium-ion batteries, SIBs are also “rocking-chair batteries” with a unit-priced electrochemical reaction control and thus considered a candidate for next-generation sustainable development. − However, the large ionic size of Na + (1.02 Å) usually results in unsatisfactory reaction kinetics and irreversible phase transitions of sodium electrode materials. Meanwhile, a cathode is seen as the key to determining the cost of SIBs and has a critical influence on the electrochemical properties of the entire battery. − Therefore, great efforts have been devoted to exploring suitable Na + intercalation hosts. At present, layered oxides, polyanion compounds, and Prussian blue analogues have been widely tested as Na cathode materials; among the layered oxides, Na y TMO 2 (TM = Co, Ni, Fe, Mn, Cu, etc.)…”