Deciphering an Abnormal Layered‐Tunnel Heterostructure Induced by Chemical Substitution for the Sodium Oxide Cathode

Abstract

Demands for large-scale energy storage systems have driven the development of layered transition-metal oxide cathodes for room-temperature rechargeable sodium ion batteries (SIBs). Now,a na bnormal layered-tunnel heterostructure Na 0.44 Co 0.1 Mn 0.9 O 2 cathode material induced by chemical element substitution is reported. By virtue of beneficial synergistic effects,t his layered-tunnel electrode shows outstanding electrochemical performance in sodium half-cell system and excellent compatibility with hardc arbon anode in sodium full-cell system. The underlying formation process,c harge compensation mechanism, phase transition, and sodium-ion storage electrochemistry are clearly articulated and confirmed through combined analyses of in situ highenergy X-rayd iffraction and ex situ X-ray absorption spectroscopya sw ell as operando X-rayd iffraction. This crystal structure engineering regulation strategy offers af uture outlook into advanced cathode materials for SIBs.

Lithium‐Substituted Tunnel/Spinel Heterostructured Cathode Material for High‐Performance Sodium‐Ion Batteries

“…When the current density returns to 0.5 C, the maximum discharge capacity of the [NL]MO electrode is recovered to 123.0 mA h g –1 , due to the activation of spinel LiMn 2 O 4 . Remarkably, compared with other cathode materials incorporating the tunnel‐type Na 0.44 MnO 2 and its analogs, [ 12–14,16–19,23,29,41–47 ] the [NL][ML]O composite achieves the highest rate capability; refer to Figure 3d.…”

“…[ 12 ] Although the unique tunnel structure prevents the formation of undesirable multiphases during sodiation and desodiation, poor cycle stability and low capacity at high currents, caused by the Jahn–Teller (JT) distortion of Mn 3+ in MnO 6 , hinder the commercial application of Na 0.44 MnO 2 . [ 13,14 ] In order to address these limitations and improve its electrochemical kinetics, research has focused on morphological design, [ 15,16 ] protective coatings, [ 17,18 ] and cation doping. [ 19,20 ] Although the cycling stabilities of these modified Na 0.44 MnO 2 materials show varying degrees of improvement, the high‐rate capability and full‐cell electrochemical performance remain unsatisfactory.…”

The structural origin of enhanced stability of Na3.32Fe2.11Ca0.23(P2O7)2 cathode for Na-ion batteries

“…1a, compared with NFPO, almost all reflections in NFPO-Ca move to a lower angle, suggesting a larger unitcell volume of NFPO-Ca. Rietveld refinement results show that the lattice parameters of the NFPO compound are a = 6.4126 Å, b = 9.3950 Å, c = 10.9809 Å, and V = 569.9982 Å 3 , respectively, which are smaller than those of NFPO-Ca (a = 6.4536 Å, b = 9.4068 Å, c = 11.0184 Å, and V = 575.9994 Å 3 ). The reason can be ascribed to the lattice expansion with the larger Ca 2+ substitution (r Ca 2+ = 1.0 Å > r Fe 2+ = 0.78 Å) [31,32].…”

“…Due to growing energy shortages, the sustainable storage of new energy sources in large electric energy storage systems (EESs) has been a key issue worldwide [1][2][3]. The scale of EES equipped with an energy generator far exceeds that of hybrid electric vehicles (HEV) or electric vehicles (EV).…”

A Stable Biomass‐Derived Hard Carbon Anode for High‐Performance Sodium‐Ion Full Battery

“…Presently, a large variety of cathode materials have been proposed, such as transition metal oxides, polyanionic‐type compounds, Prussian blue analogues, and organic‐based materials. [ 15–22 ] In the case of anode materials, the research also presents the rapid development trend. Carbon‐based material, alloys, transition metal oxides/sulfides and organic compounds have been widely studied as promising anodes for SIBs.…”