Suppressing O3−O’3 phase transition in NaCrO2 cathode enabling high rate capability for sodium-ion batteries by Sb substitution

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.…”

“…In order to mitigate the above-mentioned issues, several strategies have been employed, including metal-ion doping, surface coating, and multiphase combination. ,− Among them, metal-ion doping is considered the most effective way to suppress structural distortion by controlling the oxidation states of TM. This chemical modification can reduce the Na-ion diffusion energy barrier and suppress phase transitions, enabling a higher rate capability and stability. , Among many dopants investigated, Ma et al recently reported that doping a small amount of Sb ions in the O3-NaCrO 2 cathode can broaden the Na + diffusion channel and suppress the O3 → O′3 phase transition, which is beneficial to electrochemical performance . However, to the best of our knowledge, the effect of Sb doping in O3-type Ni/Mn-based binary oxide cathodes is still poorly understood.…”

Unprecedented Cyclability and Moisture Durability of NaCrO2 Sodium-Ion Battery Cathode via Simultaneous Al Doping and Cr2O3 Coating

“…O3–Na 0.9 Cr 0.9 Sb 0.05 O 2 retained 70.9% of its initial capacity (111 mAh g –1 ) after 1000 C/D cycles compared to 46.8% retention in pristine NaCrO 2 . Surface modification has also been investigated to improve cyclic stability, ,,− in which the surface layer either suppresses side reactions on the cathode surface (e.g., oxidation of chemical species reduced on anodes) or prevents solvent insertion into Na layers. , Carbon was the most popular choice in this category, and various precursors, including citric acid, pitch, coffee waste, and acetylene, have been used for the carbon coating of O3-NaCrO 2 . Among them, pitch-derived carbon-coated O3-NaCrO 2 showed the highest cyclic stability, with approximately 90% of its initial capacity retained after 300 C/D cycles …”

“…To address the stability issue of O3-NaCrO 2 , the control of phase transitions and thus the mitigation of dimensional changes have been investigated through isovalent/aliovalent substitution for Cr 3+ . − For example, Ma et al recently reported that phase transitions can occur through an O3/P3 solid–solution state with no O′3 monoclinic phase by Sb substitutions. O3–Na 0.9 Cr 0.9 Sb 0.05 O 2 retained 70.9% of its initial capacity (111 mAh g –1 ) after 1000 C/D cycles compared to 46.8% retention in pristine NaCrO 2 .…”

“…To address the stability issue of O3-NaCrO 2 , the control of phase transitions and thus the mitigation of dimensional changes have been investigated through isovalent/aliovalent substitution for Cr 3+ . − For example, Ma et al recently reported that phase transitions can occur through an O3/P3 solid–solution state with no O′3 monoclinic phase by Sb substitutions. O3–Na 0.9 Cr 0.9 Sb 0.05 O 2 retained 70.9% of its initial capacity (111 mAh g –1 ) after 1000 C/D cycles compared to 46.8% retention in pristine NaCrO 2 . Surface modification has also been investigated to improve cyclic stability, ,,− in which the surface layer either suppresses side reactions on the cathode surface (e.g., oxidation of chemical species reduced on anodes) or prevents solvent insertion into Na layers. , Carbon was the most popular choice in this category, and various precursors, including citric acid, pitch, coffee waste, and acetylene, have been used for the carbon coating of O3-NaCrO 2 .…”