NASICON-structured Na3MnTi(PO4)2.83F0.5 cathode with high energy density and rate performance for sodium-ion batteries

et al. 2022

Preprint

High-voltage cathodes with high power and stable cyclability are needed for future high-performance sodium-ion batteries. However, the low electronic conductivity and poor capacity retention impede the development of Mn-rich phosphate cathodes. Here, a light-weight F doping strategy is reported to modify high-voltage Na4MnCr(PO4)3 cathodes. The light-weight F dopant could decrease the energy gap to 0.22 eV from 1.52 eV and strengthen the adjacent chemical bonding around Mn as confirmed by density functional theory calculations, which ensure the boosted electronic conductivity and suppress Mn dissolution. The combination of in-situ and ex-situ techniques determine that the F dopant has no influence on the Na+ storage mechanisms. As a result, an outstanding rate performance up to 40 C and an improved cycling stability (1000 cycles at 20 C) are thus achieved (best reported performances until now). This work presents an unusual and widely available light-weight anion doping strategy for high-performance polyanionic cathodes.

Section: Resultssupporting

confidence: 90%

Section: Resultssupporting

confidence: 61%

Fluorine anion modification of high-voltage Mn-rich phosphate cathodes for high-power and long-lasting sodium-ion batteries

et al. 2022

Preprint

“…The sol-gel method, featured with low cost, moderate processing temperature and simplicity, is a facile strategy to prepare versatile gels with various physicochemical properties, [168][169][170] indicating its practical prospects in the CDI community. For example, Ding et al 159 proposed a freestanding Mg 2+ -MXene aerogel via the sol-gel method and subsequent freeze-drying treatment without incorporating any external polymeric binders, serving as the CDI electrodes.…”

Section: Other Methods For the Synthesis Of Freestanding CDI Electrodesmentioning

confidence: 99%

Rational fabrication strategies of freestanding/binder-free electrodes for efficient capacitive deionization

Wang

et al. 2023

Mater. Adv.

“…Benefiting from their open structure and single-phase mechanism, phase transitions and lattice distortion are not the main cause of capacity decay in PACs, such as Na 3 (VOPO 4 ) 2 F and Na 3 MnTi(PO 4 ) 2.83 F 0.5 , and many of them have exhibited much more stable cycling after long-term Na + insertion/extraction. [73,74] Complex phase changes also can be detected in PBAs. Most phase changes of PBAs occur in a relatively low voltage range (<4 V), however, and are highly reversible, except for the volume variation.…”

Section: Irreversible Change To the Structure And Morphologymentioning

confidence: 99%

“…The structural unit (XO m ) n− in PACs can provide powerful support to the crystal structure because the covalent bonds in PACs are stronger than the bonds in the TMOs. [74,136,137] PACs with various crystal structures (phosphates, pyrophosphates, mixed structures, silicates) have been investigated as cathodes for SIBs, and they showed highly stable cycling because of their robust frameworks. [138][139][140] The inherent electrical conductivity of PACs is poor, however, inhibiting their rate performance.…”

Section: Polyanion Compoundsmentioning

confidence: 99%

Long‐Cycle‐Life Cathode Materials for Sodium‐Ion Batteries toward Large‐Scale Energy Storage Systems

Advanced Energy Materials

Gao

Liu

et al. 2023

The development of large-scale energy storage systems (ESSs) aimed at application in renewable electricity sources and in smart grids is expected to address energy shortage and environmental issues. Sodium-ion batteries (SIBs) exhibit remarkable potential for large-scale ESSs because of the high richness and accessibility of sodium reserves. Using low-cost and abundant elements in cathodes with long cycling stability is preferable for lowering expenses on cathodes. Many investigated cathodes for SIBs are dogged by structural and morphology changes, unstable interphases between the cathode and the electrolyte, and air sensitivity, causing unsatisfactory cycling performance. Therefore, understanding the mechanism of capacity degeneration in depth and developing precise solutions are critical for designing low-cost cathodes that are highly stable under cycling. Herein, recent progress in long-cycle-life and low-cost cathodes for SIBs is focused on, and a comprehensive discussion of the key points in SIBs toward large-scale applications is provided. The roots of the unstable cycling performance of low-cost cathodes are discussed. Also, effective strategies are summarized from the recent progress on long-cycle-life and low-cost cathodes. This review is expected to encourage deeper investigation of long-lifespan cathodes for SIBs, particularly for potential large-scale industrialization.