Graphene-Roll-Wrapped Prussian Blue Nanospheres as a High-Performance Binder-Free Cathode for Sodium-Ion Batteries

Abstract

Sodium iron hexacyanoferrate (Fe-HCF) has been proposed as a promising cathode material for sodium-ion batteries (SIBs) because of its desirable advantages, including high theoretical capacity (∼170 mAh g), eco-friendliness, and low cost of worldwide rich sodium and iron resources. Nonetheless, its application faces a number of obstacles due to poor electronic conductivity and structural instability. In this work, Fe-HCF nanospheres (NSs) were first synthesized and fabricated by an in situ graphene rolls (GRs) wrapping method, forming a 1D tubular hierarchical structure of Fe-HCF NSs@GRs. GRs not only provide fast electronic conduction path for Fe-HCF NSs but also effectively prevent organic electrolyte from reaching active materials and inhibit the occurrence of side reactions. The Fe-HCF NSs@GRs composite has been used as a binder-free cathode with a capacity of ∼110 mAh g at a current density of 150 mA g (∼1C), the capacity retention of ∼90% after 500 cycles. Moreover, the Fe-HCF NSs@GRs cathode displays a super high rate capability with ∼95 mAh g at 1500 mA g (∼10C). The results suggest that the 1D tubular structure of 2D GRs-wrapped Fe-HCF NSs is promising as a high-performance cathode for SIBs.

Chemical Properties, Structural Properties, and Energy Storage Applications of Prussian Blue Analogues

“…Finally, porous PB spheres were obtained when 3 mL HCl is added into the system (Figure f,i). Based on the hydrothermal method, a variety of PB‐carbon composites have been synthesized, including PB–reduced graphene oxide composite (PB/rGO), PB–carbon nanotube (PB/CNT) composite, and PB–polypyrrole [PB/PPy]) composite . Na x Fe[Fe(CN) 6 ]–graphene and PB/PPy composites are prepared by a two‐step method where PB particles are first synthesized by the hydrothermal method, and then rGO or PPy are coated on the surfaces of the PB particles ( Figure a–d) .…”

“…Owing to its open framework, the alkaline ions can be extracted/intercalated reversibly from/into the PBAs, making them suitable as cathode materials for alkaline ion batteries (Li + , Na + , K + , etc.) and as electrodes for supercapacitors with organic or aqueous electrolytes . Some defects and crystal water inevitably remain in PBAs due to their preparation in aqueous solution, meaning that they can be used as the host for hydrogen storage .…”

Multiscale Graphene‐Based Materials for Applications in Sodium Ion Batteries

“…These can be solved by constructing graphene‐based PBA composite. Luo et al wrapped sodium iron hexacyanoferrate (Fe‐HCF) nanospheres into graphene rolls (GRs) to form 1D tubular hierarchical structure of GR/Fe‐HCF . The GRs endowed the Fe‐HCF nanospheres with enhanced electronic conductivity and meanwhile avoided the contact between electrolyte and active Fe‐HCF nanospheres, leading to the improvement of electrochemical performance.…”

Recent Progress in Iron‐Based Electrode Materials for Grid‐Scale Sodium‐Ion Batteries

“…Na x MFe(CN) 6 , Prussian blue and its analogues are expected to show a larger sodium storage capacity due to the potential two‐electron redox reaction of M and Fe for Na x MFe(CN) 6 . Phase purity, crystallinity, defects, water content, and carbon decoration all have great influence on the electrochemical performance of Prussian blue‐type electrodes . Yang and co‐workers reported single‐crystal FeFe(CN) 6 nanoparticles through a solution precipitation method; the high purity of the FeFe(CN) 6 electrode generates a high reversible capacity of 120 mAh g −1 with long cycle life over 500 cycles .…”