A Dual‐Insertion Type Sodium‐Ion Full Cell Based on High‐Quality Ternary‐Metal Prussian Blue Analogs

Abstract

Prussian blue analogs (PBAs) are especially investigated as superior cathodes for sodium‐ion batteries (SIBs) due to high theoretical capacity (≈170 mA h g−1) with 2‐Na storage and low cost. However, PBAs suffer poor cyclability due to irreversible phase transition in deep charge/discharge states. PBAs also suffer low crystallinity, with considerable [Fe(CN)6] vacancies, and coordinated water in crystal frameworks. Presently, a new chelating agent/surfactant coassisted crystallization method is developed to prepare high‐quality (HQ) ternary‐metal NixCo1−x[Fe(CN)6] PBAs. By introducing inactive metal Ni to suppress capacity fading caused by excessive lattice distortion, these PBAs have tunable limits on depth of charge/discharge. HQ‐NixCo1−x[Fe(CN)6] (x = 0.3) demonstrates the best reversible Na‐storage behavior with a specific capacity of ≈145 mA h g−1 and a remarkably improved cycle performance, with ≈90% capacity retention over 600 cycles at 5 C. Furthermore, a dual‐insertion full cell on the cathode and NaTi2(PO4)3 anode delivers reversible capacity of ≈110 mA h g−1 at a current rate of 1.0 C without capacity fading over 300 cycles, showing promise as a high‐performance SIB for large‐scale energy‐storage systems. The ultrastable cyclability achieved in the lab and explained herein is far beyond that of any previously reported PBA‐based full cells.

The Compensation Effect Mechanism of Fe–Ni Mixed Prussian Blue Analogues in Aqueous Rechargeable Aluminum‐Ion Batteries

“…It is well known that irreversible phase transition owing to deep insertion and extraction of alkaline cations can lead to poor cyclability of PBAs. [17] However,as ignificantly improved cycling performance can be obtained by controlling the charge/discharge depth withoutp hase transition. The calculated D Al 3 + values of the KNHCF electrode in the chargep rocess were in the range 7.2 10 À14 -1.92 10 À12 cm 2 s À1 ,w hereas the values in the discharge process werei nt he range 1.49 10 À13 -6.21 10 À13 cm 2 s À1 .T he D Al 3 + values were higherd uring the chargingp rocess than during the discharging process, which implied faster kinetics of Al 3 + extraction from the open framework than the insertion process.…”

Prussian Blue Analogs as Battery Materials

“…This potential is well within the stability window of water (about À0.18 to 1.05 V versus SHE at pH 3), so they have often been cycled in aqueous electrolyte. The Fe-C bond in the hexacyanoferrates is stable up to at least 200 C 17 and in acid up to pH 2, with solubility increasing with pH as cyanide undergoes ligand exchange with hydroxide groups. 18 This stability makes PBAs attractive as safe battery materials despite the presence of cyanide ligands.…”

Na 3 V 2 (PO 4 ) 3 @NC composite derived from polyaniline as cathode material for high‐rate and ultralong‐life sodium‐ion batteries

“…Similar to LIBs, the performance of SIBs largely depends on the cathode materials. At present, the study on cathode materials of SIBs is mainly concentrated on transition metal oxides, phosphates, pyrophosphate, and Prussian blues . However, the intrinsic properties of these materials, such as serious capacity decay and voltage platform receding because of structural variations during Na + ‐intercalation/removal process or occurring the side reaction, hinder their application in SIBs.…”

“…and Prussian blues. [24][25][26] However, the intrinsic properties of these materials, such as serious capacity decay and voltage platform receding because of structural variations during Na + -intercalation/removal process or occurring the side reaction, hinder their application in SIBs. Compared with them, Na 3 V 2 (PO 4 ) 3 (NVP) with NASICON structure and higher theoretical specific capacity is considered as an ideal cathode material for SIBs.…”