Fluffy-Like Cation-Exchanged Prussian Blue Analogues for Sodium-Ion Battery Cathodes

Abstract

Prussian blue (PB) and its analogues are considered as promising cathode materials for sodium-ion batteries (SIBs) owing to their low cost and high capacity. However, it is still a huge challenge to avoid obvious capacity decay during cycling due to the structural collapse. Herein, we design a method to replace parts of Fe ion sites in PB with Ni ions to prepare fluffy-like nickel PB (PB-Ni) by cationic solution immersion, which improves cycling stability for sodium storage. The content of Ni in PB-Ni is explored by regulating the soaking time in the Ni-containing solution, which results in different effects on the electrochemical performance as cathodes of SIBs. Especially, PB-Ni-1d (soaking in NiCl2 solution for 1 day) exhibits an initial capacity of 114.2 mA h g–1 at 50 mA g–1 and a stable cycling performance of 800 cycles at 300 mA g–1. Furthermore, the reversible phase transformation and small volume variation for PB-Ni-1d are revealed by in situ X-ray diffraction characterization. The nickel hexacyanoferrate in outer layer maintains the cubic phase to stabilize the crystal structure. The cation-exchange strategy provides a facile idea to fabricate high-quality PB cathodes with superior stability for high-performance SIBs.

Unleashing the Potential of Sodium‐Ion Batteries: Current State and Future Directions for Sustainable Energy Storage

“…To overcome this issue, using the cationic solution immersion technique, a part of the Fe site in PB is replaced by Ni to generate a fluffy‐like nickel structure denoted as (PB‐Ni) to enhance the Na‐storage significantly. [ 119 ] The content of Ni can be regulated by controlling the soaking time, which results in varying electrochemical performances. The PB‐Ni exhibited a specific capacity of 114.2 mAh g −1 at 50 mA g −1 and long‐term stability over 800 cycles at 300 mA g −1 .…”

Recent Progress of Promising Cathode Candidates for Sodium‐Ion Batteries: Current Issues, Strategy, Challenge, and Prospects

“…[54] When inactive elements such as Ni, Cu, and Zn are used for doping in PBAs, their main role is to enhance the structural stability rather than directly participate in the redox reactions. [173] For example, Zhou et al [175] substituted a few Fe ions by Ni within a hollow structure PB (PB-Ni). As shown in Figure 13a, after being immersed in NiCl 2 solution for one day, partial Fe ions in hollow structure PB (HS-PB) will be replaced by Ni ions.…”

“…Peng et al [177] introduced the high-entropy (HE) concept into hexacyanoferrate and designed high-entropy metal-organic frameworks (MOFs) containing Na Reproduced with permission. [175] Copyright 2022, America Chemical Society. e-g) In situ, XRD enlarged the 3D colormap surface with projection and 2D contour images of ZnFeHCF-2.…”

Controlled Crystallization of Carbon-blended Prussian Blue Analogs for Advanced Sodium-Ion Batteries

“…Numerous studies of notable value have been undertaken to investigate the potential of PBA electrodes for employment in SIBs. Specifically, PBAs based on Mn/Ni/Co/Cu have been extensively explored, as documented in a plethora of literature sources. − In contrast, low-priced and abundant Fe-based PBAs-A x M­[Fe­(CN) 6 ] y (A = Li, Na, K, etc., M = Fe, Co, Ni, etc., 0 < x < 2, 0 < y < 1) still occupy an important position, relying on the electrochemically active redox sites of Fe, which can contribute high energy density. In the three-dimensional open framework structure, Fe and M atoms are situated on corner-sharing octahedra that are interconnected by linear anionic cyanide ligands placed on alternating corners of the cubes .…”