In recent years, Prussian blue analogue (PBA) materials have been widely explored and investigated in energy storage/conversion fields. Herein, the structure/property correlations of PBA materials as host frameworks for various charge‐carrier ions (e.g., Na+, K+, Zn2+, Mg2+, Ca2+, and Al3+) is reviewed, and the optimization strategies to achieve advanced performance of PBA electrodes are highlighted. Prospects for further applications of PBA materials in proton, ammonium‐ion, and multivalent‐ion batteries are summarized, with extra attention given to the selection of anode materials and electrolytes for practical implementation. This work provides a comprehensive understanding of PBA materials, and will serve as a guidance for future research and development of PBA electrodes.
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.
Recent years have witnessed a booming interest in grid-scale electrochemical energy storage, where much attention has been paid to the aqueous zinc ion batteries (AZIBs). Among various cathode materials for AZIBs, manganese oxides have risen to prominence due to their high energy density and low cost. However, sluggish reaction kinetics and poor cycling stability dictate against their practical application. Herein, we demonstrate the combined use of defect engineering and interfacial optimization that can simultaneously promote rate capability and cycling stability of MnO2 cathodes. β-MnO2 with abundant oxygen vacancies (VO) and graphene oxide (GO) wrapping is synthesized, in which VO in the bulk accelerate the charge/discharge kinetics while GO on the surfaces inhibits the Mn dissolution. This electrode shows a sustained reversible capacity of ~ 129.6 mAh g−1 even after 2000 cycles at a current rate of 4C, outperforming the state-of-the-art MnO2-based cathodes. The superior performance can be rationalized by the direct interaction between surface VO and the GO coating layer, as well as the regulation of structural evolution of β-MnO2 during cycling. The combinatorial design scheme in this work offers a practical pathway for obtaining high-rate and long-life cathodes for AZIBs.
Lithium–sulfur (Li–S) batteries have been regarded as a promising energy‐storage system owing to their high theoretical energy density of 2600 Wh kg−1 and low cost of raw materials. However, the dendrite issue of Li metal anodes and the shuttle effect of polysulfides severely plague the safety and cycling stability of Li–S batteries. To address these problems, a novel nanoporous battery separator (MMMS) is designed based on an anionic metal–organic framework (MOF) UiO‐66‐SO3Li and poly(vinylidene fluoride) (PVDF) following a mixed‐matrix membrane approach. Benefitting from the well‐defined anionic Li+ transport tunnels across the MMMS, a homogeneous Li deposition is achieved to stabilize the plating/stripping cycling over 1000 h at a high current density of 5 mA cm−2. Moreover, these tunnels featuring anionic electrostatic repulsion and a proper aperture size also demonstrate strong suppression to polysulfide shuttle and promote the redox activity and utilization of sulfur cathode material. With the MMMS to simultaneously promote the performance of Li metal anode and sulfur cathode, the Li–S battery delivers an elevated charge/discharge rate up to 5 C (552 mAh g−1) as well as a low capacity fading (0.056% per cycle at its steady stage) over 500 cycles at 0.5 C.
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