Metal-organic-framework-derived hollow polyhedrons of prussian blue analogues for high power grid-scale energy storage

Prussian blue and its analogues are recognized as a class of attractive materials for stationary energy storage on the electrical grid. Challenges are still existed to meet the rigid requirements of high power and long cycle life. In this work, we develop a universal metal-organic-framework templating strategy for fabricating hollow polyhedrons of prussian blue analogues with tailored composition and shape. Hollow dodecahedrons of cobalt hexacyanoferrate (CoHCF) are investigated as a proof-of-concept material, which shows high surface area and mesoporous characteristics. The CoHCF hollow dodecahedrons exhibit large Na+ storage capacity in neutral aqueous electrolytes and particularly, superhigh rate capability owing to rapid ion diffusion rate and short carrier transport distances. By coupling with a low-cost carbon anode, hybrid Na-ion cells are constructed to deliver moderate specific energy (32.7-50 Wh kg(-1)), a high specific power of 30 kW kg(-1), and superior 3000-cycling durability. The excellent electrochemical properties make the present aqueous Na-ion hybrid devices to be a promising alternative to lead-acid batteries for high power grid-scale energy storage. (C) 2019 Elsevier Ltd. All rights reserved.