Polyvinylpyrrolidone-Bridged Prussian Blue/rGO Composite as a High-Performance Cathode for K-Ion Batteries

Thin films based on nanocomposites of crumpled graphene fully decorated with Prussian blue: a new material for aqueous battery systems

This study involves synthesizing thin films through an interfacial method, which relies on composites of Prussian blue nanoparticles and nanostructures derived from graphene, known as crumpled graphene. The resulting compounds were subjected to evaluation for potential applications in aqueous battery-type energy storage systems. Considering the importance of structure-property relationships and applications, the carbon nanostructures were previously processed to assess their morphological characteristics and electrochemical performance for the growth of Prussian blue nanocubes. To this end, the spray-pyrolysis method was employed, resulting in crumpled graphene infused with β-FeOOH and Fe2O3 (β-iron(III) oxyhydroxide and iron (III) oxide) species. Composites of crumpled graphene and Prussian blue were synthesized through the electrodeposition method via cyclic voltammetry, which formed Prussian blue nanocubes on the surface of crumpled graphene with sizes ranging from 48 to 153 nm depending on the number of cycles. Specific capacity values varied based on the compound structure, with the highest recorded value of 50.4 mA h g-1 at a rate of 500 mA g-1 for the PB_10 composite achieved in an aqueous electrolyte of 0.1 mol L-1 KCl vs. Ag|AgCl (3.0 mol L-1 KCl). The PB_10 electrode was further studied using different electrochemical techniques and employed in a coin cell battery system, demonstrating a discharge capacity of 25.0 mA h g-1 at 250 mA g-1. Additionally, the device retained 97% of its capacity after cycling at various current densities, highlighting its stability.

Recent advances in rational design for high-performance potassium-ion batteries

The growing global energy demand necessitates the development of renewable energy solutions to mitigate greenhouse gas emissions and air pollution. To efficiently utilize renewable yet intermittent energy sources such as solar and wind power, there is a critical need for large-scale energy storage systems (EES) with high electrochemical performance. While lithium-ion batteries (LIBs) have been successfully used for EES, the surging demand and price, coupled with limited supply of crucial metals like lithium and cobalt, raised concerns about future sustainability. In this context, potassium-ion batteries (PIBs) have emerged as promising alternatives to commercial LIBs. Leveraging the low cost of potassium resources, abundant natural reserves, and the similar chemical properties of lithium and potassium, PIBs exhibit excellent potassium ion transport kinetics in electrolytes. This review starts from the fundamental principles and structural regulation of PIBs, offering a comprehensive overview of their current research status. It covers cathode materials, anode materials, electrolytes, binders, and separators, combining insights from full battery performance, degradation mechanisms, in situ/ex situ characterization, and theoretical calculations. We anticipate that this review will inspire greater interest in the development of high-efficiency PIBs and pave the way for their future commercial applications.

Control of Gradient Concentration Prussian White Cathodes for High-Performance Potassium-Ion Batteries

Owing to their abundant resources and low cost, potassium-ion batteries (PIBs) have become a promising alternative to lithium-ion batteries (LIBs). However, the larger ionic radius and higher mass of K+ propose a challenging issue for finding suitable cathode materials. Prussian whites (PWs) have a rigid open framework and affordable synthesis method, but they suffer quick capacity fade due to lattice volume change and structural instability during K+ insertion/extraction. Here, we prepared controllable gradient concentration KxFeaNibMn1-a-b[Fe(CN)6]y·zH2O particles via a facile coprecipitation process, demonstrating high-performance potassium-ion storage. The high-Mn content in the interior can minimize capacity loss caused by electrochemically inert Ni and achieve a high reversible capacity; meanwhile, the high-FeNi content in the exterior can alleviate the volume change of the core material upon cycling, thus enhancing structural stability. Taking the above synergistic effect, the controllable gradient concentration PWs deliver a high reversible capacity of 109.8 mAh g-1 at 100 mA g-1 and good capacity retention of 77.8% after 200 cycles. The gradient concentration PWs can retain structural integrity and stability during long-term cycling. This work provides a prospective strategy to fabricate PWs with stable structure and excellent electrochemical performance for developing high-performance PIBs.

Enhanced water-resistant performance of Cu-BTC through polyvinylpyrrolidone protection and its capture ability evaluation of methylene blue

Water instability issues greatly restrict the application of Cu-BTC for cationic dye (e.g. methylene blue (MB)) capture from wastewater.