Informatization, automated modern society continues to advance, and electrochemical energy storage devices play an important role. Beginning in the 1990s, with the commercialization of lithium-ion battery, since the 21 century, lithium-ion batteries have become part of our lives, lithium-ion battery portable devices, electric vehicles have been around in every corner of life. However, the more you sell with other commercial products, the cheaper it is. The scarce lithium resources make the future cost of lithium-ion batteries continue to rise. The search for an alternative low-cost electrochemical energy storage device has become an urgent problem to be solved. The electrochemical properties of potassium and sodium are similar to those of lithium, and the earth's reserves are abundant, which is the best choice for replacing lithium-ion batteries in the future.

The research on sodium ion battery has made great progress in recent years. However, its standard electrode potential (-2.71 V, vs SHE.) and large ionic radius limit make the current energy density and power density of sodium ion battery still and lithium ion. There is a big gap in the battery. The standard electrode potential of potassium (-2.93 V, vs SHE.) is closer to lithium (-3.04 V, vs SHE.), since the ionic radius of potassium and sodium ions is larger than that of lithium ions, although the energy density is less than that of lithium ions. However, the current study of potassium ion negative carbon materials shows that the power density of potassium ion batteries is higher than that of sodium and closer to lithium ion batteries, and the rate performance is better. However, the research on potassium ion cathode materials is very rare at present, most of the research uses aqueous solution as electrolyte, and the voltage window is limited. Recently, the research team of Professor Lei Yong from the Technical University of Ilmnau, Germany, and the research group of Shanghai University have prepared a low-cost dye nanoparticle: Prussian blue, which is used as a potassium ion cathode material in organic The electrochemical properties exhibited in the electrolyte are described in detail. At the same time, it is used as a potassium ion cathode material to match the high-performance potassium ion battery for the first time. The test results show that: Prussian blue as a potassium ion cathode material exhibits a high discharge platform (3.1 – 3.4 V) and a stable reversible specific capacity, which still has 73.8 mAh/g at a charge and discharge rate of 50 mA/g. The cycle specific capacity, and the rate of degradation is very slow, only 0.09 % per-cycle. At the same time, by analyzing the electrochemical storage mechanism of Prussian blue molecules, they found that the framework molecular structure is very beneficial for the storage and release of potassium ions with a large radius. Its main active position is on C-FeII/FeIII. Finally, they used this positive electrode material and combined with super P which has been commercialized as the negative electrode material. The first design matched the potassium ion full battery. The full battery has a reversible specific capacity of 68.5 mAh at a charge and discharge rate of 100 mA/g. /g, and has a long cycle life, which still retains a specific capacity of 93.4% after 50 cycles of charge and discharge cycles. For a larger radius of potassium ions, such a breakthrough is commendable.

The low-cost Prussian blue dye as a potassium ion cathode material and its all-cell matching design have made lithium-ion batteries a better alternative. This research will provide future research and commercial applications of potassium-ion batteries. A broad prospect. This paper has been published online in Advanced Functional Materials (DOI:10.1002/adfm.201604307) and is briefly introduced on the current Back Cover.

Bearing Housing is a most important component of conveyor rollers, and Conveyor Roller is a most important component of belt conveyor.