Prussian blue positive pole material and preparation method thereof, and electrochemical energy storage device

Abstract

The invention provides a prussian blue positive pole material and a preparation method thereof, and an electrochemical energy storage device. The molecular formula of the positive pole material is AxMc[M'(CN)6]y, wherein the A is one or more of H<+>, Li<+>, Na<+>, K<+> and NH4<+>, the M is transition metal, and M' is also the transition metal, 0 < x <= 2, 0 < y < 1, and 0 < c <= 1. The positive pole material has a porous structure and a high specific surface area, so that the diffusion and transmission path of ions and electrons can be obviously shortened, both the ion and electron conductiveproperties of the electrochemical energy storage device can be enhanced, and therefore, the cycle performance and rate performance of the electrochemical energy storage device can be improved; and thecontact with a conductive agent can be also increased, the electron conductive properties of the electrochemical energy storage device can be further enhanced, and the cycle performance and rate performance can be further improved as well.

Description

technical field [0001] The present application relates to the field of energy storage devices, in particular to a Prussian blue positive electrode material, a preparation method thereof, and an electrochemical energy storage device. Background technique [0002] In recent years, with the rapid development of energy storage technology, sodium-ion batteries have become a hot spot in the research of electrochemical energy storage technology because of their rich resources, environmental friendliness and low cost; and their cathode materials are one of the key factors restricting the application of sodium-ion batteries . Prussian blue and its derivatives have a suitable open frame structure, which can be Na + It provides fast-transporting ion channels and is an excellent cathode material for sodium-ion batteries. [0003] However, the solubility of Prussian blue and its derivatives in aqueous solution is extremely low, and the reaction speed of metal cyanide and free metal cat...

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Problems solved by technology

[0003] However, the solubility of Prussian blue and its derivatives in aqueous solution is extremely low, and the reaction speed of metal cyanide and free metal cations in the liquid phase is extremely fast. It is difficult to control the nucleation and crystal growth rate during the preparation process, resulting in the co-precipitation of Prussian blue. The particle sizes of blue and its derivatives are different, and the interparticle agglomeration is serious. At the same time, there are many defects in the product, such as holes, interstitial water and complex water.

The inhomogeneity of the physical and chemical properties of Prussian blue and its derivatives will cause the collapse of the skeleton structure storing sodium ions during the electrochemical cycle, resulting in low Coulombic efficiency of sodium-ion batteries and rapid charge-discharge capacity decay. There may even be a capacity "diving" phenomenon

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