A Reversible Solid-State Crystalline Transformation in a Metal Phosphide Induced by Redox Chemistry

Abstract

We demonstrate low-potential intercalation of lithium in a solid-state metal phosphide. A topotactic first-order transition between different but related crystal structures at room temperature takes place by an electrochemical redox process: MnP4 <--> Li7MnP4. The P-P bonds in the MnP4 structure are cleaved at the time of Li insertion (reduction) to produce crystalline Li7MnP4 and are reformed after reoxidation to MnP4, thereby acting as an electron storage reservoir. This is an unusual example of facile covalent bond breaking within the crystalline solid state that can be reversed by the input of electrochemical energy.

Diagnosis of Electrochemical Impedance Spectroscopy in Lithium-Ion Batteries

“…MO x +2xLi→M 0 +xLi 2 O, which is different from the intercalation/deintercalation mechanism. Later, reversible lithium storage was also observed in transition metal fluorides as well as sulfides, nitrides, selenides and phosphides [7,8,26,63,81,82,89,94,116]. As opposed to intercalation reactions, the reversible conversion process enables the full redox utilization of the transition metal and has 2-4 times the specific capacity of intercalation compounds as high as 600-1000 mAh.g -1 [54].…”

Topotactically synthesized ultralong LiV3O8 nanowire cathode materials for high-rate and long-life rechargeable lithium batteries

“…52 However, the uniform nanowire morphology of V 2 O 5 was destroyed because there was a significant crystal structure change between the precursor V 2 O 5 and the resultant LiV 3 O 8 . The concept of a topotactic intercalation mechanism was suggested to describe the formation of the Li 7 MnP 4 phase from the MnP 4 phase through the insertion of Li ions, 53 which means that there are definite crystallographic relationships between the reactant and the product. Thus, we can obtain a product with a minimal change in structure and morphology from the reactant.…”

Correlating Preparative Approaches with Electrochemical Performance of Fe3O4-MWNT Composites Used as Anodes in Li-Ion Batteries

“…Today LIBs are widely used and denote the battery of choice for a wide range of applications spanning from portable electronics to electric vehicles. [1][2][3][4][5] Although LIBs have shown impressive commercial success, an understanding of the intrinsic functioning of LIB electrodes and of their constituent component materials still represents a subject of significant research. In recent years, the use of energy storage devices has expanded into new areas, including with uninterrupted power sources (UPS), stationary storage batteries (SSBs), and the automotive market, the latter of which encompasses both electric vehicles and hybrid electric vehicles.…”