Intercalation of the layer type transition metal dichalcogenides by a variety of organic molecules, alkali metals, or ‘3d’ transition metals, provides a powerful way to finely tune the electron occupation of the relatively narrow ‘d’ bands met in these solids These transition metal dichalcogenides are highly anisotropic solids, sometimes referred to as ‘two-dimensional’ solids, and the intercalant molecules which are electron donors enter between the layers This can result in profound changes in the electronic properties of the host lattice, and these changes can be understood in terms of charge transfer and increased interlayer separation The phenomena discussed include optical properties, transport properties, super-conductivity, order-disorder phenomena and phase changes, staging, magnetic properties, metal-insulator transitions, Anderson localization, and fast-ion conduction Some possible practical applications are also considered

Electronic properties of intercalation complexes of the transition metal dichalcogenides

Reversibly intercalating ions into host materials for electrochemical energy storage is the essence of the working principle of rocking-chair type batteries. The most relevant example is the graphite anode for rechargeable Li-ion batteries which has been commercialized in 1991 and still represents the benchmark anode in Li-ion batteries 30 years later. Learning from past lessons on alkali metal intercalation in graphite, recent breakthroughs in sodium and potassium intercalation in graphite have been demonstrated for Na-ion batteries and K-ion batteries. Interestingly, some significant differences proved to exist for the intercalation of Na+ and K+ into graphite compared with the Li+ case. Such different host-guest interactions are unique depending on the host materials and electrolytes, which greatly contribute to a deeper understanding of intercalation-type electrode materials for next generation alkali metal ion batteries. This review summarizes significant advances from both experimental and theoretical calculations with a focus on comparing the intercalation of three alkali metal ions (Li+, Na+, K+) into graphite and aims to clarify the intimate host-guest relationships and the underlying mechanisms. New approaches developed to achieve favorable intercalation coupled with the challenges in this field are also discussed. We also extrapolate alkali metal ion intercalation in graphite to mono-/multi-valent ions in layered electrode materials, which will deepen the understanding of intercalation chemistry and provide guidance to explore new guests and hosts.

Intercalation chemistry of graphite: alkali metal ions and beyond.

Revitalized interest in vanadium pentoxide as cathode material for lithium-ion batteries and beyond

Substituted polyaniline/chitosan composites : Synthesis and characterization

Cellulose/graphite oxide composite films with improved mechanical properties over a wide range of temperature

Elastic energy and staging in intercalation compounds

Phase mixtures and staging in intercalated LixNbSe2

A sensor has been developed to monitor objects passing through tunnels using a capacitance bridge. While the sensor concept is easily adaptable to a wide range of objects or organisms which pass through an enclosed area, our version of the sensor was designed specifically for monitoring bumblebee colonies. Other bee sensors have been developed based on optical methods of detection. The capacitance sensor provides all the information of the optical sensors and additional information on the bee size and velocity. The sensor is expected to provide entomologists with more efficient methods of studying the foraging activities of bees.

https://iopscience.iop.org/article/10.1088/0957-0233/16/12/015/pdf

Douglas C. Dahn

Papers

Elastic energy and staging in intercalation compounds

Phase mixtures and staging in intercalated LixNbSe2

Capacitance-based sensor for monitoring bees passing through a tunnel

In situ polymerization/intercalation of substituted anilines into iron (III) oxychloride

Electrical characterization of conductive polymers and their intercalated nanocomposites with molybdenum disulfide