Since last decade, lithium-ion batteries (LIB) have been intensively employed in applications such as powering of electronic portable devices and electric cars. Nevertheless, concerns regarding limited availability of lithium on the Earth’s crust have led researchers to look for alternative battery chemistries beyond those based on lithium compounds, namely, sodium and potassium ions – monovalent-ions that possess advantages such as low cost due to their abundant availability. Nonetheless, there are challenges associated with the development of sodium and potassium-based batteries due to the lack of suitable electrode materials and limited understanding of charge storage mechanisms in those that must be overcome. Concerning potential electrode materials for non-lithium alkali metal-ion batteries, research efforts have mainly focused on identifying new compositions that offer high electrochemical activity and cycling stability and developing techniques for production in large quantities in a cost-effective manner. In this regard, two-dimensional (2D) materials are desired electrode materials due the existence of inexhaustible active sites, which may lead to higher theoretical capacity. Under the 2D materials umbrella, graphene is the most known species; however, it is a 2D material made from a single element (carbon), whose current functionalization processes may result in the loss of some of graphene unique properties. On the other hand, transition metal dichalcogenides (TMDs) are also layered materials with more 40 species known; thus, yielding in a plethora of chemistries. However, exfoliation of these materials still present issues with respect to scalability, restacking and aggregation of the exfoliated nanosheets, for example. As one of the latest 2D materials discovered, transition metal carbides, carbonitrides and nitrides (MXenes) have been gaining traction. MXenes are layered materials with generalized formula is M~n+1~X~n~T~x~ , where M is a transition metal, X is a carbon and/or a nitrogen atom, and T~x~ a surface termination, for instance, chlorine, fluorine, hydroxyl, or oxygen. As a fast-growing family of 2D materials, since 2011 more than 30 MXene species were reported; therefore, offering a variety of chemistries, electrical and mechanical properties. Here we study two MXene species, namely Mo~2~TiC~2~ and Mo~2~Ti~2~C~3~ as anode materials for sodium (SIB) and potassium-ion batteries (KIB). Results indicate reasonable cycling stability under galvanostatic charge-discharge (GCD) of both MXenes as SIB and KIB, tested at 40 mA g^-1^. In addition, after 50 GCD cycles, KIB cells show higher specific charge capacity than SIB cells, evidence that the charge storage mechanism goes beyond the Na^+^ and K^+^ ion radii. Electrochemical impedance (EIS) studies are also presented, which provide a quantitative analysis of the impedance data to further understand processes taking place on the electrode system. To summarize, this is an initial study towards the understanding of 2D molybdenum-based MXene species (Mo~2~TiC~2~ and Mo~2~Ti~2~C~3~) as SIB and KIB, which comprises data with respect to capacity contribution from MXenes species, chemistry taking place for first and second cycles of GCD, charge storage mechanism, and EIS resistance values on the 50^th^ cycle for sodium- and potassium-ion cells. Results show the stability, low equivalent series resistance, and potential of these Mxenes to be employed as active materials or conducting agents for the future of SIB and KIB.


Mo2TiC2 and Mo2Ti2C3 MXene Nanosheets as Electrode Materials for Sodium and Potassium Ion Batteries

Division / Sponsors: 
Aerospace, Bioengineering, Applied Mechanics, Design Engineering Division, Advanced Energy Systems, Manufacturing Engineering Division, Noise Control and Acoustics, Nondestructive Evaluation, Diagnosis, and Prognosis (NDPD), Nuclear Engineering Division, Process Industries Division, Fluids Engineering, Heat Transfer, Materials, Microelectromechanical Systems, Safety Engineering and Risk Analysis, Computers & Information in Engineering


Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2020/volume/84478

IMECE2020 - Virtual Conference

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.