High Performance Lithium-Ion Batteries Using Layered 2H-MoTe2 as Anode.

The major challenges faced by candidate electrode materials in lithium-ion batteries (LIBs) include their low electronic and ionic conductivities. 2D van der Waals materials with good electronic conductivity and weak interlayer interaction have been intensively studied in the electrochemical processes involving ion migrations. In particular, molybdenum ditelluride (MoTe2 ) has emerged as a new material for energy storage applications. Though 2H-MoTe2 with hexagonal semiconducting phase is expected to facilitate more efficient ion insertion/deinsertion than the monoclinic semi-metallic phase, its application as an anode in LIB has been elusive. Here, 2H-MoTe2 , prepared by a solid-state synthesis route, has been employed as an efficient anode with remarkable Li+ storage capacity. The as-prepared 2H-MoTe2 electrodes exhibit an initial specific capacity of 432 mAh g-1 and retain a high reversible specific capacity of 291 mAh g-1 after 260 cycles at 1.0 A g-1 . Further, a full-cell prototype is demonstrated by using 2H-MoTe2 anode with lithium cobalt oxide cathode, showing a high energy density of 454 Wh kg-1 (based on the MoTe2 mass) and capacity retention of 80% over 100 cycles. Synchrotron-based in situ X-ray absorption near-edge structures have revealed the unique lithium reaction pathway and storage mechanism, which is supported by density functional theory based calculations.

Highly Efficient Recovery and Recycling of Cobalt from Spent Lithium-Ion Batteries Using an N-Methylurea-Acetamide Nonionic Deep Eutectic Solvent.

The growing demand for lithium-ion batteries (LiBs) for the electronic and automobile industries combined with the limited availability of key metal components, in particular cobalt, drives the need for efficient methods for the recovery and recycling of these materials from battery waste. Herein, we introduce a novel and efficient approach for the extraction of cobalt, and other metal components, from spent LiBs using a nonionic deep eutectic solvent (ni-DES) comprised of N-methylurea and acetamide under relatively mild conditions. Cobalt could be recovered from lithium cobalt oxide-based LiBs with an extraction efficiency of >97% and used to fabricate new batteries. The N-methylurea was found to act as both a solvent component and a reagent, the mechanism of which was elucidated.

Electrocatalytic Activity of Polyaniline in Magnesium-Sulfur Batteries.

Rechargeable magnesium-sulfur (Mg-S) batteries offer the potential for inexpensive energy storage alternatives to other metal-ion batteries for the grid scale and household applications. Despite all economic and resource advantages, Mg-S battery chemistry suffers from a complicated reaction mechanism and extremely slow reaction kinetics. To improve the kinetics, we improvise a new electrode architecture where a conductive polymer is used along with a carbon network. This report will bring an important insight of electrocatalytic activity of polyaniline, on the basis of free-radical coupling and is a completely new concept in Mg-S battery chemistry. By the combined electron spin resonance spectroscopy, X-ray photoelectron spectroscopy, and fluorescence lifetime measurements, we perceived that the polyaniline anchors the S3•- species from the electrolyte/catholyte through a free-radical-coupling process and thus promotes the reduction to end-discharged products, via a chemical adduct. The concept of free-radical catalysis in Mg/S batteries will open a new knowledge to enhance the active material utilization in the Mg-S batteries.