No abstract

This work provides an alternative solution to the challenge of battery recycling via the upcycling of spent lithium cobalt oxide (LCO) as a new promising solid lubricant additive. An advanced solid lubricant mixture of graphene, Aremco binder, and recycled LCO was formulated into a spray with the use of excess volatile organic solvent. Numerous flat steel disks were spray-coated with the new lubricant formulation and naturally dried followed by curing at 180 °C. When tested on a ball-on-disk up to 230 m in distance, the composite new solid lubricant reduced the coefficient of friction (COF) by 85% between two steel surfaces compared to unlubricated surfaces under a constant 1 GPa Hertzian pressure in an ambient environment. The tribofilm composition, particle size, and type of contact are identified as important parameters in the improvement of the COF. Scanning electron microscopy was used to study its morphology, and energy dispersive X-ray spectroscopy was used to analyze the composition of pristine and tested tribofilms. Upcycled spent low value LCO powder was used as a lubricant additive in tribology for the first time with exceptional lubricious properties.

The development of realistic lithium metal batteries (LMBs) is highly desirable to address the steady increase in the energy‐storage demand for high‐power applications. Consequently, the polydopamine‐tailored polypropylene separator enables scale up with ≈8 μm‐thick graphene nanosheets coating on the polypropylene separator. A layered LiNi1/3Mn1/3Co1/3O2 (LNMC) cathode is characterized by X‐ray diffraction analysis (XRD) and scanning electron microscopy (SEM) analysis, which exhibits single phase purity with a hexagonal structure, R3¯m space group, and a homogenized spherical shape morphology with secondary particles comprising primary particles. Lithium metal battery pouch cells (LMBPCs) are fabricated based on the proposed design strategies, containing a lithium metal anode, LNMC cathode, and tailored polypropylene separator without any internal short circuit, wherein polydopamine and graphene nanosheets layers are positioned toward the LNMC cathode in the pouch cell stacking order. The assembled pouch cell is cycled between 3.0 and 4.2 V and delivers a cell capacity of ≈500 mAh. Then the charged LMBPCs are connected to the prototype electronic truck and demonstrated on various surfaces at 25 °C and < −5 °C. From the prototype truck demonstration results, LMBPCs are useful for practical high‐power applications, including electric vehicles, hybrid electric vehicles, and grid energy storage.

Researchers frequently come across catalyst performance reported as either conversion or rate of reaction as a function of time on stream. When different publications reported data in different manners, comparison of the performance of even similar catalysts becomes difficult. The same situation arises when catalytic behavior is shown at different space velocities. This is because catalyst deactivation characteristics depend on space velocity in addition to rate constants for the main chemical reaction as well as the deactivation process. To circumvent this difficulty, we have furthered the concept of conversion capacity originally brought out by Janssens (J. Catal., 2009;264:130–137) for methanol/dimethyl ether conversions. Conversion capacity was defined by him as the maximum amount of the reactant converted by the time the catalyst affords zero conversion. He developed equations for the first‐order main‐ and deactivation‐ reaction. However, many reactions of practical importance are of order two. We have developed expressions for the second‐order reactions to determine conversion capacity and also the time required for reaching 50% of the initial conversion, t0.5 for the reaction occurring in a plug flow reactor. Here we have given the example calculations for conversion capacity for the reaction of methane tri‐reforming taking data from two different published articles reporting conversion and rate of reaction as a function of time‐on‐stream. We further show the usefulness of these two parameters as giving information not only on the life of the catalysts but also their relative catalytic performance by drawing parallels between reported information and values determined here. Still, a word of caution is necessary. Expression for rate versus time on stream is valid for a linear relationship. Also, values of conversion capacity and t0.5 obtained by expressions given here are qualitative in nature and should be used for comparison purposes rather than attaching any physical significance to them.

Tailored separator consisting of graphene–polydopamine coatings on polypropylene to enhance the performance of Li–S batteries by tackling sulfur conductivity, polysulfide shuttling, and lithium dentritic growth issues.