Engineering of high-performance potassium-ion capacitors using polyaniline-derived N-doped carbon nanotubes anode and laser scribed graphene oxide cathode

Potassium (K) ion storage technology is recently receiving a great attention due to their low-cost and enormous abundance on the earth compared to lithium. However, the technology is still at a scientific research stage and exploring suitable electrode materials is a key challenge. Herein, we have engineered nitrogen doped carbon nanotubes (N-CNTs) as a promising anode material for K-ion storage through pyrolytic decomposition of polyaniline nanotubes (PAni-NTs). These N-CNTs delivers high reversible capacity with good rate performance and cycling stability. Taking advantage of these features, a potassium-ion hybrid capacitor (KIHC) is constructed using N-CNTs as battery-type anode and 3-dimensional (3D) laser scribed graphene (LSG) as capacitor-type cathode electrodes. The device displays a high energy density of 65 W h/kg, a high power output of 1000 W/kg, as well as a long cycling life (91% capacity retention over 5000 cycles). Thus, such an advanced energy storage system can satisfy the requirements of high power and high energy densities simultaneously in diverse applications at low-cost.Mahmoud Moussa, Sameer A. Al-Bataineh, Dusan Losic, Deepak P. Duba

Graphene and molybdenum disulphide hybrids for energy applications: an update

Graphene and its analog, two-dimensional (2D) layered molybdenum disulphide (MoS2), have been used for 'clean energy' applications in the last several years because of their remarkable electrochemical, optical, and magnetic properties. Their huge success and application potential in various fields has led to the investigation of new 2D nanomaterials which cross the boundaries of existing graphene-based devices. The combination of chemically inert graphene and redox-active MoS2 in a single electrode is providing new opportunities to improve the performance of energy devices and circumvent existing limitations. This article updates our previous review on advances in graphene-MoS2 hybrids for energy-oriented applications. In particular, a summary of recent developments in the synthesis of the graphene-MoS2 hybrids, with an emphasis on energy storage and hydrogen production, is provided. Future challenges and opportunities associated with the development of 2D hybrid materials, and their applications in energy storage systems, are discussed. (C) 2019 The Authors. Published by Elsevier Ltd

Recycle, recover and repurpose strategy of spent Li-ion batteries and catalysts: current status and future opportunities

The disposal of hazardous waste of any form has become a great concern for the industrial sector due to increased environmental awareness. The increase in usage of hydroprocessing catalysts by petrochemical industries and lithium-ion batteries (LIBs) in portable electronics and electric vehicles will soon generate a large amount of scrap and create significant environmental problems. Like general electronic wastes, spent catalysts and LIBs are currently discarded in municipal solid waste and disposed of in landfills in the absence of policy and feasible technology to drive alternatives. Such inactive catalyst materials and spent LIBs not only contain not only hazardous heavy metals but also toxic and carcinogenic chemicals. Besides polluting the environment, these systems (spent catalysts and LIBs) contain valuable metals such as Ni, Mo, Co, Li, Mn, Rh, Pt, and Pd. Therefore, the extraction and recovery of these valuable metals has significant importance. In this Review, we have summarized the strategies used to recover valuable (expensive) as well as cheap metals from secondary resources-especially spent catalysts and LIBs. The first section contains the background and sources of LIBs and catalyst scraps with their current recycling status, followed by a brief explanation of metal recovery methods such as pyrometallurgy, hydrometallurgy, and biometallurgy. The recent advances achieved in these methods are critically summarized. Thus, the Review provides a guide for the selection of adequate methods for metal recovery and future opportunities for the repurposing of recovered materials.Dipak J. Garole, Rumana Hossain, Vaman J. Garole, Veena Sahajwalla, Jawahar Nerkar, and Deepak P. Duba

Large interspaced layered potassium niobate nanosheet arrays as an ultrastable anode for potassium ion capacitor

Available online 16 October 2020Potassium-ion battery (KIB) is a promising technology for large-scale energy storage applications due to their low cost, theoretically high energy density and abundant resources. However, the development of KIBs is hin- dered by the sluggish K + transport kinetics and the structural instability of the electrode materials during K + intercalation/de-intercalation. In the present investigation, we have designed a potassium-ion capacitor (KIC) using layered potassium niobate (K 4 Nb 6 O 17 , KNO) nanosheet arrays as anode and orange-peel derived activated carbons (OPAC) as fast capacitive cathode materials. The systematic electrochemical analysis with the ex-situ characterizations demonstrates that KNO-anode exhibits highly stable layered structure with excellent reversibil- ity during K + insertion/de-insertion. After optimization, the fabricated KNO//OPAC delivers both a high energy density of 116 Wh/kg and high power density of 10,808 W/kg, which is significantly higher than other similar hybrid devices. The cell also displays long term cycling stability over 5000 cycles, with 87 % of capacity reten- tion. This study highlights the utilization of layered nanosheet arrays of niobates to achieve superior K ‐storage for KICs, paving the way towards the development of high ‐performance anodes for post lithium ‐ion batteries.Hong Duc Pham, Nilesh R. Chodankar, Sagar D. Jadhav, Kolleboyina Jayaramulu, Ashok Kumar Nanjundan, Deepak P. Duba

Enriched pseudocapacitive lithium storage in electrochemically activated carbonaceous vanadium(iv,v) oxide hydrate

Hydrated vanadium oxides (HVOs) are promising (extrinsic) pseudocapacitive materials that extend the possibility to optimize electrochemical performance through fine-tuning their nanoscale porosity, structural disorder and conventional composition. These materials demonstrate the features of batteries (i.e. high energy density) and supercapacitors (fast power output). However, most pseudocapacitive oxides are characterized by poor conductivity, which leads to high electrode resistance. Herein, an amorphous-like carbon-integrated vanadium oxide hydrate (V5O12·0.4H2O, CHVO) is engineered using a straightforward solvothermal approach, with improved conductivity, rich pore architecture and readily available nanoscale redox-active sites. The CHVO material shows superior performance as an anode in Li-ion batteries with a specific capacity of 1175 mA h g−1 at 50 mA g−1 in the 150th cycle, which was maintained to 525 mA h g−1 over 600 cycles at 1000 mA g−1. The half-cell can be charged to 403 mA h g−1 (1451 C g−1) at 4000 mA g−1 in ∼6 min. The cyclic voltammetry analysis shows that CHVO undergoes an electrochemical activation by forming a stable lithium vanadium oxide in the initial cycles. The research on electrochemical de(lithiation) mechanism of HVOs at low potentials (<1 V) is largely unexplored. In this context, real time measurements using in situ Transmission Electron Microscopy are provided to underpin the Li-ion transport process in CHVO electrodes. It is revealed that the carbon framework and peculiar structure of CHVO effectively buffer large volume expansions upon (de)lithiation. In addition, ex situ X-ray photoelectron spectroscopy and X-ray Diffraction measurements were collectively utilized to uncover a conversion-type reaction mechanism.Joseph F. S. Fernando, Dumindu P. Siriwardena, Konstantin L. Firestein, Chao Zhang, Joel E. von Treifeldt, Deepak P. Dubal ... et al

Spent graphite from end-of-life Li-ion batteries as a potential electrode for aluminium ion battery

Graphite is central in almost all commercial Li-ion batteries (LIBs) and possesses attractive physical and chemical properties such as good ionic conductivity and layered graphitic structure. In this communication, we have demonstrated the recycling of graphite from end-of-life LIBs and the re-purposing of the recovered material for positive electrodes in next-generation aluminium-ion-batteries (AIBs). The recovered graphite possesses enlarged interlayer spacing which is shown to effectively boost Al-ion insertion/de-insertion during the charge/discharge processes. Excellent Al-ion storage performance is achieved with the capacity reaching 124 mAh g⁻¹ at 50 mA g⁻¹. The material retained a capacity of 55 mAh g⁻¹ even after the applied current was increased to 500 mA g⁻¹, showing its capability to deliver high rate performance. The charge/discharge cycling further revealed that the graphite retains 81% of its initial capacity even after 6700 cycles at a high rate of 300 mA g⁻¹. This excellent aluminium ion storage performance makes the recovered graphite a promising positive electrode material, providing a possible solution for the recycling of huge amounts of LIB scrap. At the same time, this material aids the development of alternative sustainable battery technology, as an alternative to LIBs.Hong Duc Pham, Michael Horn, Joseph F.S. Fernando, Rohan Patil, Manisha Phadatare, Dmitri Golberg, Håkan Olin, Deepak P. Duba

True meaning of pseudocapacitors and their performance metrics: asymmetric versus hybrid supercapacitors

First published: 06 August 2020The development of pseudocapacitive materials for energy-oriented applications has stimulated considerable interest in recent years due to their high energy-storing capacity with high power outputs. Nevertheless, the utilization of nanosized active materials in batteries leads to fast redox kinetics due to the improved surface area and short diffusion pathways, which shifts their electrochemical signatures from battery-like to the pseudocapacitive-like behavior. As a result, it becomes challenging to distinguish "pseudocapacitive" and "battery" materials. Such misconceptions have further impacted on the final device configurations. This Review is an earnest effort to clarify the confusion between the battery and pseudocapacitive materials by providing their true meanings and correct performance metrics. A method to distinguish battery-type and pseudocapacitive materials using the electrochemical signatures and quantitative kinetics analysis is outlined. Taking solid-state supercapacitors (SSCs, only polymer gel electrolytes) as an example, the distinction between asymmetric and hybrid supercapacitors is discussed. The state-of-the-art progress in the engineering of active materials is summarized, which will guide for the development of real-pseudocapacitive energy storage systems.Nilesh R. Chodankar, Hong Duc Pham, Ashok Kumar Nanjundan, Joseph F. S. Fernando, Kolleboyina Jayaramulu ... Deepak P. Dubal ... et al