Catalyst For Lithium-oxygen Batteries Research Articles

Tailoring the Growth and Morphology of Lithium Peroxide: Nickel Sulfide/Nickel Phosphate Nanotubes with Optimized Electronic Structure for Lithium-Oxygen Batteries.

Heterogeneous crystalline-amorphous structures, with tunable electronic structures and morphology, hold immense promise as catalysts for lithium-oxygen batteries (LOBs). Herein, a nanotube network constructed by crystalline nickel sulfide/amorphous nickel phosphate (NiS/NiPO) heterostructure is prepared on Ni foam through the sulfurization of the precursor generated hydrothermally. Used as cathodes, the NiS/NiPO nanotubes with optimized electronic structure can induce the deposition of the highly porous and interconnected structure of Li2 O2 with rich Li2 O2 -electrolyte interfaces. Abundant active sites can be created on NiS/NiPO through the charge redistribution for the uniform nucleation and growth of Li2 O2 . Moreover, nanotube networks endow cathodes with efficient transport channels and sufficient space for the accommodation of Li2 O2 . A high discharge capacity of 27 003.6 mAh g-1 and a low charge overpotential of 0.58V at 1000 mAh g-1 can be achieved at 200mA g-1 . This work provides valuable insight into the unique role of the electronic structure and morphology of catalysts in the formation mechanisms of Li2 O2 and the performances of LOBs.

Facile Fabrication of Ag Nanocrystals Encapsulated in Nitrogen‐doped Fibrous Carbon as an Efficient Catalyst for Lithium Oxygen Batteries

A facile synthesis of Ag nanocrystals encapsulated in nitrogen‐doped carbon fiber (NCF) is proposed, based on the simultaneous reaction between pyrrole and Ag+ ions in an aqueous solvent followed by a heat treatment. The as‐prepared Ag/NCF demonstrated superior catalytic behavior toward ORR and OER. Besides improved cycling stability, a much lower discharge/charge gap of 0.89 V (vs Li/Li+) compared with 1.38 V for NCF cathode with a fixed capacity of 500 mAh g−1 was obtained in lithium oxygen batteries. The introduction of Ag crystals into NCF facilitates the oxygen reduction reaction/oxygen evolution reaction kinetics. X‐ray diffraction analysis coupled with Raman spectroscopy confirmed that Ag/NCF cathode could reversibly catalyze Li2O2 formation and decomposition. The NCF matrix offers a conductive network to realize rapid mass transfer and the encapsulated Ag nanocrystals supplied effective catalytic active sites. The combined action between both contributes to the superior electrocatalytic performance.

Ruthenium Oxide Modified alpha‐Manganese Dioxide Nanotube as Efficient Bifunctional Cathode Catalysts for Lithium Oxygen Batteries

AbstractThe design and fabrication of cathode remain a major challenge for lithium oxygen (Li‐O2) batteries. Here, RuO2/α‐MnO2 nanotubes as efficient bifunctional cathode catalysts are prepared by two‐step hydrothermal reaction to improve the battery performance. Nitrogen adsorption desorption (BET) tests indicate that RuO2/α‐MnO2 nanotubes have mesoporous structure with specific surface area of 51.2 m2 g−1. Electrochemical tests show that the catalytic activity and the conductivity of α‐MnO2 nanotubes modified with RuO2 nanoparticles are improved. RuO2/α‐MnO2 nanotubes are used as a bifunctional electrocatalyst for cathode in Li‐O2 batteries, which show reduced overpotential, improved rate and cycling performance. At the current density of 0.05 mA cm−2, the overpotential of the batteries can go down by 0.38 V, and these batteries can be fully discharged/charged 26 cycles stably at a fixed capacity of 500 mAh g−1. The combination of RuO2 nanoparticles and α‐MnO2 nanotubes has excellent catalytic activity for ORR/OER, thus greatly improving the electrochemical performance of Li‐O2 batteries.

Atomic layered deposition iron oxide on perovskite LaNiO3 as an efficient and robust bi-functional catalyst for lithium oxygen batteries

The desirable physi-chemical properties of perovskite oxides make them the promising cathode materials of rechargeable Li-O2 batteries. Much attention is devoted to the structure design and the composite incorporation to develop the catalytic activity and durability of perovskite oxides used in the electrode. Herein, we propose an integration of atomic layered deposition iron oxide and perovskite LaNiO3 as a novel catalyst for both oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). Owing to the unique interconnected structure and the synergistic effect of Fe2O3 and LaNiO3, the 6 nm thick Fe2O3/LaNiO3 hybrid catalyst demonstrates the considerable intrinsic activities, which favorably outperforms other the state of the art perovskite catalysts. In addition, the Li-O2 battery employing this tailored catalyst displays a significantly decreased reduced discharge/charge voltage gap of 0.77 V at 50 mA g−1 with good rate capability and considerable cycle stability, indicating the practical feasibility of Fe2O3/LaNiO3 hybrid as a promising oxygen electrode catalyst for Li-O2 batteries. This study highlights a new and feasible scheme to promote the bi-functionally of perovskite catalysts for the development of Li-O2 batteries and other electrochemical devises.

Photo-enhanced lithium oxygen batteries with defective titanium oxide as both photo-anode and air electrode

The catalysts for lithium-oxygen batteries have been researched for decades due to the huge energy storage ability. However, the sluggish catalytic performance towards the decomposition of discharge products (Li2O2) inspires us to utilize the photo-generated holes to overcome the obstacle. As novel energy storage device, the TiO2 nanorod arrays on carbon textiles were well-designed and adopted as both air cathode and photo-anode for photo-assisted Li-O2 batteries. Electrochemical data strongly demonstrate that the abundant photo-generated holes on the TiO2 can efficiently oxidize the Li2O2 (the charge potential reduced from 4.31V to 2.86V vs Li/Li+). It is noted that the light illumination prompts the TiO2 to be more defective and the generated oxygen vacancies further enhance the electron and Li+ migration, leading to the improved ORR performance (discharge potential at 2.85V vs Li/Li+). The batteries can charge/discharge for 30 cycles with no decay and deliver the excellent rate performance.

Investigation of Electrochemical Performance of Li-O2 Batteries Using Catalyst Containing Carbon Nanotube Cathodes

Batteries with high specific energy densities have attracted a lot of attention due to their demand in electric vehicles (EVs). Due to the increase in demand for energy storage devices for applications such as load-levelling of electrical energy supply and demand propulsion for electric vehicles and microelectro-mechanical devices, the research for new classes of electrode materials that provide high energy, high power and cycle life longer than lithium-ion batteries is being motivated. Lithium air batteries have high specific energy density and they can achieve four times higher energy density than the current lithium ion batteries. The search for high energy density batteries has motivated the research in lithium-air batteries. Catalysts have been shown to improve both the battery capacity and the recyclability of these batteries when used in cathodes. Several catalysts have been discovered for lithium air batteries. Debart et al. used several catalysts for lithium oxygen batteries with non-aqueous electrolyte. The electro-catalysts used by them included Pt, La0.8Sr0.2MnO3, Fe2O3, NiO, CuO, CoFe2O4. Co3O4 exhibited highest discharge capacity and best cycling performance. Later Debart et al. examined manganese oxides as catalysts for lithium oxygen batteries. Mn3O4, bulk Mn2O3, bulk α, β, λ, γ-MnO2, α-MnO2 nanowires and β-MnO2 nanowires were used as catalysts. The air cathode with α-MnO2 as the catalyst showed the highest capacity of about 3000 mAh/g (carbon) Lu et al. reported ORR studies on polycrystalline metal catalysts of palladium, platinum, ruthenium, gold and glassy carbon surfaces in non-aqueous electrolyte. In our study, we investigate various modes of loading palladium-based catalysts and their effect on the capacity and round-trip efficiency of lithium-air batteries. Our aim is to increase the first discharge capacity, improve the recyclability, increase capacity retention and improve the recyclability of the battery. The loading and morphology the catalyst-CNT cathode is studied using transmission electron microscopy. Electrochemical testing using electrochemical impedance spectroscopy and charge-discharge cycling is also investigated. Voltammetry, Raman spectroscopy, FTIR, XRD, UV/Vis spectroscopy and visual inspection of the discharge products using scanning electron microscopy confirms the increased stability of the electrolyte due to this encapsulation and suggest that this approach could lead the increasing Li-O2 battery capacity and cyclability performance.

Low charge overpotentials and extended full cycling capability in lithium-oxygen batteries by controlling the nature of discharge products

Hollow NiCo2O4 microspheres with a highly hierarchical porous structure were synthesized and conducted as catalysts for lithium-oxygen batteries. The influence of NiCo2O4 on the discharge products was investigated. The NiCo2O4 showed the capability to promote the formation of lithium deficient Li2−xO2 and exerted a significant influence on the electrochemical performance of lithium-oxygen batteries with a low charge overpotential and extended full cycling over 50cycles.

Phthalocyanines Based Two-Phase Catalysts for Lithium Oxygen Batteries

Li-air batteries, which are considered to offer much higher energy density than the current Li-ion batteries suffer from poor cycle life due to electrolyte decomposition and clogging of the air cathode by insoluble discharge products. Efficient bifunctional catalysts could improve the stability of Li-air batteries by lowering the overpotential and prolonging the battery cycle life. This study focuses on Iron phthalocyanines (FePc) as possible bifunctional electrocatalysts. Metal phthalocyanines were utilized mainly because of their structural analogy which could be fine- tuned by the metal being used, accessibility, and low cost. In this work, firstly, FePc supported on graphite nanofibres (GNF) was investigated as solid electrocatalyst in non-aqueous LiTFSI (TEGDME) electrolyte. Secondly, FePc was dissolved in the non-aqueous electrolyte and studied as liquid catalyst with GNF cathode. FePc/GNF (solid catalyst) delivered superior electrocatalytic performance for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) comparable to that of commercial Pt/C. FePc_electrolyte (liquid catalyst) exhibited a steady profile for chronoamperometry, and good diffusivity of lithium ions as measured from electrochemical impedance spectroscopy. The bifunctional catalysts when applied as electrocatalysts in non-aqueous lithium air batteries delivered better electrochemical performance mainly by reducing the large overpotential associated with ORR and OER. Both the cells with solid and soluble FePc exhibited better reversibility and cyclability. The performance of FePc catalyst as solid and liquid has been comparative analyzed in detail.

Self-Assembled 3D Foam-Like NiCo2O4 as Efficient Catalyst for Lithium Oxygen Batteries.

A self-assembled 3D foam-like NiCo2O4 catalyst has been synthesized via a simple and environmental friendly approach, wherein starch acts as the template to form the unique 3D architecture. Interestingly, when employed as a cathode for lithium oxygen batteries, it demonstrates superior bifunctional electrocatalytic activities toward both the oxygen reduction reaction and the oxygen evolution reaction, with a relatively high round-trip efficiency of 70% and high discharge capacity of 10 137 mAh g(-1) at a current density of 200 mA g(-1), which is much higher than those in previously reported results. Meanwhile, rotating disk electrode measurements in both aqueous and nonaqueous electrolyte are also employed to confirm the electrocatalytic activity for the first time. This excellent performance is attributed to the synergistic benefits of the unique 3D foam-like structure and the intrinsically high catalytic activity of NiCo2O4 .

Multi-Wall Carbon Nanotubes As Cathodes for Lithium-Air Batteries: Effect of Catalysts and Additives

Batteries with high specific energy densities have attracted a lot of attention due to their demand in electric vehicles (EVs). Due to the increase in demand for energy storage devices for applications such as load-levelling of electrical energy supply and demand [1], propulsion for electric vehicles, and microelectro-mechanical devices, the research for new classes of electrode materials that provide high energy, high power and cycle life longer than lithium-ion batteries is being motivated [2,3]. Lithium air batteries have high specific energy density and they can achieve four times higher energy density than the current lithium ion batteries [2, 3]. Lithium air batteries also have higher theoretical energy density than lithium ion batteries [4]. Catalysts have been shown to improve both the battery capacity and the recyclability of these batteries when used in cathodes. Several catalysts have been discovered for lithium air batteries. Debart et al. used several catalysts for lithium oxygen batteries with non-aqueous electrolyte. The electro-catalysts used by them included Pt, La0.8Sr0.2MnO3, Fe2O3, NiO, CuO, CoFe2O4. Co3O4 exhibited highest discharge capacity and best cycling performance. Later Debart et al. examined manganese oxides as catalysts for lithium oxygen batteries. Mn3O4, bulk Mn2O3, bulk α, β, λ, γ-MnO2, α-MnO2 nanowires and β-MnO2 nanowires were used as catalysts [6]. The air cathode with α-MnO2 as the catalyst showed the highest capacity of about 3000 mAh/g (carbon) Lu et al. reported ORR studies on polycrystalline metal catalysts of palladium, platinum, ruthenium, gold and glassy carbon surfaces in non-aqueous electrolyte [5]. In this study, we investigate various modes of loading palladium-based catalysts and their effect on the capacity and round-trip efficiency of lithium-air batteries. The aim of our study is to increase the first discharge capacity, improve the recyclability, increase capacity retention and improve the recyclability of the battery. The loading and morphology the catalyst-CNT cathodes were studied using transmission electron microscopy. Electrochemical testing using electrochemical impedance spectroscopy and charge-discharge cycling were also investigated. The cathode consisted of conductive carbon cloth coated with MWCNT or palladium inside MWCNT. Celgard 2040 was used as a separator. LiTFSi (Bis Trifluoromethane sulfonamide Lithium salt) in TEGDME (Tetraethyl glycol di-methyl ether) was used as electrolyte. The battery was assembled in the Swagelok cell. Figure 1 shows the assembly of the battery. Figure 2 shows the TEM images of palladium nanoparticles inside MWCNT. Figure 3 shows Pristine CNT with first cycle at a current rate of 200 mA/g showing a discharge capacity of 9300 mAh/g and a charge capacity of 8250 mAh/g. Figure 4 shows catalyst-loaded CNT with first cycle at a current rate of 200 mA/g showing a discharge capacity of 13800 mAh/g and a charge capacity of 3000 mAh/g.