Flexible NiO-Graphene-Carbon Fiber Mats Containing Multifunctional Graphene for High Stability and High Specific Capacity Lithium-Ion Storage

Metal-Organic Framework-Derived Trimetallic Nanocomposites as Efficient Bifunctional Oxygen Catalysts for Zinc-Air Batteries

Transition-metal-based multifunctional catalysts have attracted increasing attention owing to high possibilities of substituting the expensive noble-metal-based catalysts in various scenarios. Multivariate metal-organic frameworks (MTV-MOFs) are ideal precursors to prepare multimetallic nanocomposites with high catalytic activity since the uniform distribution and precise regulation of mixed metal centers, as well as the consequent strong synergistic effect, could be readily achieved. Herein, a Mn/Co/Ni trimetallic catalyst (MnCoNi-C-D) with a hollow rhombic dodecahedron shape was synthesized via pyrolysis of the corresponding trimetallic-based MTV-MOF. The catalyst shows outstanding electrochemical activity toward the oxygen reduction reaction including a half-wave potential of 0.82 V and superior tolerance against methanol as well as high stability in an alkaline medium, and its oxygen evolution reaction activity also surpasses a RuO₂ catalyst. Moreover, primary and rechargeable zinc-air batteries based on MnCoNi-C-D delivered preferable performances compared with commercial Pt/C-RuO₂, including higher peak power density (116.4 mW cm^-2), higher specific capacity (841.3 mAh g^-1), higher open-circuit potential (OCV) (1.46 V), and better stability for more than 180 h. A comprehensive comparison was also conducted to prove the necessity of employing the MTV-MOF as the precursor and investigate the intrinsic superiority of the catalyst.

Precise synthesis of pillared graphene nanosheets with superior potassium storage via an in situ growth strategy

We report a simple in situ growth strategy to synthesize pillared graphene nanosheets with an expanded interlayer spacing. The graphene nanosheet/NiO-500 composite assembled binder-free flexible anode shows excellent potassium storage performance.

Carboxyl functionalized carbon incorporation of stacked ultrathin NiO nanosheets: topological construction and superior lithium storage

Two-dimensional (2D) nanostructure engineering and surface modification with functional groups are of great importance to anode materials for rechargeable lithium-ion batteries. Herein, stacked NiO nanosheets@carbon (denoted as NiO@C) and 3 nm-ultrathin NiO nanosheets@functionalized carbon with surface functional groups NO3-, CO32-, OH-, and COOH- (denoted as NiO@FC) were prepared via a facile one-pot reaction and topotactic conversion. Specifically, NiO@FC exhibits excellent lithium storage performance: the capacity of NiO@FC is 489.2 mA h g-1, higher than that of NiO@C (1018.7 mA h g-1 at 0.2 A g-1), and maintains a capacity of 1133 mA h g-1 after 800 cycles, which exceed that of all previously reported NiO anodes. The enhanced lithium storage performance is attributed to the sufficient void space, which offers buffer space for volume change and speeds up the diffusion of Li+ ions. In addition, the surface functional groups were proved to not only hinder the agglomeration of nanosheets but also further donate active sites and improve storage capacity. These advantageous features achieved by designing such a stacked structure with functionalized carbon modification provide a promising strategy for the preparation of high-performance anode materials and other 2D functional materials.

Nix Mny Coz O Nanowire/CNT Composite Microspheres with 3D Interconnected Conductive Network Structure via Spray-Drying Method: A High-Capacity and Long-Cycle-Life Anode Material for Lithium-Ion Batteries

The combination of high-capacity and long-term cycling stability is an important factor for practical application of anode materials for lithium-ion batteries. Herein, Ni_x Mn_y Co_z O nanowire (x + y + z = 1)/carbon nanotube (CNT) composite microspheres with a 3D interconnected conductive network structure (3DICN-NCS) are prepared via a spray-drying method. The 3D interconnected conductive network structure can facilitate the penetration of electrolyte into the microspheres and provide excellent connectivity for rapid Li⁺ ion/electron transfer in the microspheres, thus greatly reducing the concentration polarization in the electrode. Additionally, the empty spaces among the nanowires in the network accommodate microsphere volume expansion associated with Li⁺ intercalation during the cycling process, which improves the cycling stability of the electrode. The CNTs distribute uniformly in the microspheres, which act as conductive frameworks to greatly improve the electrical conductivity of the microspheres. As expected, the prepared 3DICN-NCS demonstrates excellent electrochemical performance, showing a high capacity of 1277 mAh g^-1 at 1 A g^-1 after 2000 cycles and 790 mAh g^-1 at 5 A g^-1 after 1000 cycles. This work demonstrates a universal method to construct a 3D interconnected conductive network structure for anode materials.

Nitrogen doped small molecular structures of nano-graphene for high-performance anodes suitable for lithium ion storage

N-doped nano-graphene derivatives were prepared by a bottom-up organic synthesis method.

Hierarchical non-woven fabric NiO/TiO2 film as an efficient anode material for lithium-ion batteries

Positive synergistic effect of TiO₂ and NiO of NiO/TiO₂ non-woven fabric electrode improves the electrochemical performance.

Construction of 3D architectures with Ni(HCO3)2 nanocubes wrapped by reduced graphene oxide for LIBs: ultrahigh capacity, ultrafast rate capability and ultralong cycle stability

A 3D layered Ni(HCO₃)₂/rGO nano-architecture was fabricated by coordination self-assembly for high performance storage of Li-ions with fast electrode kinetics and a super-long life.

Rechargeable lithium-ion batteries (LIBs) have been the dominating technology for electric vehicles (EV) and grid storage in the current era, but they are still extensively demanded to further improve energy density, power density, and cycle life. Herein, a novel 3D layered nanoarchitecture network of Ni(HCO₃)₂/rGO composites with highly uniform Ni(HCO₃)₂ nanocubes (average diameter of 100 ± 20 nm) wrapped in rGO films is facilely fabricated by a one-step hydrothermal self-assembly process based on the electrostatic interaction and coordination principle. Benefiting from the synergistic effects, the Ni(HCO₃)₂/rGO electrode delivers an ultrahigh capacity (2450 mA h g^–1 at 0.1 A g^–1), ultrafast rate capability and ultralong cycling stability (1535 mA h g^–1 for the 1000^th cycle at 5 A g^–1, 803 mA h g^–1 for the 2000^th cycle at 10 A g^–1). The detailed electrochemical reaction mechanism investigated by in situ XRD further indicates that the 3D architecture of Ni(HCO₃)₂/rGO not only provides a good conductivity network and has a confinement effect on the rGO films, but also benefits from the reversible transfer from LiHCO₃ to Li_xC₂ (x = 0–2), further oxidation of nickel, and the formation of a stable/durable solid electrolyte interface (SEI) film (LiF and LiOH), which are responsible for the excellent storage performance of the Li-ions. This work could shed light on the design of high-capacity and low-cost anode materials for high energy storage in LIBs to meet the critical demands of EV and mobile information technology devices.

Functionalized Graphene Quantum Dot Modification of Yolk-Shell NiO Microspheres for Superior Lithium Storage

Yolk-shell NiO microspheres are modified by two types of functionalized graphene quantum dots (denoted as NiO/GQDs) via a facile solvothermal treatment. The modification of GQDs on the surface of NiO greatly boosts the stability of the NiO/GQD electrode during long-term cycling. Specifically, the NiO with carboxyl-functionalized GQDs (NiO/GQDsCOOH) exhibits better performances than NiO with amino-functionalized GQDs (NiO/GQDsNH₂ ). It delivers a capacity of ≈1081 mAh g^-1 (NiO contribution: ≈1182 mAh g^-1 ) after 250 cycles at 0.1 A g^-1 . In comparison, NiO/GQDsNH₂ electrode holds ≈834 mAh g^-1 of capacity, while the bald NiO exhibits an obvious decline in capacity with ≈396 mAh g^-1 retained after cycling. Except for the yolk-shell and mesoporous merits, the superior performances of the NiO/GQD electrode are mainly ascribed to the assistance of GQDs. The GQD modification can support as a buffer alleviating the volume change, improve the electronic conductivity, and act as a reservoir for electrolytes to facilitate the transportation of Li⁺ . Moreover, the enrichment of carboxyl/amino groups on GQDs can further donate more active sites for the diffusion of Li⁺ and facilitate the electrochemical redox kinetics of the electrode, thus together leading to the superior lithium storage performance.

Graphitic carbon-wrapped NiO embedded three dimensional nitrogen doped aligned carbon nanotube arrays with long cycle life for lithium ion batteries

In this work, a three-dimensional nitrogen doped aligned carbon nanotube array (NACNTs)@NiO@graphitic carbon composite was fabricated by an effective strategy involving nebulized ethanol assisted infiltration, In this structure, the NiO nanoparticles were wrapped by graphitic carbon layers and NiO@graphitic carbon core–shell nanoparticles adhered strictly to the surface of NACNTs to form a highly ordered 3D structure. When this composite was used as an anode for lithium ion batteries, the well-ordered pore of its NACNTs can facilitate the electrolyte to penetrate and improve electronic conductivity. At the same time, the graphitic layers can promote the stability of a solid electrolyte interface film. Therefore, the NACNTs@NiO@graphitic carbon composite containing 68.1 wt% NiO delivers excellent capacity retention of 91.6% after 200 cycles at 0.2C.

NACNTs@NiO@graphitic carbon composites were synthesized with the help of nebulizing. The outstanding performances are attributed to the original structure of NACNTs@NiO@graphitic carbon.