Hongbin Chen

Freestanding, Hydrophilic Nitrogen-Doped Carbon Foams for Highly Compressible All Solid-State Supercapacitors

Freestanding and highly compressible nitrogen-doped carbon foam (NCF) with excellent hydrophilicity and good electrochemical properties is prepared. Based on NCF electrodes, a high-performance all solid-state symmetric supercapacitor device is fabricated with native, full compressibility, and excellent mechanical stability, addressing two major problems in the current technology.

Graphene-based nitrogen-doped carbon sandwich nanosheets: a new capacitive process controlled anode material for high-performance sodium-ion batteries

Anode materials with capacitive charge storage (CCS) are highly desirable for the development of high-performance sodium-ion batteries (SIBs), because the capacitive process usually shows kinetically high ion diffusion and superior structural stability. Here, we report a new CCS anode material of graphene-based nitrogen-doped carbon sandwich nanosheets (G-NCs). The as-prepared G-NCs show a high capacitive contribution during the discharge/charge processes. As expected, the G-NCs exhibit excellent rate performance with a reversible capacity of 110 mA h g−1, even at a current as high as 10000 mA g−1, and outstanding cycle stability (a retention of 154 mA h g−1 after 10000 cycles at 5000 mA g−1). This represents the best cycle stability among all reported carbon anode materials for SIBs, thereby showing great potential as a commercial anode material for SIBs.

Nitrogen-doped bamboo-like carbon nanotubes: promising anode materials for sodium-ion batteries

Nitrogen-doped bamboo-like carbon nanotubes (N-BCNTs) were synthesised using a facile one-step pyrolysis process. Due to their unique one-dimensional hollow structure and intrinsic high nitrogen content, N-BCNTs exhibit high capacity, superior rate capability, and excellent cycle stability and are, thus, promising anode materials for sodium-ion batteries.

Hierarchical Mesoporous/Macroporous Perovskite La0.5Sr0.5CoO3–x Nanotubes: A Bifunctional Catalyst with Enhanced Activity and Cycle Stability for Rechargeable Lithium Oxygen Batteries

Perovskites show excellent specific catalytic activity toward both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in alkaline solutions; however, small surface areas of the perovskites synthesized by traditional sol-gel methods lead to low utilization of catalytic sites, which gives rise to poor Li-O2 batteries performance and restricts their application. Herein, a hierarchical mesporous/macroporous perovskite La0.5Sr0.5CoO3-x (HPN-LSC) nanotube is developed to promote its application in Li-O2 batteries. The HPN-LSC nanotubes were synthesized via electrospinning technique followed by postannealing. The as-prepared HPN-LSC catalyst exhibits outstanding intrinsic ORR and OER catalytic activity. The HPN-LSC/KB electrode displays excellent performance toward both discharge and charge processes for Li-O2 batteries, which enhances the reversibility, the round-trip efficiency, and the capacity of resultant batteries. The synergy of high catalytic activity and hierarchical mesoporous/macroporous nanotubular structure results in the Li-O2 batteries with good rate capability and excellent cycle stability of sustaining 50 cycles at a current density of 0.1 mA cm(-2) with an upper-limit capacity of 500 mAh g(-1). The results will benefit for the future development of high-performance Li-O2 batteries using hierarchical mesoporous/macroporous nanostructured perovskite-type catalysts.

Porous Na3V2(PO4)3@C nanoparticles enwrapped in three-dimensional graphene for high performance sodium-ion batteries

Porous Na3V2(PO4)3@C nanocomposites enwrapped in a 3D graphene network were prepared using a simple freeze-drying-assisted thermal treatment method. The carbon layer and 3D graphene network provide not only a 3D conductive network but also a double restriction on the aggregation of Na3V2(PO4)3 particles that have a high crystallinity under high temperature treatment. Due to the high electrochemical activity of the highly crystalline Na3V2(PO4)3 nanoparticles and 3D conductive network, the novel NVP@C/G material displays a superior rate capability (76 mA h g−1 at 60C) and ultra-long cyclability (82% capacity retention for 1500 cycles at 40C) when used in sodium-ion batteries.

Nitrogen-doped porous carbon derived from residuary shaddock peel: a promising and sustainable anode for high energy density asymmetric supercapacitors

Exploring high-performance negative electrode materials is one of the great challenges in the development of high-energy density asymmetric supercapacitors (ASCs). Herein, a new kind of high-performance nitrogen-doped nanoporous carbon (NPC) electrode with a large surface area and abundant micropores/mesopores was derived from conveniently available fruit waste (shaddock peel) via a facile pyrolysis process. Electrochemical measurements showed that the as-synthesized NPC electrodes possessed a remarkably large capacitance of 321.7 F g−1 with good rate capability and excellent long-term cycling stability. Such excellent electrochemical performance was achieved by shortening the diffusion distance, increasing the electrode–electrolyte contact area and improving the electron conductivity of the NPC electrode arising from its nanoporous architecture and nitrogen doping. As a prototype, an all-solid-state ASC device based on the NPC negative electrode and a MnO2 positive electrode achieved an ultrahigh energy density of 82.1 W h kg−1 at a power density of 899 W kg−1, which is considerably larger than most reported carbon based supercapacitor devices.

Novel nitrogen-rich porous carbon spheres as a high-performance anode material for lithium-ion batteries

Carbonaceous materials with suitable structure and components are highly desirable for the development of lithium ion batteries (LIBs), since they can produce the best possible result by combining the advantages of the various structures and different components. To this end, herein, novel nitrogen-rich porous carbon spheres (N-PCS) with an appropriate pores distribution are proposed and prepared by using a template-assisted self-assembly method. The as-prepared N-PCS possess a high nitrogen content (>5%) and exhibit an interconnected sphere structure with large quantities of mesopores. As expected, the N-PCS display superior electrochemical performances, such as a high initial columbic efficiency (>60%), super cycle stability (retention of 540 mA h g−1 after 100 cycles at 0.5 A g−1), and good rate capability (215 mA h g−1 at 3 A g−1), thereby showing great promise as anode materials for the next generation of LIBs.

Self‐Supported PtAuP Alloy Nanotube Arrays with Enhanced Activity and Stability for Methanol Electro‐Oxidation

Inhibiting CO formation can more directly address the problem of CO poisoning during methanol electro-oxidation. In this study, 1D self-supported porous PtAuP alloy nanotube arrays (ANTAs) are synthesized via a facile electro-codeposition approach and present enhanced activity and improved resistance to CO poisoning through inhibiting CO formation (non-CO pathway) during the methanol oxidation reaction in acidic medium. This well-controlled Pt-/transition metal-/nonmetal ternary nanostructure exhibits a specific electroactivity twice as great as that of PtAu alloy nanotube arrays and Pt/C. At the same time, PtAuP ANTAs show a higher ratio of forward peak current density (If ) to backward peak current density (Ib ) (2.34) than PtAu ANTAs (1.27) and Pt/C (0.78). The prominent If /Ib value of PtAuP ANTAs indicates that most of the intermediate species are electro-oxidized to carbon dioxide in the forward scan, which highlights the high electroactivity for methanol electro-oxidation.

Highly Compressible Nitrogen-Doped Carbon Foam Electrode with Excellent Rate Capability via a Smart Etching and Catalytic Process

Freestanding three-dimensional nitrogen-doped carbon foam with large pores is proposed as a promising electrode configuration for elastic electronics. Although it exhibits excellent mechanical performance, the capacitive performances (especially its rate capability) are still unsatisfactory. By using KMnO4, we demonstrate a smart etching and catalytic process to form highly graphitized and etched nitrogen-doped carbon foam (ENCF) with an exfoliated carbon-shell architecture. These compositional and structural features endow the ENCF electrodes with excellent electron conductivity as well as more ion-accessible electrochemical active sites. Significantly, all-solid-state symmetric supercapacitor devices based on the ENCF electrodes exhibit enhanced specific capacitance and marked high-rate capability. Furthermore, the integrated device has no significant capacity loss under 60% compressive strain.

Highly ordered ZnMnO3 nanotube arrays from a “self-sacrificial” ZnO template as high-performance electrodes for lithium ion batteries

Highly ordered ZnMnO3 nanotube arrays (ZnMnO3 NTAs) are prepared by an electro-deposition strategy in the presence of “self-sacrificial” ZnO templates. The ZnMnO3 NTA electrode exhibits excellent cycling performance (857.5 mA h g−1 after 200 cycles at 500 mA g−1) and superior rate capability (208.3 mA h g−1 after 200 cycles at 5000 mA g−1). The excellent electrochemical performance should be mainly attributed to its “mixed” chemical compositions and hollow nanotube array morphologies.