Sainan Liu

Nitrogen-doped TiO2 nanospheres for advanced sodium-ion battery and sodium-ion capacitor applications

Sodium-ion batteries (NIBs) and sodium-ion capacitors (NICs) are considered to be promising energy storage systems for applications in future hybrid electric vehicles (HEVs) and electric vehicles (EVs) because of the low cost and abundance of Na. Herein, NIBs and NICs based on nitrogen-doped TiO2 (referred to as N-TiO2) nanospheres as anode materials were analyzed. The N-TiO2 nanospheres exhibited a stable capacity of 162 mA h g−1 over 1000 cycles at 1 A g−1, as well as a superior rate performance in NIBs. In NICs, the N-TiO2//AC device displayed a high energy density of ∼80.3 W h kg−1, a high power density of ∼12 500 W kg−1, and excellent long-term cycling stability for up to 6500 cycles.

Metal–organic framework-templated two-dimensional hybrid bimetallic metal oxides with enhanced lithium/sodium storage capability

Two-dimensional (2D) porous hybrid bimetallic transition metal oxide (TMO) nanosheets demonstrated promising applications in the energy field due to their large surface areas, porous structure, and synergistic effects. However, the synthesis of these materials is still a big challenge. In this study, we rationally designed a facile strategy to prepare 2D porous hybrid bimetallic TMO (Co3O4/ZnO) nanosheets with novel structural and electrochemical synergistic effects. Derived from bimetallic MOF nanosheets, the porous hybrid nanosheets possess high surface areas and large pore volume. In particular, they are rich in oxygen vacancies, which provide more active sites for electrochemical reaction. Moreover, the harmonious multi-step conversion reaction between Co3O4 and ZnO was helpful for volume buffering, leading to an outstanding cyclic stability. With remarkable structural features and harmonious electrochemical behaviors, the Co3O4/ZnO hybrids exhibit excellent electrochemical performances as anodes for both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). This study also introduces a new strategy to prepare 2D porous hybrid bimetallic TMO nanosheets, which can find wide applications in energy storage, catalysis, sensors, and information storage devices.

High-performance sodium-ion batteries and flexible sodium-ion capacitors based on Sb2X3 (X = O, S)/carbon fiber cloth

Due to limited Li resources, sodium-ion batteries (NIBs) have become promising candidates for application in large-scale energy storage systems, and the development of high-performance anode materials for NIBs has become particularly urgent. Moreover, sodium-ion capacitors (NICs), which combine the characteristics of batteries and capacitors, have attracted significant research interest due to their high energy and power density. Herein, we report the design of efficient hydrothermal routes for synthesizing interlaced Sb2O3 nanosheets and Sb2S3 micro-nanospheres, grown on carbon fiber cloth, referred to as SO/CFC and SS/CFC, respectively, which were then used as flexible electrodes for NIBs and NICs devices. For NIBs applications, the SO/CFC electrodes exhibit a high stable capacity of 514 mA h g−1 after 500 cycles at 0.5 A g−1. The SS/CFC electrodes also display a stable capacity of 736 mA h g−1 after 650 cycles at 0.5 A g−1 and the high-rate capability can reach a high current density of 15 A g−1. Importantly, the flexible NIC device based on SO/CFC or SS/CFC as the anode and carbon fibers as the cathode was demonstrated, which manifests high power density and energy density, as well as significantly superior cycle stability.

Nb2O5 quantum dots embedded in MOF derived nitrogen-doped porous carbon for advanced hybrid supercapacitor applications

Hybrid supercapacitors (HSCs), which are expected to possess the good characteristics of both lithium batteries and supercapacitors, have become a hot research topic in recent years for catering to the growing market for electric vehicles (EVs) and hybrid electric vehicles (HEVs). Herein, we demonstrate an advanced hybrid material construction by the orthorhombic Nb2O5 quantum dots embedded in nitrogen-doped porous carbon derived from ZIF-8 dodecahedrons, referred to as NQD–NC. Then the applications of this material in LIBs and HSCs are studied in-depth. The LIB test reveals that the novel Nb2O5-based material shows excellent high-rate capability and long-term cyclic stability. Importantly, by assembling a HSC device using a NQD–NC anode and a commercial activated carbon cathode with an organic electrolyte, the HSC shows superior electrochemical performance including ultra-high energy and power density (76.9 W h kg−1 and 11 250 W kg−1, respectively) and superior cyclic stability (capacity retention of ∼85% at 5 A g−1 after 4500 cycles in a voltage range of 0.5–3.0 V). The excellent electrochemical performance of the HSCs indicates combining the advantages of lithium-ion batteries and supercapacitors, which is promising for the next generation of energy storage systems.

Nb2O5 microstructures: a high-performance anode for lithium ion batteries.

We report the synthesis of three-dimensional (3D) urchin-like Nb2O5 microstructures by a facile hydrothermal approach with subsequent annealing treatment. As anode materials for lithium-ion batteries, the 3D urchin-like Nb2O5 microstructures exhibit superior electrochemical performance with excellent rate capability as well as long-term cycling stability. The electrode delivers high capacity of 131 mA h g-1 after 1000 cycles at a high current density of 1 A g-1. The excellent electrochemical performance suggests the 3D urchin-like Nb2O5 microstructures may be a promising anode candidate for high-power lithium ion batteries.

Metal-organic framework-derived porous shuttle-like vanadium oxides for sodium-ion battery application

Vanadium oxides with a layered structure are promising candidates for both lithium-ion batteries and sodium-ion batteries (SIBs). The self-template approach, which involves a transformation from metal-organic frameworks (MOFs) into porous metal oxides, is a novel and effective way to achieve desirable electrochemical performance. In this study, porous shuttle-like vanadium oxides (i.e., V2O5, V2O3/C) were successfully prepared by using MIL-88B (V) as precursors with a specific calcination process. As a proof-of-concept application, the asprepared porous shuttle-like V2O3/C was used as an anode material for SIBs. The porous shuttle-like V2O3/C, which had an inherent layered structure with metallic behavior, exhibited excellent electrochemical properties. Remarkable rate capacities of 417, 247, 202, 176, 164, and 149 mAh·g−1 were achieved at current densities of 50, 100, 200, 500, 1,000, and 2,000 mA·g−1, respectively. Under cycling at 2 A·g−1, the specific discharge capacity reached 181 mAh·g−1, with a low capacity fading rate of 0.032% per cycle after 1,000 cycles. Density functional theory calculation results indicated that Na ions preferred to occupy the interlamination rather than the inside of each layer in the V2O3. Interestingly, the special layered structure with a skeleton of dumbbell-like V–V bonds and metallic behavior was maintained after the insertion of Na ions, which was beneficial for the cycle performance. We consider that the MOF precursor of MIL-88B (V) can be used to synthesize other porous V-based materials for various applications.