Peng Gu

Facile synthesis of an accordion-like Ni-MOF superstructure for high-performance flexible supercapacitors

Metal–organic frameworks have received increasing attention as promising electrode materials in supercapacitors. In this study, we have successfully synthesized a novel accordion-like Ni-MOF superstructure ([Ni3(OH)2(C8H4O4)2(H2O)4]·2H2O), for the first time, and used it as an electrode material for supercapacitors. The supercapacitors with the novel electrode exhibited excellent electrochemical performance. For example, the accordion-like Ni-MOF electrode showed specific capacitances of 988 and 823 F g−1 at current densities of 1.4 and 7.0 A g−1, respectively, while maintaining outstanding cycling stability (capacitance retention of 96.5% after 5000 cycles at a current density of 1.4 A g−1). More importantly, the accordion-like Ni-MOF and activated carbons were assembled into a high-performance flexible solid-state asymmetric supercapacitor with a specific capacitance of 230 mF cm−2 at a current density of 1.0 mA cm−2. The cycle test showed that the device can offer 92.8% capacity of the initial capacitance at 5.0 mA cm−2 after 5000 cycles with little decay. The maximum energy density of the device can achieve 4.18 mW h cm−3 and the maximum power density can also achieve 231.2 mW cm−3.

Transition metal oxides with one-dimensional/one-dimensional-analogue nanostructures for advanced supercapacitors

With the increasing energy demand and the overconsumption of fossil fuels, renewable energy-storage devices with higher efficiency are of great interest. In particular, supercapacitors have recently gained significant attention due to their excellent charge–discharge performance, long-term cycle lifetimes, and high specific power. In addition, supercapacitors could also make up the difference in energy and power between batteries and traditional capacitors. In the future, the promising family of transition metal oxides (TMOs) will play a significant role in environmentally friendly, low-cost, and high-powered energy storage. Furthermore, one-dimensional (1D) and one-dimensional-analogue nanostructures could remarkably enhance the characteristic properties of TMOs. In this review, we focused on the recent progress in the preparation and electrochemical properties of the next-generation supercapacitors.

Rechargeable zinc–air batteries: a promising way to green energy

As a promising technology, electrically rechargeable zinc–air batteries have gained significant attention in the past few years. Herein, in this review, we focused on the main challenges of the electrically rechargeable zinc–air batteries in alkaline electrolytes and the up-to-date progress from materials to technologies towards overcoming these technical barriers. We first overviewed the design and working mechanism of the battery and classified the hindrances into dendritic growth at the anode, lack of higher performance bifunctional catalysts at the air electrode, and electrolyte-related problems. Then, detailed discussions have been provided on the latest progress to address these technical issues based on the nano/micro-materials. Flexible zinc–air batteries as a new development have also been discussed in a separate section. Finally, conclusions have been provided followed by future perspective.

High performance of electrochemical lithium storage batteries: ZnO-based nanomaterials for lithium-ion and lithium–sulfur batteries

As one of the most promising electrode materials, zinc oxide-based nanomaterials have attracted great attention in recent decades for remarkable features such as relatively low cost, relatively high reversible capacity and good physical and chemical stability. In this article, we aim to present a general review of synthetic methods of zinc oxide-based nanomaterials and related morphologies. In addition, recent advances in lithium storage batteries are summarized and discussed (lithium-ion and lithium-sulfur batteries). Tentative conclusions and assessments aim to promote the next generation of electrochemical lithium storage devices.

Ultrathin Nanosheet Assembled Sn0.91Co0.19S2 Nanocages with Exposed (100) Facets for High-Performance Lithium-Ion Batteries

Ultrathin 2D inorganic nanomaterials are good candidates for lithium-ion batteries, as well as the micro/nanocage structures with unique and tunable morphologies. Meanwhile, as a cost-effective method, chemical doping plays a vital role in manipulating physical and chemical properties of metal oxides and sulfides. Thus, the design of ultrathin, hollow, and chemical doped metal sulfides shows great promise for the application of Li-ion batteries by shortening the diffusion pathway of Li ions as well as minimizing the electrode volume change. Herein, ultrathin nanosheet assembled Sn0.91 Co0.19 S2 nanocages with exposed (100) facets are first synthesized. The as-prepared electrode delivers an excellent discharge capacity of 809 mA h g-1 at a current density of 100 mA g-1 with a 91% retention after 60 discharge-charge cycles. The electrochemical performance reveals that the Li-ion batteries prepared by Sn0.91 Co0.19 S2 nanocages have high capacity and great cycling stability.