Encapsulation of Sulfur into N‐Doped Porous Carbon Cages by a Facile, Template‐Free Method for Stable Lithium‐Sulfur CathodeZeng, Shuaibo; Arumugam, Gowri Manohari; Liu, Xianhu; Yang, Yuzhao; Li, Xin; Zhong, Hai; Guo, Fei; Mai, Yaohua
doi: 10.1002/smll.202001027pmid: 32856390
Lithium‐sulfur (Li‐S) batteries with a high energy density and long lifespan are considered as promising candidates for next‐generation electrochemical energy‐storage devices. However, the sluggish redox kinetics of electrochemistry and high solubility of polysulfide during cycling render insufficient sulfur utilization and poor cycling stability. Herein, a facile, template‐free procedure based on controlled pyrolysis of polydopamine vesicles is described to prepare N‐doped porous carbon cages (NHSC) as a new sulfur host, which significantly improves both the sulfur utilization and cycling stability. As NHSC shows a high pore volume, continuous electron and ion transport paths, and good catalytic activity, encapsulation of S nanoparticles into NHSC endows the resulting S@NHSC electrode with a good energy storage capacity and exceptionally high electrochemical stability. Consequently, a Li‐S cell with the S@NHSC as the cathode achieves a high initial capacity of 1280.7 mAh g−1, and cycling stability over 500 cycles with the capacity decay as low as 0.0373% per cycle.
Recent Advances in High‐Performance Microbatteries: Construction, Application, and PerspectiveZhu, Zhe; Kan, Ruyu; Hu, Song; He, Liang; Hong, Xufeng; Tang, Hui; Luo, Wen
doi: 10.1002/smll.202003251pmid: 32870600
High‐performance miniaturized energy storage devices have developed rapidly in recent years. Different from conventional energy storage devices, microbatteries assume the main responsibility for micropower supply, functionalization, and characterization platforms. Evolving from the essential goals for battery design of high power density, high energy density, and long lifetime, further practical demands for microbatteries (MBs) have been raised for the microfabrication technique and device design. Numerous studies have generally focused on specific aspects of the microelectrode structures or certain microfabrication techniques, while the connection from techniques to functional applications is rarely involved. This Review generally fills such blanks from an application‐oriented perspective. First, some basic micromachining techniques with different compatible features are summarized. Afterward, device designs including diversified battery reaction types, configuration, and assembly are highlighted, as well as microbatteries serving powering resources or further complicated functional systems. Finally, through providing the overall design concept based on requirements in application, this Review offers innovative insights for further development of microbatteries.
Cucurbit[6]uril‐Derived Sub‐4 nm Pores‐Dominated Hierarchical Porous Carbon for Supercapacitors: Operating Voltage Expansion and Pore Size MatchingQiu, Daping; Li, Min; Kang, Cuihua; Wei, Jinying; Wang, Feng; Yang, Ru
doi: 10.1002/smll.202002718pmid: 32830405
The intrinsic properties of carbon‐based material and the voltage window of electrolyte are the two key barriers to restrict the energy density of carbon‐based supercapacitors (SCs). Herein, a cucurbit[6]uril‐derived nitrogen‐doped hierarchical porous carbon (CBCx) with unique pore structure characteristics is synthesized and successfully applied to construct SCs based on different electrolyte systems. Owing to narrow pore size distribution (0.5–4 nm), colossal ion‐accessible pore volume, prominent supermesopore volume, and reasonable heteroatom configuration, the CBCx‐based SCs demonstrate excellent electrochemical performances with high operating voltages in two distinct systems. The optimal SCs can output a maximum energy/power density of 18 Wh kg−1 (11.1 Wh L−1)/20 kW kg−1 (12.3 kW L−1) with an operating voltage of 1.2 V in potassium hydroxide aqueous electrolyte, as well as an ultralong cycle life of up to 50 000 cycles (0.046% decay per 100 cycles). Furthermore, the optimal SCs deliver an exceptionally high energy/power density of 95 Wh kg−1 (58.4 Wh L−1)/70 kW kg−1 (43 kW L−1) with an ultrahigh operating voltage of 3.5 V in 1‐ethyl‐3‐methylimidazolium tetrafluoroborate electrolyte. This work opens up a new application field for cucurbit[6]uril and provides an alternative avenue for optimizing the performances of carbon‐based materials for SCs.
Disposable 3D GNAs/AuNPs DNA‐Circuit Strip for miRNAs Dynamic QuantificationBao, Jing; Qiu, Xiaopei; Yang, Huisi; Lu, Wenqiang; Yang, Mei; Gu, Wei; Wu, Lixiang; Huo, Danqun; Luo, Yang; Hou, Changjun
doi: 10.1002/smll.202001416pmid: 32865862
Real‐time quantitative monitoring of miRNAs plays an essential role in diagnosis and therapeutics. Herein, a DSN‐coupled graphene nanoarray/gold nanoparticles (GNAs/AuNPs) carbon paper (CP) electrode for the dynamic, sensitive, and real‐time analysis of miRNAs is reported. GNAs are vertically grown on the conductive CP by radio frequency plasma enhanced chemical vapor deposition, and AuNPs are electrodeposited on CP/GNAs to build a 3D ultrasensitive sensing interface with large specific surface area, good conductivity and biocompatibility. The dynamic quantitative monitoring of microRNA‐21 (miR‐21) is realized by cyclic voltammetry with a series of different concentrations within 16 min, and this 3D GNAs/AuNPs DNA‐circuit strip shows good performance for the simultaneous detection of miR‐21 and miR‐155, and the detection limits are as low as 21.4 and 30.3 am, respectively. Moreover, comparable detection results are achieved for clinical samples between the proposed sensor and qRT‐PCR, suggesting the reliability of the constructed sensor. This ultrasensitive sensing and disposable DNA‐circuit strip with 3D structure can efficiently shorten the diffusion distance between reactive biomolecules and the sensing interface, enhance the hybridization of probes and improve the sensitivity of the biosensor, holding great promise for the rapid, quantitative and dynamic monitoring of multiple low concentrations of biomolecules in point‐of‐care clinical analysis.
A Novel Hierarchical Nanostructure for Enhanced Optical Nonlinearity Based on Scattering MechanismPang, Chi; Li, Rang; Li, Ziqi; Dong, Ningning; Ren, Feng; Wang, Jun; Chen, Feng
doi: 10.1002/smll.202003172pmid: 32877018
Surface modification of nonlinear optical materials (NOMs) is widely applied to fabricate diverse photonic devices, such as frequency combs, modulators, and all‐optical switches. In this work, a double‐layer nanostructure with heterogeneous nanoparticles (NPs) is proposed to achieve enhanced third‐order optical nonlinearity of NOMs. The mechanism of modified optical nonlinearity is elucidated to be the scattering‐induced energy transfer between adjacent NPs layers. Based on the LiNbO3 platform, as a typical example, double layers of embedded Cu and Ag NPs are synthesized by sequential ion implantation, demonstrating twofold magnitude of near‐infrared enhancement factor and modulation depth in comparison with a single layer of Cu NPs. With the elastic collision model and thermolysis theory being considered, the shift of the localized surface plasmon resonance (LSPR) peak reveals the formation mechanism of the double‐layer nanostructure. Utilizing the enhanced optical nonlinearity of LiNbO3 as modulators, a Q‐switched mode‐locked waveguide laser at 1 µm is achieved with shorter pulse duration. It suggests potential applications to improve the performance of nonlinear photonic devices by using double‐layer metallic nanostructures.