Figure 2. Illustration of the crystal structures of the main cathode materials: a) LiFePO 4 with olivine structure, b) LiMn 2 O 4 with spinel structure, and c) LiNi 0.5 Co 0.2 Mn 0.3 O 2 with layered structure. d) Comparison of energy density for typical cathode materials. a,b,d) Reproduced with permission. [55]

No abstract

A sandwichlike magnesium silicate/reduced graphene oxide nanocomposite (MgSi/RGO) with high adsorption efficiency of organic dye and lead ion was synthesized by a hydrothermal approach. MgSi nanopetals were formed in situ on both sides of RGO sheets. The nanocomposite with good dispersion of nanopetals exhibits a high specific surface area of 450 m(2)/g and a good mass transportation property. Compared to MgSi and RGO, the mechanical stability and adsorption capacity of the nanocomposite is significantly improved due to the synergistic effect. The maximum adsorption capacities for methylene blue and lead ion are 433 and 416 mg/g, respectively.

The ability to create highly efficient and stable bifunctional electrocatalysts, capable of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in the same electrolyte, represents an important endeavor toward high-performance zinc-air batteries (ZABs). Herein, we report a facile strategy for crafting wrinkled MoS2/N-doped carbon core/shell nanospheres interfaced with single Fe atoms (denoted MoS2@Fe-N-C) as superior ORR/OER bifunctional electrocatalysts for robust wearable ZABs with a high capacity and outstanding cycling stability. Specifically, the highly crumpled MoS2 nanosphere core is wrapped with a layer of single-Fe-atom-impregnated, N-doped carbon shell (i.e., Fe-N-C shell with well-dispersed FeN4 sites). Intriguingly, MoS2@Fe-N-C nanospheres manifest an ORR half-wave potential of 0.84 V and an OER overpotential of 360 mV at 10 mA⋅cm−2. More importantly, density functional theory calculations reveal the lowered energy barriers for both ORR and OER, accounting for marked enhanced catalytic performance of MoS2@Fe-N-C nanospheres. Remarkably, wearable ZABs assembled by capitalizing on MoS2@Fe-N-C nanospheres as an air electrode with an ultralow area loading (i.e., 0.25 mg⋅cm−2) display excellent stability against deformation, high special capacity (i.e., 442 mAh⋅g−1Zn), excellent power density (i.e., 78 mW⋅cm−2) and attractive cycling stability (e.g., 50 cycles at current density of 5 mA⋅cm−2). This study provides a platform to rationally design single-atom-interfaced core/shell bifunctional electrocatalysts for efficient metal-air batteries.

Low conductivity and tin coarsening issues hinder the utility of tin dioxide as anode for lithium and sodium ion batteries. To significantly advance the electrochemical performance and systematically unfold the energy storage mechanism of SnO2, monodisperse poly(ethylene glycol)‐ligated SnO2 nanoparticles are in situ crafted with star‐like poly(acrylic acid)‐block‐poly(ethylene glycol) diblock copolymers as nanoreactors and uniformly confined in layer‐by‐layer stacked graphene oxide matrix (denoted SnO2@PEG‐GO). Remarkably, SnO2@PEG‐GO nanohybrids manifest fully reversible three‐step lithiation‐delithiation reactions of SnO2 with an ultrahigh 100th discharge capacity of 1523 mAh g−1 at 100 mA g−1. Moreover, SnO2@PEG‐GO nanohybrids exhibit an ultrastable sodium storage capacity of 527 mAh g−1 after 500 cycles at 50 mA g−1, and the conversion reaction between Sn and SnO is uncovered as the primary reversible sodiation–desodiation reaction of SnO2. Notably, in addition to buffering volume expansion of SnO2 nanoparticles, the synergy between PEG and GO promotes Li+ or Na+ ion and electron transfers and inhibits Sn coarsening at micro and macro scales. This work provides a robust strategy to realizing outstanding electrochemical properties and scrutinizing fundamental mechanisms that underpin the performance of active materials via surface polymer ligation, precise size control, and uniform graphene encapsulation.

Lithium–sulfur batteries (LSBs) hold great promise as one of the next‐generation power supplies for portable electronics and electric vehicles due to their ultrahigh energy density, cost effectiveness, and environmental benignity. However, their practical application has been impeded owing to the electronic insulation of sulfur and its intermediates, serious shuttle effect, large volume variation, and uncontrollable formation of lithium dendrites. Over the past decades, many pioneering strategies have been developed to address these issues via improving electrodes, electrolytes, separators and binders. Remarkably, polymers can be readily applied to all these aspects due to their structural designability, functional versatility, superior chemical stability and processability. Moreover, their lightweight and rich resource characteristics enable the production of LSBs with high‐volume energy density at low cost. Surprisingly, there have been few reviews on development of polymers in LSBs. Herein, breakthroughs and future perspectives of emerging polymers in LSBs are scrutinized. Significant attention is centered on recent implementation of polymers in each component of LSBs with an emphasis on intrinsic mechanisms underlying their specific functions. The review offers a comprehensive overview of state‐of‐the‐art polymers for LSBs, provides in‐depth insights into addressing key challenges, and affords important resources for researchers working on electrochemical energy systems.

Layered nickel silicate provides massive interlayer space that is similar to graphite for the insertion and extraction of lithium ions and sodium ions; however, the poor electrical conductivity limits its electrochemical application in energy storage devices. Herein, carbon nanotube@layered nickel silicate (CNT@NiSiOx) coaxial nanocables with flexible nickel silicate nanosheets grown on conductive carbon 10 nanotubes (CNTs) are synthesized with a mild hydrothermal method. CNTs serve as the conductive cables to improve the electron transfer performance of nickel silicate nanosheets, resulting in reduced contact and charge-transfer resistances. In addition to high specific surface area, short ion diffusion distance and good electrical conductivity, the one-dimensional coaxial nanocables have a stable structure to sustain volume change and avoid structure destruction during the charge/discharge process. As an 15 anode material for lithium storage, the first cycle charge capacity of the CNT@NiSiOx nanocables reaches 770 mA h/g with the first cycle Coulombic efficiency as high as 71.5 %. Even after 50 cycles, the charge capacity still reaches 489 mA h/g at a current density of 50 mA/g, which is nearly 87 % and 360 % higher than those of NiSi/CNT mixture and nickel silicate nanotube, respectively. As anode material for sodium storage, the coaxial nanocables exhibit a high initial charge capacity of 576 mA h/g, which even 20 retains 213 mA h/g at 20 mA/g after 16 cycles. 65 By adjusting the amount of carbon precursor, the interlayer spacing could be altered between 1.22 to 3.37 nm, the specific capacity increased from 232 mA h/g for neat zinc silicate, to 455 mA h/g for zinc silicate/interlayer carbon composite, and further 85 bonded to CNT, CNT@NiSiOx nanocables exhibit good mechanical, thermal and cycling stability. The combination of NiSiOx and CNT shows good synergistic effect by increasing the lithium storage capacity and improving the electron and lithium ion diffusion efficiency of the nanocables. For lithium storage, 90 the charge capacity of CNT@NiSiOx after 50 cycles retains 489 TOC 5 Carbon nanotube@layered nickel silicate (CNT@NiSiOx) coaxial nanocables with flexible nickel silicate nanosheets grown on conductive carbon nanotubes (CNTs) are synthesized by a mild hydrothermal method. Massive interlayer space for lithium or sodium storage, improved electrical conductivity and C-O-Si 10 covalent bonding are benefit for structure stability during discharge/charge cycles and enhanced electrochemical property.

Fast diffusion rate of ions and sufficiently exposed active sites are important for catalysts. As a superior but rarely studied Fenton‐type catalyst, unsatisfactory ion diffusion rate of manganese silicate is the exact obstacle for improving its catalytic activity. Here, hierarchical manganese silicate hollow nanotubes (MnSNTs) assembled by tunable secondary structures are precisely fabricated by an efficient hydrothermal method and systematically investigated as Fenton‐type catalysts for the first time. The open end and thin mesoporous walls of the hollow nanotubes help shorten the diffusion pathway of ions and enhance the mass transport. Moreover, the numerous standing small nanosheets endow MnSNTs with higher specific surface area and larger pore volume than the large nanosheets and nanoparticles, and thus expose more active sites for adsorption and catalytic decomposition. MnSNTs are highly efficient in adsorption and catalytic decomposition of cationic dyes with an excellent recycling stability. About 98.1% of methylene blue is catalytically decomposed in 45 min at an ambient temperature of 25 °C. When the temperature increases to 60 °C, only 2 min are required, with a 530% higher kinetic constant than reported.