One‐dimensional Si nanostructures with carbon coating (1D Si@C) show great potential in lithium ion batteries (LIBs) due to small volume expansion and efficient electron transport. However, 1D Si@C anode with large area capacity still suffers from limited cycling stability. Herein, a novel branched Si architecture is fabricated through laser processing and dealloying. The branched Si, composed of both primary and interspaced secondary dendrites with diameters under 100 nm, leads to improved area capacity and cycling stability. By coating a carbon layer, the branched Si@C anode shows gravimetric capacity of 3059 mAh g−1 (1.14 mAh cm−2). At a higher rate of 3 C, the capacity is 813 mAh g−1, which retained 759 mAh g−1 after 1000 cycles at 1 C. The area capacity is further improved to 1.93 mAh cm−2 and remained over 92% after 100 cycles with a mass loading of 0.78 mg cm−2. Furthermore, the full‐cell configuration exhibits energy density of 405 Wh kg−1 and capacity retention of 91% after 200 cycles. The present study demonstrates that laser‐produced dendritic microstructure plays a critical role in the fabrication of the branched Si and the proposed method provides new insights into the fabrication of Si nanostructures with facility and efficiency.

Si has been extensively investigated as an anode material for lithium-ion batteries because of its superior theoretical capacity. However, a scalable fabrication method for a Si-based anode with high initial coulombic efficiency (ICE) and large volumetric capacity remains a critical challenge. Herein, we proposed a novel porous Si/Cu anode in which planar Si islands were embedded in the porous Cu matrix through combined laser additive manufacturing and chemical dealloying. The compositions and dimensions of the structure were controlled by metallurgical and chemical reactions during comprehensive interaction. Such a structure has the advantages of micro-sized Si and porous architecture. The planar Si islands decreased the surface area and thus increased ICE. The porous Cu matrix, which acted as both an adhesive-free binder and a conductive network, provided enough access for electrolyte and accommodated volume expansion. The anode structure was well maintained without observable mechanical damage after cycling, demonstrating the high structure stability and integrity. The porous Si/Cu anode showed a high ICE of 93.4% and an initial volumetric capacity of 2131 mAh cm–3, which retained 1697 mAh cm–3 after 100 cycles at 0.20 mA cm–2. Furthermore, the full-cell configuration (porous Si/Cu //LiFePO4) exhibited a high energy density of 464.9 Wh kg–1 and a capacity retention of 84.2% after 100 cycles.

A series of high-strength and highly microporous phenolic open-cell foams modified by different epoxy resins were fabricated using physical foaming method. The new compound emulsifiers consisting of anionic and nonionic surfactants were physical blended at high speed with modified resols, foaming agent, and mixed acid curing agent. The modified synthesis of epoxy-modified phenol-formaldehyde (PF) resin was conducted via the etherification mechanism. In order to verify the occurrence of etherification mechanism by co-reaction between resole methylol, hydroxyl group, and ring-opening epoxy group and to characterize the structure successfully, Fourier transform infrared spectroscopy, carbon-13 (13C) and proton nuclear magnetic resonance (1H NMR) had been used to characterize the structure successfully. The phase of resols and curing behavior were characterized. Fabricated foams were characterized for cellular, water absorption, apparent density, and mechanical and thermal properties. The results show epoxy modified resol demonstrated single uniform phase. The open-cell micropore structure revealed by scanning electron microscopy (SEM) demonstrates that smaller and more homogeneous cells existed with increasing dosage of epoxy. When the content of epoxy increased from 0 wt% to 10 wt%, the thermal conductivity, water absorption, and porosity of PF gradually increased. The highest open-cell porosity reached up to 90.959%. The differential scanning calorimetry and gel time data demonstrated that modified resols exhibited less gel time and lower endothermic and curing exothermic heat. Anionic surfactant, sodium dodecyl sulfonate, which was better compatible with resol, promoted the formation of open cells and produced good homogeneous and moderate micropores. In addition, the high-strength open-cell PF possessed excellent filterable and separation performance and absorbency. The porous micropore structure controlled by the content of epoxy resin and the ratio of sodium dodecyl sulfate /Tween80 greatly improved the mechanical strengths of PF.

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In this paper, 3D-Mn/MnO x periodic arrays architecture is fabricated through a facile and efficient method. A femtosecond laser is used to generate a 3D conductive network on a metallic manganese surface which also serves as the current collector (3D-Mn), followed by chemical oxidation to form Mn2O3 and MnO2 on the surface of the 3D-Mn. Detailed electrochemical characterization reveals that the 3D-Mn/MnO x electrode exhibits good rate performance and cycle life, and the assembled 3D-Mn/MnO x supercapacitor can deliver the highest energy density of 5.6 μWh/cm2 at a power density of 21.8 μW/cm2. The enhanced performance is attributed to the unique periodic 3D-Mn/MnO x architecture which largely increases the effective electrode surface area, shortens the electron/ion transportation distance, facilitates electrolyte permeation, and reduces the contact resistance between 3D-Mn and MnO x . Importantly, MnO x is formed directly on the 3D-Mn surface, which helps to maintain the structural integrity and mechanical adhesion between each other, and thus is beneficial to long-term electrochemical cycling.