High-performance and novel graphene-based electrothermal films are fabricated through a simple yet versatile solution process. Their electrothermal performances are studied in terms of applied voltage, heating rate, and input power density. The electrothermal films annealed at high temperature show high transmittance and display good heating performance. For example, the graphene-based film annealed at 800 °C, which shows transmittance of over 80% at 550 nm, can reach a saturated temperature of up to 42 °C when 60 V is applied for 2 min. Graphene-based films annealed at 900 and 1000 °C can exhibit high steady-state temperatures of 150 and 206 °C under an applied voltage of 60 V with a maximum heating rate of over 7 °C s(-1) . For flexible heating films patterned on polyimide, a steady-state temperature of 72 °C could be reached in less than 10 s with a maximum heating rate exceeding 16 °C s(-1) at 60 V. These excellent results, combined with the high chemical stability and mechanical flexibility of graphene, indicate that graphene-based electrothermal elements hold great promise for many practical applications, such as defrosting and antifogging devices.

Although lithium (Li)-ion batteries have achieved great success in commercialization for sustainable and clean energy applications including portable electronics, electric transportation, and grid-scale energy storage, existing battery systems of graphitebased anodes and transition metal oxide-based cathodes hardly meet the increasing requirements for higher energy and power densities. [1][2][3][4] Li metal has a high theoretical capacity Metallic lithium (Li) is a promising anode for next-generation high-energydensity batteries, but its applications are still hampered due to the limited charging/discharging rate and poor cycling performance. Here, a hierarchical 3D porous architecture is designed with a binary network of continuous silver nanowires assembled on an interconnected 3D graphene skeleton as the host for Li-metal composite anodes, which offers a significant boost in both charging/discharging rates and long-term cycling performance for Li-metal batteries. This unique hierarchical binary network structure in conjunction with optimized material combination provides ultrafast, continuous, and smooth electron transportation channel and non-nucleation barrier sites to direct and confine Li deposition. It also offers outstanding mechanical strength and toughness to support massive Li deposition and buffer the internal stress fluctuations during long-term repeated Li stripping/plating thereby minimizing fundamental issues of dendrite formation and volume change even under ultrafast charging/discharging rates. As a result, the composite anode using this hierarchical host can work smoothly at an unprecedented high current density of 40 mA cm -2 over 1000 plating/stripping cycles with low overpotential (<120 mV) in symmetric cells. The as-constructed full cell, paired with LiNi 0.5 Co 0.2 Mn 0.3 O 2 cathode, also exhibits excellent rate capability and high-rate cycling stability.(3860 mAh g −1 ) and low electrochemical potential (−3.04 V vs the standard hydrogen electrode) and is thus perceived as an ideal anode for next-generation rechargeable batteries-especially for Li-sulfur and Li-oxygen battery systems. [5][6][7][8] However, the use of a Li-metal anode in advanced battery systems for stable and ultrafast charging/discharging is severely restricted by safety and cyclability concerns caused by dendritic Li formation, infinite volume change, and instability of solid electrolyte interphase (SEI). This has limited the practical use of Li-metal batteries for many decades. [9][10][11][12][13] Several strategies focused on constructing stable and uniform SEI layer on Li anode have been explored to tolerate the huge volume change and suppress the formation of dendritic Li. Examples include optimizing the electrolyte contents, modifying he Li anode surface, and developing artificial coatings on the anode surface. [10,[13][14][15][16] Despite the great success achieved on the rational design of SEI layer, the nature of Li dendrite formation arising from inhomogeneous Li-ion flux distribution on planar Li foil or copp...

Exceptionally high specific surface area, mechanical strength, electrical conductivity, and a special two‐dimensional structure make graphene a highly promising material for electromechanical actuators. Electromechanical actuators are fabricated using flexible graphene‐based paper prepared via a filtration process, and the stroke of these graphene‐based actuators is directly measured during electrochemical double‐layer charge injection. Actuation strain up to 0.064% was obtained for pristine graphene paper in response to an applied potential of –1 V in 1 M NaCl solution. Double‐layer charge injection in graphene sheets is believed to induce actuation strain through a combination of coulombic and quantum‐chemical‐based expansion. To increase electrochemical‐double‐layer capacitance and actuator performance, Fe3O4 nanoparticles were used to partially prevent graphene sheets from restacking and allow the electrolyte ions to infiltrate the resulting magnetic graphene paper more easily. The magnetic graphene paper exhibits actuation strain as large as 0.1% at –1 V applied potential, which is about 56% higher than that of the pristine graphene paper.

The emerging field of free-standing and flexible paperlike materials based on graphene sheets has become the focus of considerable research in recent years because of the scientific and technological significance of these materials. In particular, multifunctional flexible graphene-based films or papers are in high demand for various applications. Herein, we report the fabrication of magnetic, electrically conducting, and flexible paper composed of graphene and nanoscale Fe3O4 particles made using a simple yet versatile solution-processed approach. The conductive, magnetic, and mechanical properties of these free-standing hybrid papers with different loadings of nanoscale Fe3O4 particles were investigated. In addition to the excellent electrical conductivity and mechanical strength, the obtained flexible graphene/Fe3O4 hybrid papers also show superparamagnetism, which can be tuned easily through modulation of the loading of Fe3O4 nanoparticles. Combining all of these outstanding properties, we have fabricated and demonstrated a magnetic-controlled conductive switch using these flexible and multifunctional graphene/Fe3O4 hybrid papers.

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