Vanadium redox flow batteries (VRFBs) are widely applied in energy storage systems (e.g., wind energy, solar energy), while the poor activity of commonly used carbon-based electrode limits their large-scale application. In this study, the graphene modified carbon felt (G/CF) with a large area of 20 cm ׁ 20 cm has been successfully prepared by a chemical vapor deposition (CVD) strategy, achieving outstanding electrocatalytic redox reversibility of the VRFBs. The decorating graphene can provide abundant active sites for the vanadium redox reactions. Compared with the pristine carbon felt (CF) electrode, the G/CF composite electrode possesses more defective sites on surface, which enhances activity toward VO²⁺/VO₂⁺ couple and electrochemical performances. For instance, such G/CF electrode delivered remarkable voltage efficiency (VE) of 88.4% and energy efficiency (EE) of 86.4% at 100 mAdcm^-2, much higher than CF electrode by 2.1% and 3.78%, respectively. The long-term cycling stability of G/CF electrode was further investigated and a high retention value of 47.6% can be achieved over 600 cycles. It is demonstrated that this work develops a promising and effective strategy to synthesize the large size of carbon electrode with high performances for the next-generation VRFBs.

Silicon (Si) is regarded as a promising anode material for next-generation lithium-ion batteries due to its ultrahigh theoretical capacity. However, the drastic volume change and the continuous solid electrolyte interphase (SEI) formation during the lithiation/delithiation process seriously hinder its practical application as commercial anodes. Herein, macrocyclic beta-cyclodextrin (β-CD) has been designed as the diffusion channel for lithium ions at the molecular scale. The diameter of molecular channel is approximately comparable with the solvated lithium ions, which enables the transport of lithium ions and prevents the penetration of solvent molecules. Moreover, the addition of β-CD changes the formation behavior of SEI layer and stabilizes the Si nanoparticles. The enhanced electrochemical performances in terms of fast kinetics and improved stability have been achieved. The Si anode with the particularly selected lithium-ion diffusion channel and stabilized SEI layer exhibits a high reversible capability of 2 562 mAh g⁻¹ after 50 cycles at the current density of 500 mA g⁻¹, 1 944 mAh g⁻¹ after 200 cycles at the current density of 1 A g⁻¹, and high rate performance. The novel strategy of molecular channel for lithium-ion diffusion offers new insights into the design of alloy-typed anode electrodes with high capacity for lithium-ion batteries.

Traditional synthetic methodologies are confronted with great challenges to fabricate complex nanomaterials with delicate design, high efficiency and excellent sustainability. During the past decade, bio-inspired synthesis has been extensively applied as an effective and efficient strategy for the fabrication of nanomaterials and nanostructures. Mimicking electrode materials at nanoscale in the aspect of either structure or functionality has been receiving surging interest because of their incomparable advantages and outperforming properties. In this review, we summarize the recent progresses on bio-inspired synthesis of nanomaterials and smart structures in the field of energy storage and conversion. Firstly, an overall introduction of bio-inspired synthetic strategies will be presented, with focus on the bio-templates and bio-resources. Following that, a library of complex mimicking structures featured by high-order, hierarchical porosity, or bionic function are introduced, with discussion on their chemical and physical properties associated with the structure. The enhanced electrochemical properties such as energy density, cycling stability, etc. in different electrochemical systems will be also discussed. At last, we will expand the perspectives regarding the advantages and limitations of bio-inspired strategy and possible solutions in the future.