Nano Energy最新文献

Vanadium (V)-based glasses have recently garnered considerable attention as promising anode materials for lithium-ion batteries (LIBs) due to their abundance of Li⁺ storage sites, neglectable volume expansion upon lithiation/delithiation, and facile preparation. However, the inherently low electronic conductivity and relatively low energy density of V-based glass anodes hinder its application in full LIBs. In this work, we tackled this challenge by optimizing the chemical composition of the V-based glass anode to achieve high-performance half and full cells. We investigated the impact of partially substituting B₂O₃ for P₂O₅ in 50V₂O₅-(50-x)P₂O₅-xB₂O₃ (mol%) (VPB) glass series on its structure and electrochemical performances. The glass with 30 mol% B₂O₃ (VPB30 glass) was found to deliver the highest electronic conductivity, an enhanced reversible capacity of 470 mA h g⁻¹ at 1 A g⁻¹ after 500 cycles, and an excellent rate capability. The optimized performances were ascribed to the boosted lithium-ion diffusivity and the increased lithium storage sites. We assembled a full cell by coupling a VPB30 glass anode with a LiCoO₂ cathode to test its cycling performance. The VPB30//LiCoO₂ cell exhibits the required power density, and hence, high practicality. Our work implied the practical application of glass anodes in high-performance LIBs.

Two-dimensional (2D) materials have shown great potential in harvesting osmotic power due to their high membrane selectivity, but the high resistance from tortuous pathways of 2D nanofluidic membranes still impedes the further improvement in output performance. Here, we report an innovative 2D MXCT (MXene/Cu-TCPP) lamellar membrane with ultralow resistance for highly efficient osmotic power generation. The incorporation of 2D Ti₃C₂T_x MXene with rich functional groups not only resolves the water-stability issue of 2D metal-organic framework (MOF) Cu-TCPP, but provides large surface charges for selective ion transport. The orderly sub-2 nm framework channels of Cu-TCPP provide much shorter permeation pathways for fast ion transport, thus endowing the MXCT membrane with ultralow resistance. Consequently, the MXCT membrane reaches an ultrahigh power output of ∼8.29 W/m² by mixing seawater and river water, which is ∼275 % higher than that of the pristine MXene membrane. Additionally, it outperforms all the reported single-layer 2D nanosheet-based osmotic power generators under the same experimental conditions in terms of output power and internal resistance (9 kΩ). This work presents a reliable strategy for stabilizing 2D Cu-TCPP MOF in electrolytes, opening new avenues for designing promising 2D nanofluidic membranes for efficient blue energy harvesting and ionic devices.

FeOF as an intercalation-conversion cathode features a high theoretical capacity toward high energy density lithium-ion batteries (LIBs). However, the inadequate intercalation process and poor reversibility of redox reaction deteriorate its practical capacity and cycling stability. Herein, a S-substitution strategy in FeOF (FeOF-S) is proposed to boost the intercalation reaction and enhance the reaction kinetics, achieving a record-high capacity of 668 mAh g⁻¹ at 0.05 A g⁻¹ and a long cycling stability up to 1500 cycles at 0.5 A g⁻¹. Under this strategy, the Li⁺ intercalation energy of FeOF-S is remarkably reduced in thermodynamics, promoting the intercalation capacity to 230 mAh g⁻¹ which is 50% higher than that of FeOF. Furthermore, a nearly zero band gap with superior electronic conduction is achieved in FeOF-S, leading to excellent rate capability with much enhanced pseudo-capacitance contribution. This work presents new insights into the regulation of thermodynamics and kinetics toward the boosted electrochemical performance of conversion-type electrodes for high energy density LIBs.

Transparent conducting electrodes (TCEs) serve as essential components in various devices, including smart windows, thin film heaters, and sensors. Historically, indium tin oxide (ITO) thin films have served as the primary TCE material. However, the scarcity of indium in the Earth’s crust and costly vacuum-based deposition processes have prompted researchers to seek alternatives. While silver nanowire (Ag NW) networks have emerged as the leading candidate for TCEs among various alternatives, the presence of polyvinyl pyrrolidone (PVP) layer surrounding Ag NWs often leads to substantial contact resistances at the junction areas. Given the diverse characteristics of Ag NWs, including length, diameter, PVP thickness, and deposition methods, the efficacy of a specific post-treatment method on the same Ag NW batch remained unknown. This work collected effective post-treatment methods from existing literature and innovatively developed in-house approaches to optimize the treatment of Ag NW networks. Following post-treatment, the resulting electrodes exhibited a 70 % reduction in sheet resistance, with only a marginal 1 % decrease in optical transmittance. The optical figure of merit (FoM) for the optimized networks showed a remarkable five-fold improvement, rising from 66 to 305. The optimized Ag NW networks were then utilized as current collectors in water droplet-based TENG sensors, showcasing the device's effectiveness in pH and chemical concentration sensing. The fabricated TENG recorded peak Voc and Isc values of 22 V and 370 nA, respectively. Furthermore, we developed a sensor-integrated device capable of gauging the incident droplets’ pH level, signaling acid rain safety. In addition, the droplets activate a large-area Ag NW-based transparent thin film heater. Rapid defogging and defrosting capabilities of the heater was also demonstrated. The device holds the potential to be applied to the side-view mirrors of cars, providing an anti-fogging display for a significantly safer journey.

As an efficient mechanical energy harvester, the triboelectric-electromagnetic hybrid generator (TEHG) stands as a cornerstone in self-powered systems. Nevertheless, significant impedance disparities between triboelectric nanogenerators (TENGs) and electromagnetic generators (EMGs) often hamper systems’ energy utilization efficiency, attributed to impedance mismatch at the load. Here, a variable impedance strategy is proposed, aimed at maximizing the utilization of mechanical energies converted by TEHG. This approach capitalizes on electronic components with dynamic impedance from GΩ to kΩ in response to OFF-ON state transitions, thus matching the impedance of TENG and EMG. Experimentally, an ultraviolent gas discharge tube (UV-GDT) is integrated into the self-powered variable impedance system. Operated at 240 rpm, the TEHG-driven UV-GDT extracts energy amounting to 1304.27 mJ with an 87.5 % utilization efficiency. These metrics outperform the situation where UV-GDT is individually powered by either EMG (0 mJ, 0 %) or TENG (18.24 mJ, 60.7 %). Furthermore, the mechanical energy-activated UV system demonstrates promise for sterilization, curing, and photo-chemical reactions. This variable impedance strategy resolves the impendence mismatch between TEHG and load, more importantly, provides a valuable guideline for developing hybrid generator systems with enhanced energy utilization efficiency.

Self-propelled soft robots have attracted extensive attention because of their unique application in exploring dangerous and complex environments that are unsuitable for human beings. However, these soft robots require cyclical chemical stimulation or external power and have short locomotion times, which limits their practical applications. It remains challenging to create self-propelled soft robots exhibiting long-term locomotion. Here, we couple an active hydrogel with a solar absorbing coating to realize self-propelled soft robots with long-term locomotion. The active hydrogel can move freely on the water surface by continuously establishing asymmetric surface tension through dynamic wetting. The sunlight absorbers promote water evaporation inside the self-propelled soft robot to delay or even disrupt the swelling equilibrium of the hydrogel, thus establishing dynamic balance between water absorption and evaporation. In this way, the locomotion time of this self-propelled soft robot under constant light irradiation equivalent to 1 sun (1 kW/m²) is 6.5 times higher than that of active hydrogel reported previously. Owing to the enhanced locomotion time through solar water evaporation water, this self-propelled soft robot is expected to be applied to oil pollution exploration, cargo transportation, and debris cleaning in small water areas.

Seawater electrolysis is a promising technique for H₂ production on a large scale. However, the electrocatalytic activity and stability will be deteriorated as the increase of salt concentrations which happened in the seawater splitting. Herein, through the electrodeposition and rapid Joule heating method, the Fe-NiO/MoO₂ heterostructure is designed as a highly active bifunctional electrocatalyst. During the OER possess, Fe-NiO/MoO₂ is reconstructed to the Fe, Mo-NiOOH with Fe and Mo co-doping. Based on the theoretical analysis, more electrons were transferred to the O atoms on the surface of Fe, Mo-NiOOH, thereby forming a more negatively charged surface. Moreover, that surface is found to repel Cl⁻ ions while enriching H₂O molecules to form a thin water layer on Fe, Mo-NiOOH surface based on molecule dynamics (MD) simulation, thereby improving the anti-corrosion capacity of Fe, Mo-NiOOH. The reconstructed Fe, Mo-NiOOH achieved an overpotential of 399 mV at 1000 mA cm⁻² in alkaline seawater, and the increase of overpotential for Fe, Mo-NiOOH was about 0.02 V at 500 mA cm⁻² from 0 M to 3 M NaCl in 1 M KOH electrolyte. For the HER, Fe-NiO/MoO₂ achieved an overpotential of 169 mV and 417 mV at 100 and 1000 mA cm⁻² in alkaline seawater, respectively, and the increase of overpotential for Fe-NiO/MoO₂ was about 0 mV at 500 mA cm⁻² from 0 M to 3 M NaCl in 1 M KOH electrolyte. This work sheds fresh light into the development of efficient electrocatalysts for salinity tolerance seawater splitting.

Triboelectric nanogenerators (TENGs) have been widely used in energy harvesting from low-frequency, irregular motions due to their unique characteristics and excellent electromechanical conversion efficiency. Harvesting ocean energy to build a marine Internet of Things (MIoTs) has become an important research field for TENGs. However, the output power density of TENGs must be further enhanced for promoting their practical applications, by effective means such as the coupling of TENGs and electromagnetic generators (EMGs). Herein, we report a triboelectric-electromagnetic hybrid nanogenerator (TEH-NG) for self-powered ocean buoy to harvest water wave energy efficiently for the first time. The buoy consists of a self-engineered wave energy converter for converting wave energy into simple turbomachinery energy through the pressure difference created by the relative motion, and a TEH-NG for converting the turbomachinery energy into electrical energy. The TENG delivers an average output power of 3.40 mW (with power density of 141.7 W m⁻³), and the EMG achieves an average power of 0.04 W (with power density of 400.0 W m⁻³). The excellent performance of the TEH-NG makes it a potential candidate for constructing the MIoTs to achieve distributed marine environmental monitoring networks.

P2-type cathode has received extensive attention due to its faster Na⁺ diffusion and a high theoretical capacity in sodium-ion batteries (SIBs). However, undesirable phase transformations have induced dramatic capacity decay of SIBs during the cycling process. In this study, heteroatom anchoring through Cu/Mg dual doping is introduced into P2-type Na_0.67Ni_0.33Mn_0.67O₂ cathode to enhance high-voltage electrochemical reversibility and modulate interfacial Na⁺ kinetics. The as-prepared Na_0.67Ni_0.23Mg_0.05Cu_0.05Mn_0.67O₂ exhibits an outstanding capacity retention (83.4 % after 2000 cycles at 10 C) and rate performance (73 mAh g⁻¹ at 10 C, accounting for 58.7 % of that at 0.1 C) over the voltage range of 2.5–4.4 V. Intensive explorations further manifest that the modified mechanism of dual-ion doping strategy is attributed to the synergistic coupling effect of a substantial change in Na occupancy distribution and an increase in oxygen vacancy buffer. Thus, the optimized cathode expedites Na⁺ diffusion and reduces detrimental phase transformation, which favors high-rate performance and long-term cycling stability. This study develops a route to rationally design high-voltage cathode materials for SIBs.