Field effect nanogenerator operated by sliding gates

Chemical Engineering Journal

As wearable devices in the fields of medical health, human–computer interaction, and motion detection continue to diversify in their materials and forms, they show vast application potential. Cellulose materials are emerging as prominent materials for fabricating flexible wearable electronic devices because of their favorable skin compatibility, cost-effectiveness, and abundance. However, there is little research on the use of kapok cellulose in wearable electronics. This study addresses this knowledge gap by exploring the high-yield production and waste recycling potential of kapok cellulose. To overcome the limitations of conventional cellulose films, such as poor flexibility, high haze, and limited light transmittance, a kapok cellulose nanofiber film (KCNF) with a transparency of > 90 % and a tensile strain of > 20 % is prepared. The use of of KCNF as a friction electric material in the triboelectric nanogenerator …

Advanced Materials

Triboelectric nanogenerators offer an environmentally friendly approach to harvesting energy from mechanical excitations. This capability has made them widely sought‐after as an efficient, renewable, and sustainable energy source, with the potential to decrease reliance on traditional fossil fuels. However, developing triboelectric nanogenerators with specific output remains a challenge mainly due to the uncertainties associated with their complex designs for real‐life applications. Artificial intelligence‐enabled inverse design is a powerful tool to realize performance‐oriented triboelectric nanogenerators. This is an emerging scientific direction that can address the concerns about the design and optimization of triboelectric nanogenerators leading to a next generation nanogenerator systems. This perspective paper aims at reviewing the principal analysis of triboelectricity, summarizing the current challenges of …

The growing popularity of the Internet of Things has led to increases in the need for renewable energy and sensor systems. Therefore, triboelectric nanogenerators (TENGs) have garnered significant attention as a novel form of energy production due to their lightweight nature, cost-effectiveness, high output, and versatility in terms of materials, low cost, and device configurations. TENGs have been studied for several uses, including self-powered sensing, biomedical, biomotion, healthcare monitoring, and robotic applications. The performance of TENG is drastically pretentious by the material because charge density (σ) is an inherent characteristic of the material. Metal-organic framework (MOF) materials possess robust charge-trapping capabilities, multifunctional structures, adjustable properties, and exceptional stability. These materials can be utilized or integrated as self-powered sensors of different kinds to …

Advanced Materials Technologies

Although natural evaporation absorbs substantial thermal energy from the ambient environment, efficiently utilizing this high‐entropy energy remains challenging. Here, the first water evaporation‐induced triboelectric nanogenerator is proposed. It only uses tap water to harvest low‐grade heat energy from the surroundings to convert it into electricity. The natural evaporation of the liquid can generate unintermittent electricity with an open‐circuit voltage of 382 V, a peak power of 0.42 mW, and three orders of magnitude enhancement up to 59.7 mJ mL−1 after consuming the same amount of tap water compared with the droplet‐based electricity generators. After which, the excellent power output lights 2 W LED and drives wearable electronic devices. This device also inhibits carbon steel materials' corrosion in solutions through the evaporation effect of the salt water on the spot. The present study provides novel …

Nano Energy

Tactile perception systems as the medium between the ambient environment and robotics lie in the heart of modern artificial intelligence. By providing different electronic readouts under various circumstances, they can give easily captured information for post-processing. However, for applications of most reported tactile perception systems, external location assistances are still needed. Here, as inspired by the platypus’ sixth sense, we developed a new kind of tactile perception system based on triboelectric sensors with the additional function from quantum rods. This terminal can be used as a single-electrode mode triboelectric nanogenerator for both location detection and vertical force sensing with high sensitivity and fast response. Moreover, by adding CdSe/CdS quantum rods into an imprinted polydimethylsiloxane film, different lateral stretching levels can be perceived by a modified luminescence. Supported …

Energy & Environmental Science

Controlling the motion of charge carriers in semiconductor materials is a fundamental strategy for achieving many functional devices, which is typically achieved by applying an external voltage source. Herein, using the electrostatic potential generated by a triboelectric material taken as a sliding “gate”, a functional current is generated across a semiconductor channel when the gate is moving in parallel to the dielectric surface. Systematic studies verify that the motion of the electrified “gate” induces the regional and dynamical doping of the semiconductor channel, thereby driving the carrier transport without applying an external voltage. This sliding-gated generator achieves mechanoelectric energy conversion based on the coupled triboelectrification effect and electrostatic field effect and is therefore termed as a field effect nanogenerator (FENG). It can output electrical currents with a waveform that follows well with …

Advanced Materials Technologies

Wearable and implantable triboelectric nanogenerators (TENGs) convert mechanical energy to electricity in the daily movements of the human body. Self‐generated dynamic electric field or displacement current of TENGs can operate from micrometers to centimeters, which offers a key technology for TENG‐based therapy systems for precision medicine on both tissues and cells. TENGs have low‐current and high‐voltage properties, which reduce damage to normal tissues, and kill rapidly dividing cancer cells. In this work, the dynamic electric field from TENG directly inhibits the cellular proliferation behavior of cancer cells. The work paves a new way for the self‐generated electric field of TENG for cancer therapy.

Journal of Power Sources

High-frequency supercapacitors (HF–SCs) are promising electric energy storage devices and alternating current line filters. However, severe self-discharge of HF–SCs causes significant energy loss and limits their applications. Current self-discharge suppression methods for supercapacitors typically lead to decreased rate performance and hence cannot be applied to HF–SCs directly. In this work, barium titanate (BTO) nanoparticles are employed as an electrolyte additive for HF–SCs to reduce self-discharge. By adding BTO nanoparticles into the electrolyte, both leakage current and decay of open circuit voltage of the devices are reduced without sacrificing the specific capacitance and high-frequency response. At a charging voltage of 2 V, the leakage current is reduced by 49 % (3.91 vs. 1.98 μA), while the time for the voltage to drop from 2.0 to 1.0 V is extended by 4.5 times (2300 vs. 10240 sec). When the HF …

Advanced Materials

Recently, perovskite photodetectors (PDs) have been risen to prominence due to substantial research interest. Beyond merely tweaking the composition of materials, a cutting‐edge advancement lies in leveraging the innate piezoelectric polarization properties of perovskites themselves. Here, the investigation shows utilizing Ti3C2Tx, a typical MXene, as an intermediate layer for significantly boosting the piezoelectric property of MAPbI3 thin films. This improvement is primarily attributed to the enhanced polarization of the methylammonium (MA+) groups within MAPbI3, induced by the OH groups present in Ti3C2Tx. A flexible PD based on the MAPbI3/MXene heterostructure was then fabricated. The new device is sensitive to a wide range of wavelengths, displays greatly enhanced performances owing to the piezo‐phototronic coupling. Moreover, the device is endowed with a greatly reduced response time, down …

Energy & Environmental Science

Establishing maintenance-free wireless sensor networks for online monitoring of power transmission lines is crucial for realizing smart grids, exhibiting necessitating energy harvesters with compact volume, excellent robustness, and efficient, well-regulated output. This study introduces a hybrid magnetic energy harvester (HMEH), seamlessly integrating a magneto-mechanical energy conversion module, a non-contact rotational triboelectric nanogenerator (TENG) module, and an electro-magnetic generator (EMG) module for magnetic energy harvesting and self-powered sensing in power transmission lines. The HMEH converts magnetic energy into synchronized mechanical rotation using the magnetic phase difference principle and smoothly transforms it into a regulated electrical energy output. With a compact size of 5 cm × 5 cm × 3 cm and a light weight of 56 g, the HMEH showcases unprecedented volume and …

Small

Triboelectric nanogenerator (TENG) is a promising solution to harvest the low‐frequency, low‐actuation‐force, and high‐entropy droplet energy. Conventional attempts mainly focus on maximizing electrostatic energy harvest on the liquid‐solid surface, but enormous kinetic energy of droplet hitting the substrate is directly dissipated, limiting the output performance. Here, a dual‐mode TENG (DM‐TENG) is proposed to efficiently harvest both electrostatic energy at liquid‐solid surface from a droplet TENG (D‐TENG) and elastic potential energy of the vibrated cantilever from a contact‐separation TENG (CS‐TENG). Triggered by small droplets, the flexible cantilever beam, rather than conventional stiff ones, can easily vibrate multiple times with large amplitude, enabling frequency multiplication of CS‐TENG and producing amplified output charges. Combining with the top electrode design to sufficiently utilize charges at …

ACS Applied Materials & Interfaces

The global annual vegetable and fruit waste accounts for more than one-fifth of food waste, mainly due to deterioration. In addition, agricultural product spoilage can produce foodborne illnesses and threaten public health. Eco-friendly preservation technologies for extending the shelf life of agricultural products are of great significance to socio-economic development. Here, we report a dual-functional TENG (DF-TENG) that can simultaneously prolong the storage period of vegetables and realize wireless storage condition monitoring by harvesting the rotational energy. Under the illumination of the self-powered high-voltage electric field, the deterioration of vegetables can be effectively slowed down. It can not only decrease the respiration rate and weight loss of pakchoi but also increase the chlorophyll levels (∼33.1%) and superoxide dismutase activity (∼11.1%) after preservation for 4 days. Meanwhile, by …

Nature Communications

Harvesting biomechanical energy from cardiac motion is an attractive power source for implantable bioelectronic devices. Here, we report a battery-free, transcatheter, self-powered intracardiac pacemaker based on the coupled effect of triboelectrification and electrostatic induction for the treatment of arrhythmia in large animal models. We show that the capsule-shaped device (1.75 g, 1.52 cc) can be integrated with a delivery catheter for implanting in the right ventricle of a swine through the intravenous route, which effectively converts cardiac motion energy to electricity and maintains endocardial pacing function during the three-week follow-up period. We measure in vivo open circuit voltage and short circuit current of the self-powered intracardiac pacemaker of about 6.0 V and 0.2 μA, respectively. This approach exhibits up-to-date progress in self-powered medical devices and it may overcome the inherent …

Advanced Materials

Although dielectric elastomer actuators (DEAs) are promising artificial muscles for use as visual prostheses in patients with oculomotor nerve palsy (ONP), high driving voltage coupled with vulnerable compliant electrodes limits their safe long‐term service. Herein, a self‐healable polydimethylsiloxane compliant electrode based on reversible imine bonds and hydrogen bonds is prepared and coated on an acrylic ester film to develop a self‐healable DEA (SDEA), followed by actuation with a high‐output triboelectric nanogenerator (TENG) to construct a self‐powered DEA (TENG‐SDEA). Under 135.9 kV mm−1, the SDEA exhibits an elevated actuated strain of 50.6%, comparable to the actuation under DC power. Moreover, the mechanically damaged TENG‐SDEA displays a self‐healing efficiency of over 90% for 10 cycles. The TENG ensures the safe using of TENG‐SDEAs and an extraocular‐muscle‐like actuator …

Chemical Engineering Journal

Triboelectric nanogenerators (TENGs) and lithium-ion batteries (LIBs) play an important role in the field of clean energy as energy conversion and storage devices respectively. It is vital to fabricate efficient transport between TENGs and LIBs for promoting the development in combined energy systems. This work constructs an efficient energy transport system between the contact-energy contact-separation TENG (CCS-TENG) and the LIB by introducing power management based on a short-circuit contact in-situ. Such synergy system satisfies the needs of improving the efficient connection between TENGs and LIBs, durability and miniaturization of energy unit. The short-circuit contact in-situ guarantees the maximum energy output of CSS-TENG in every contact-separation cycle and the energy density is as high as 131.1 mJ m−2 cycle−1, although the electrode of CCS-TENG is only 10 cm2. Moreover, the TENG cycle …

Advanced Functional Materials

The utilization of unmanned aerial vehicles (UAVs) is on the rise across various industries. In such a scenario, the issue of flight safety for these UAVs becomes increasingly paramount. Currently, UAVs exhibit shortcomings in flight attitude perception compared to more mature manned aircraft, especially concerning the position sensing of flight actuation, which poses significant safety risks. Mature position monitoring solutions for flight actuation used in manned aircraft cannot be directly integrated into systems of UAV due to compatibility issues. This necessitates the development of new position sensing technologies to address this challenge. Triboelectric nanogenerators, with their advantages of miniaturization, self‐powering capabilities, and the ability to generate voltage‐level electrical signals, are chosen to form a part of the position detection system for sensors in UAVs. In this study, a self‐powered …

As one of the few self-powered instruments and devices, triboelectric nanogenerators (TENGs) have been developed for more than 10 years since its invention in 2012. With wide material selections and diverse design structures, and without having to use an external power supply, TENG has been applied in many key technologies. By the end of 2022, more than 16,000 researchers from 83 countries and regions around the world have authored scientific papers in TENG. In this review, we start from the theoretical principles and working mechanisms of TENG, and discuss its 5 major fields of application, namely, as self-powered sensors, high-voltage energy devices, blue energy devices, micro/nano-energy devices, and solid–liquid interface probes. Next, we review the breakthrough progress made using TENG as commercial products in the following fields: medical health, intelligent security, and marine energy …

Nano Energy

While triboelectric nanogenerated knitted fabrics are regarded as a state-of-the-art and reliable energy source for wearable electronics, there are two bottlenecks in their widespread applications: few mass-manufacturing strategies and low power output. Here, by mature weft-knitted technologies, a 3D single-faced jacquard pile fabric TENG (SJPF-TENG) with the merits of high surface pile density, excellent comfort and breathability, good thermal insulation property, and superior durability, is mass-produced. Based on the high-density pile structure (about 16128 piles per cm2), the surface area of pile fabrics is 42.2 times that of the plain structure, which endows the SJPF-TENG with higher electrical outputs and good detection precision. With a peak power density of 1.4 W m−2 (dozens of times that of conventional textile-based TENGs), the SJPF-TENG is capable of lighting up 1392 light-emitting diodes, powering …

Energy & Environmental Science

The photocatalytic overall water splitting reaction provides a pathway to hydrogen fuel from sunlight. Photocatalysts must achieve the reaction without the application of an external bias, which requires an effective charge separation mechanism. Photolabeling studies and electrostatic simulations for the well-known CoOOH/Al:SrTiO3/Rh/Cr2O3 photocatalyst suggest that charge separation is driven by work function differences at the (100) and (110) facets of SrTiO3, which are electron and hole selective, respectively. Here we use hydrogen annealed SrTiO3−x single crystals to obtain the first quantitative assessment of the charge separation ability of the (100), or (110), or (111) facets during oxygen evolution. Under UV illumination (60 mW cm−2), the crystals exhibit variable water oxidation photocurrents (0.34, 0.82, 1.36 mA cm−2 at 1.23 V versus RHE) and photovoltage values of 1.40, 1.52 and 1.52 V for (100), (110 …

Energy & Environmental Science

Alkaline-based aqueous batteries have attracted intensive research interests due to their high voltage, low cost, and high safety. However, metal anodes in alkaline electrolytes usually possess poor stability and severe side reactions. Organics are potential alternatives to address these problems, but they are typically not negative enough as anodes. Herein, a group of organic phenazine derivatives including phenazine (PZ), 2-hydroxyphenazine (PZ-OH), and 1,2-dihydroxyphenazine (PZ-2OH) are developed as anode materials for alkaline-based batteries. It is revealed that introducing hydroxyl groups can lower the redox potential by 0.4 V, and fast ion transport channels formed by intramolecular hydrogen bonds can remarkably improve redox kinetics. The optimized PZ-2OH‖Ni (OH)2 batteries deliver a high capacity of 208 mA h g−1anode, a high energy density of 247 W h kg−1anode, and ultra-stable cyclability …

Energy & Environmental Science

Organic solar cells (OSCs) based on oligomer acceptors have garnered significant interest for their notable power conversion efficiency (PCE) and enduring stability. Despite their great potential, the development of oligomer acceptors remains behind traditional small molecule acceptors (SMA) -based systems, primarily due to a scarcity of effective oligomer materials. To address this gap, our study introduces a novel hybrid synthesis strategy for oligomer acceptors, integrating two distinct acceptor units. We synthesize the heterotrimer acceptor TQT and the single-acceptor-unit oligomers Tri-BT and Tri-Qx to assess the impact of our approach on OSC performance and durability. Notably, the crystallinity of the hybrid molecule TQT is significantly enhanced compared to the other two molecules. Consequently, the PCE of the PM6:TQT OSC reached 18.52%, marking the highest efficiency observed in OSCs composed of …

Energy & Environmental Science

Zn powder with large-scale production and well-tunability is promising for aqueous Zn-ion batteries, but its extremely short lifespan seriously hinders the practical application. Herein, we disclose that Zn powder anode failure is majorly caused by top-down plating and bottom-up stripping behaviors, and accordingly develop an iso-plating/stripping strategy to achieve an ultra-long lifetime practical Zn powder anode. The zincophilic Bi-metal nanosheets are anchored on the Zn powder surface, which could serve as preferred Zn nucleation sites and charge-aggregated protrusions, endowing homogeneous plating/stripping and gradient-free Zn2+ distribution throughout the powder electrode. Furthermore, the Bi has additional advantages including guiding Zn (002)-orientated growth and suppressing side reactions for further structural stability, permitting unprecedented stable cycling of over 5600 h at 1 mA cm-2 and …

Energy & Environmental Science

The world’s first demonstration of passive radiative cooling under the sun in 2014 attracted substantial attention due to its ubiquitous and passive nature. Numerous nanophotonic and metamaterials capable of radiative sky cooling have been reported over the past decade. However, the cooling power density of such materials is approximately one magnitude lower (100 W m-2) compared to terrestrial solar irradiation. Furthermore, improved optical characteristics could yield a modest increase in cooling power density due to the blackbody radiation limit. We report a rationally designed AsymSkyCool method (Asymmetrically-sized heat-source-on-radiative-Sky-Cooling-coated-substrate) for radiative sky cooling thermal concentration (tcRC). The tcRC concept yields over 2000 W m-2 at night and close to 1000 W m-2 at 493 W m-2 solar irradiation. The nearly tenfold improvement over the state-of-the-art sky cooling …

Energy & Environmental Science

Enabling green-solvent-processed large-area organic solar cells (OSCs) is of great significance to their industrialization. However, precisely controlling the temperature-dependent fluid mechanics and evaporation behavior of green solvents with high-boiling points is challenging. Controlling these parameters is essential to prevent the non-uniform distribution of active layer components and severe molecule aggregation, which collectively degrade the power conversion efficiency (PCE) of large-scale devices. In this study, we revealed that the temperature gradient distribution across a wet film is the root of the notorious Marangoni effect, which leads to the formation of a severely non-uniform active layer on a large scale. Thus, a rapid solidification strategy was proposed to accelerate the evaporation of toluene, a green solvent, at room temperature. This strategy simultaneously inhibits the Marangoni effect and …

Energy & Environmental Science

The design and synthesis of manganese oxide-based materials with high-rate performance and long cycle life is a major challenge for aqueous zinc-ion batteries (AZIBs). This research reports the presence of a synergistic collaboration between vacancies, lattice water and nickel ions on enhancing the hydrated protons hopping via the Grotthuss mechanism for high-performance zinc ion batteries. The Grotthuss mechanism allows for the efficient transfer of a proton charge without the actual movement of the molecule over long distances, resulting in high ionic conductivity. NiMn3O7·3H2O achieves a capacity of 318 mA h g−1 under 200 mA g−1 and 121 mA h g−1 under 5 A g−1 with a retention of 91% after 4000 cycles. The relationship between the remarkable performance and Grotthuss topochemistry is investigated using techniques including synchrotron X-ray absorption spectroscopy and density functional …

Energy & Environmental Science

The electrocatalytic nitrate reduction reaction (NO3RR) holds tremendous potential for remediating NO3− pollution in groundwater and obtaining clean ammonia (NH3). However, the currently reported NO3RR catalysts face challenges in achieving high conversion efficiency at low NO3− concentrations due to sluggish reaction kinetics. Herein, we present a highly efficient Mott–Schottky electrocatalyst, composed of an amorphous Co–B nanochain embedded in amorphous CoOx nanosheets (Co–B@CoOx). In 100 ppm NO3−–N, the Co–B@CoOx catalyst exhibits remarkable performance, achieving over 95% NO3− removal within 40 min at −0.90 V vs. reversible hydrogen electrode and nearly 100% NH3 selectivity at −0.80 V, surpassing the performance of both Co–B and CoOx catalysts. Furthermore, Co–B@CoOx demonstrates an ultra-low energy consumption of 0.39 kW h molNO3−1, establishing it as one of the …

Energy & Environmental Science

Electrochemical CO2 reduction (CO2RR) offers an environmentally friendly method to transform and harness sequestered CO2. While gas-phase electrolysis systems provide high efficiency, gas-phase electrolysis systems face challenges related to carbonate precipitate formation and crossover. In response, liquid-phase (bi)carbonates electrolysis systems based on the use of bipolar membrane (BPM) electrode assemblies have emerged. These systems not only streamline the carbon-capture and conversion process but also present economic benefits. However, liquid-phase (bi)carbonate electrolysis cells suffer limited stability and selectivity at relevant operating current. Here, utilizing a Ni-based single-atom catalyst (Ni-SAC) and bicarbonate electrolyte, we demonstrate exceptional CO Faradaic efficiency (93%) at a partial current density of -186 mA cm-2 at -3.7 V for over 18 hours with an integrated carbon …

Energy & Environmental Science

Rechargeable aqueous zinc ion batteries (RAZIBs) have the potential for large scale energy storage due to their environmental friendliness, high safety and low cost. The trade-off between charging/discharging kinetics and stability has been the bottleneck of most cathode materials, which impedes the rate performance and cycle life of RAZIBs. Here we break the trade-off by designing vacancy-rich and Al-doped birnessite-type MnO2 nanosheet (Alx–MnO2) electrodes, which are synthesized by electrochemically oxidizing manganese based layered double hydroxides (MnAl-LDHs). Rich Al cation vacancies formed during the process of electrochemical oxidation provide three-dimensional diffusion channels for the storage of Zn ions, and the remaining Al atoms benefit the structural stability by suppressing the Jahn–Teller distortion of Mn(III)O6 polyhedra during battery cycling. As a result, by employing the optimized …

Energy & Environmental Science

The recent tremendous progress in monolithic perovskite-based double-junction solar cells is just the start of a new era of ultra-high-efficiency multi-junction photovoltaics. We report on triple-junction perovskite–perovskite–silicon solar cells with a record power conversion efficiency of 24.4%. Optimizing the light management of each perovskite sub-cell (∼1.84 and ∼1.52 eV for top and middle cells, respectively), we maximize the current generation up to 11.6 mA cm−2. Key to this achievement was our development of a high-performance middle perovskite sub-cell, employing a stable pure-α-phase high-quality formamidinium lead iodide perovskite thin film (free of wrinkles, cracks, and pinholes). This enables a high open-circuit voltage of 2.84 V in a triple junction. Non-encapsulated triple-junction devices retain up to 96.6% of their initial efficiency if stored in the dark at 85 °C for 1081 h.

Energy & Environmental Science

Zinc-ion batteries (ZIBs) have emerged as a promising candidate due to the abundance, low cost and high energy density. However, the performance of ZIBs needs to be improved to meet the practical requirements of energy storage systems. This work probes the efficacy of co-intercalation as a strategy for enhancing the electrochemical performance of ZIBs through the fabrication of sodium and copper co-intercalated birnessite manganese oxide (NCMO) cathodes. The results show that the co-intercalation of sodium and copper ions catalyzes the activation of copper cations on the surface Mn2+/Mn4+ redox pair, leading to improved specific capacity and cycling stability. The NCMO cathode exhibits a remarkable specific capacity of 576 mAh g-1 after 100 cycles at a low loading of around ~1 mg cm-2 and a high areal capacity of 2.10 mAh cm-2 at a high loading of ~10.9 mg cm-2. The mechanism of copper ions to …

Energy & Environmental Science

Surface post-treatment using larger organic spacer cations is widely recognized as one of the most effective approaches to suppress the defects and reconstruct microstructures in perovskite films. However, larger organic spacer cations always cause structural transformation to an uncontrollable low-dimensional phase at the perovskite surface, significantly restricting charge transport across interfaces within perovskite solar cells (PSCs). In this study, we introduce a bi-molecular competitive adsorption strategy using phenylmethylammonium iodide (PMAI) and octylammonium iodide (OAI) as co-modifiers from molecular dynamics perspectives. It is revealed that OA+ preferentially adsorbs on the surface of perovskite films owing to its much greater molecular polarity and steric hindrance effects, thereby inhibiting PMA+-induced surface layer transformation into a low-dimensional structural phase. This strategy therefore …

Energy & Environmental Science

Correction for ‘Mimicking ion and water management in poultry breeding for highly reversible zinc ion batteries’ by Shengli Zhai et al., Energy Environ. Sci., 2023, 16, 5479–5489, https://doi.org/10.1039/D3EE03045H.

Energy & Environmental Science

Contouring or structuring of the lithium/ceramic electrolyte interface and therefore increasing its surface area has been considered as a possible strategy to increase the charging current in solid-state batteries without lithium dendrite formation and short-circuit. By coupling together lithium deposition kinetics and the me chanics of lithium creep within calculations of the current distribution at the interface, and leveraging a model for lithium dendrite growth, we show that efforts to avoid dendrites on charging by increasing the interfacial surface area come with significant limitations associated with the topography of rough surfaces. These limitations are sufficiently severe such that it is very unlikely contouring could increase charging currents while avoiding dendrites and short-circuit to the levels required. For example, we show a sinusoidal surface topography can only raise the charging current before dendrites occur by …

Energy & Environmental Science

Surface post-treatment using larger organic spacer cations is widely recognized as one of the most effective approaches to suppress the defects and reconstruct microstructures in perovskite films. However, larger organic spacer cations always cause structural transformation to an uncontrollable low-dimensional phase at the perovskite surface, significantly restricting charge transport across interfaces within perovskite solar cells (PSCs). In this study, we introduce a bi-molecular competitive adsorption strategy using phenylmethylammonium iodide (PMAI) and octylammonium iodide (OAI) as co-modifiers from molecular dynamics perspectives. It is revealed that OA+ preferentially adsorbs on the surface of perovskite films owing to its much greater molecular polarity and steric hindrance effects, thereby inhibiting PMA+-induced surface layer transformation into a low-dimensional structural phase. This strategy therefore …

Energy & Environmental Science

Two-dimensional (2D) metallic transition metal dichalcogenides (TMDs) are attracting increasing attention as promising electrode materials with fast ion/electron transport due to their ultrahigh electrical conductivities and layered structures. However, their further development is hindered by the inadequate understanding of energy storage mechanisms and electrochemistry upon charging/discharging processes. Herein, 2D metallic niobium diselenide (NbSe2) flakes are targeted to understand the underlying electrochemical reaction mechanism during sodiation/de-sodiation. The complementary characterizations, including operando synchrotron X-ray diffraction, Raman spectroscopy, X-ray absorption spectroscopy and electron microscopy, are performed to investigate the structural evolution of 2D metallic NbSe2 under electrochemical conditions. Different from conventional wisdom that believes reversible …

Energy & Environmental Science

The recent tremendous progress in monolithic perovskite-based double-junction solar cells is just the start of a new era of ultra-high-efficiency multi-junction photovoltaics. We report on triple-junction perovskite–perovskite–silicon solar cells with a record power conversion efficiency of 24.4%. Optimizing the light management of each perovskite sub-cell (∼1.84 and ∼1.52 eV for top and middle cells, respectively), we maximize the current generation up to 11.6 mA cm−2. Key to this achievement was our development of a high-performance middle perovskite sub-cell, employing a stable pure-α-phase high-quality formamidinium lead iodide perovskite thin film (free of wrinkles, cracks, and pinholes). This enables a high open-circuit voltage of 2.84 V in a triple junction. Non-encapsulated triple-junction devices retain up to 96.6% of their initial efficiency if stored in the dark at 85 °C for 1081 h.

Energy & Environmental Science

The graphite anodes with solvent co-intercalation mechanism exhibit excellent kinetics and cycling stability in sodium-ion batteries. However, the dramatic volume changes caused by solvent participation are challenging for interphasial conformality. Herein, we reveal the intercalation compounds degradation and solid electrolyte interphase (SEI) evolution of graphite at different sodiated state via capacity loss and fluctuation of Coulombic efficiency (CE) induced by calendar aging. The abnormal calendar aging depended on sodiated states is found, which appears as more severe capacity loss and lower CE in partially sodiated graphite anode. The deteriorated performance results from its high-staged intercalated phase transition accompanied by huge volume shrinkage. Under the effect of different intercalation degradation, the growth/destruction of SEI coexists on the partially sodiated graphite, compared to growth …

Energy & Environmental Science

The cyclic instability of Si-based anodes can be effectively alleviated by adding carbon nanotube (CNT) networks. However, the ion diffusion and electrochemical performance vary significantly depending on the type of CNTs added, particularly single-walled carbon nanotubes (SWCNTs) and multiwalled carbon nanotubes (MWCNTs), and the intrinsic mechanism remains unknown. Herein, we revealed that the large volume expansion of Si-based anodes leads to the acupuncture effect of short CNTs, with the compressive stress on the CNTs and the Li-ion (Li+) diffusion energy barriers in the solid electrolyte interphase (SEI) exhibiting a linear correlation. Both the SEI and carbon-coating are penetrated by short, thick CNTs with gigapascal (GPa)-scale compressive stress, thereby accelerating electrolyte decomposition and leading to a LiF-rich SEI and an increased Li+ diffusion barrier. In contrast, long, slender CNTs …