Highly stable manganese oxide cathode material enabled by Grotthuss topochemistry for aqueous zinc ion batteries

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 …

Three‐dimensional (3D) printing has the potential to revolutionize the way energy storage devices are designed and manufactured. In this paper, we explore the use of 3D printing in the design and production of energy storage devices, especially zinc‐ion batteries (ZIBs) and examine its potential advantages over traditional manufacturing methods. 3D printing could significantly improve the customization of ZIBs, making it a promising strategy for the future of energy storage. In particular, 3D printing allows for the creation of complex, customized geometries, and designs that can optimize the energy density, power density, and overall performance of batteries. Simultaneously, we discuss and compare the impact of 3D printing design strategies based on different configurations of film, interdigitation, and framework on energy storage devices with a focus on ZIBs. Additionally, 3D printing enables the rapid prototyping …

Journal of Energy Chemistry

Zeolite-encapsulated metal nanoclusters are at the heart of bifunctional catalysts, which hold great potential for petrochemical conversion and the emerging sustainable biorefineries. Nevertheless, efficient encapsulation of metal nanoclusters into a high-silica zeolite Y in particular with good structural integrity still remains a significant challenge. Herein, we have constructed Ru nanoclusters (∼1 nm) encapsulated inside a high-silica zeolite Y (SY) with a SiO2/Al2O3 ratio (SAR) of 10 via a cooperative strategy for direct zeolite synthesis and a consecutive impregnation for metal encapsulation. Compared with the benchmark Ru/H-USY and other analogues, the as-prepared Ru/H-SY markedly boosts the yields of pentanoic biofuels and stability in the direct hydrodeoxygenation of biomass-derived levulinate even at a mild temperature of 180 °C, which are attributed to the notable stabilization of transition states by the …

ScienceOpen Preprints

Passive radiative cooling coating, PolyCool, has been developed with a solar reflectance of 97.4% and emissivity at the atmospheric window of 91%. This coating utilizes porous polyethylene, characterized by a broad pore size for enhanced solar reflectance, and incorporates PDMS nanoparticles to augment emissivity at the atmospheric window. A method that enables the scalable and size-controlled synthesis of PDMS nanoparticles has been established. Additionally, a technique for creating a porous structure coating using low-density polyethylene has also been developed. The microstructure and coating thickness can be precisely controlled throughout the coating process. In comparison to traditional methods for manufacturing superhydrophobic surfaces, our approach allows for the rapid preparation of a pure polyethylene-based surface with minimal equipment and material costs. The coating could also be deposited flexibly on various substrates, including metal.

Small

Designing a cost‐effective and multifunctional separator that ensures dendrite‐free and stable Zn metal anode remains a significant challenge. Herein, a multifunctional cellulose‐based separator is presented consisting of industrial waste‐fly ash particles and cellulose nanofiber using a facile solution‐coating method. The resulting fly ash‐cellulose (FACNF) separators enable a high ion conductivity (5.76 mS cm−1) and low desolvation energy barrier of hydrated Zn2+. These features facilitate fast ion transfer kinetics and inhibit water‐induced side reactions. Furthermore, experimental results and theoretical simulations confirm that the presence of fly ash particles in FACNF separators effectively accommodate the preferential deposition of Zn(002) planes, due to the weak chemical affinity between Zn(002) plane and fly ash, to mitigate dendrite formation and growth. Consequently, the utilization of FACNF separators …

Angewandte Chemie International Edition

Ammonia synthesis holds significant importance for both agricultural fertilizer production and emerging green energy applications. Here, we present a comprehensive characterization of a catalyst for mechanochemical ammonia synthesis, based on Cs‐promoted Fe. The study sheds light on the catalyst's dynamic evolution under reaction conditions and the origin of deactivation. Initially, elemental Cs converts to CsH, followed by partial CsOH formation due to trace oxygen impurities on the surface of the Fe metal and the equipment. Concurrently, the mechanical milling process comminutes Fe, exposing fresh metallic Fe surfaces. This comminution correlates with an induction period observed during ammonia formation. Critical to the study, degradation of active Cs promoter species (CsH and CsNH2) into inactive CsOH emerged as the primary deactivation mechanism. By increasing the Cs content from 2.2 mol% to …

Efficient electrocatalysts are pivotal for advancing green energy conversion technologies. Organic electrocatalysts, as cost‐effective alternatives to noble‐metal benchmarks, have garnered attention. However, the understanding of the relationships between their properties and electrocatalytic activities remains ambiguous. Plenty of research articles regarding low‐cost organic electrocatalysts started to gain momentum in 2010 and have been flourishing recently though, a review article for both entry‐level and experienced researchers in this field is still lacking. This review underscores the urgent need to elucidate the structure–activity relationship and design suitable electrode structures, leveraging the unique features of organic electrocatalysts like controllability and compatibility for real‐world applications. Organic electrocatalysts are classified into four groups: small molecules, oligomers, polymers, and frameworks …

Battery Energy

The utilization of biomass materials that contain abundant carbon–oxygen/nitrogen functional groups as precursors for the synthesis of carbon materials presents a promising approach for energy storage and conversion applications. Porous carbon materials derived from biomass are commonly employed as electric‐double‐layer capacitors in aqueous electrolytes. However, there is a lack of detailed discussion and clarification regarding the kinetics analysis and energy storage mechanisms associated with these materials. This study focuses on the modification of starch powders through the KOH activation process, resulting in the production of porous carbon with tunable nitrogen/oxygen functional groups. The kinetics and energy storage mechanism of this particular material in both acid and alkaline aqueous electrolytes are investigated using in situ attenuated total reflectance‐infrared in a three‐electrode …

Journal of Materials Chemistry A

Here, we introduce a highly robust and damage/contamination-recoverable superhydrophobic surface consisting of 1H,1H,2H,2H-perfluorooctyltriethoxysilane bonded titanium dioxide nanoparticles (PFOTES/TiO2 NPs) and ultra-high-molecular-weight polyethylene (UHMWPE). The addition of PFOTES/TiO2 NPs into UHMWPE transformed the surface wettability from the Wenzel to the Cassie–Baxter state. The superhydrophobicity of the surfaces remained after 80 or 100 cycles of sand dropping, sandpaper abrasion and adhesive tape peeling, and even after making 2000 scalpel scratches. They were stable under heat at 180 °C and repellent to water droplets with various water pH levels. The mechanical compression, impact, and bending tests showed that the mechanical strengths of the superhydrophobic surfaces were more prominent than those of high-strength cement, a highly robust material. Even when the …

Advanced Materials

Aqueous zinc‐ion batteries (AZIBs) have experienced a rapid surge in popularity, as evident from the extensive research with over 30 000 articles published in the past 5 years. Previous studies on AZIBs have showcased impressive long‐cycle stability at high current densities, achieving thousands or tens of thousands of cycles. However, the practical stability of AZIBs at low current densities (<1C) is restricted to merely 50–100 cycles due to intensified cathode dissolution. This genuine limitation poses a considerable challenge to their transition from the laboratory to the industry. In this study, leveraging density functional theory (DFT) calculations, an artificial interphase that achieves both hydrophobicity and restriction of the outward penetration of dissolved vanadium cations, thereby shifting the reaction equilibrium and suppressing the vanadium dissolution following Le Chatelier's principle, is described. The …

Nano Select

The prevalence of the SARS‐CoV‐2 virus has led to an increased focus on cleaning and disinfecting surfaces in the community and hospitals. An inherently antibacterial thin film is reported to combat the transmission of microbes on glass surfaces that could be accessed by the public, reducing the need for constant cleaning. The copper nanoparticle thin film is synthesized via a sol–gel method and deposited using a dip‐coater to create a transparent, rugged film resistant to scratching. The antibacterial performance is tested by a droplet and an aerosol deposition technique, where Escherichia coli and Staphylococcus aureus are sprayed directly onto the thin film, replicating coughs and sneezes: a common form of microbial transmission. The mechanism of antibacterial performance is studied by introducing reactive oxygen species quenchers to the thin film. This research presents copper nanoparticle thin films as …

Chemical Engineering Journal

The high-performance miniaturized micro-supercapacitors exhibit great potential due to their inherent properties of high-power density, fast charge–discharge rates, long cycle life, and wide working temperature range. However, there is a need to further enhance the energy density of micro-supercapacitors. In this study, we investigate a hybrid electrode material combination comprising activated carbon (AC) and polymer poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) to fabricate symmetric micro-supercapacitors (SMSCs) and employ the advanced Microplotter technique for the effective loading of active materials onto microelectrodes. The combination of AC and PEDOT:PSS is fine-tuned to attain optimal charge storage. This involves leveraging the synergistic impact of electrical double-layer capacitance from AC and pseudocapacitance from PEDOT:PSS, resulting in enhanced charge …

Disordered materials (DMs) have become promising materials in the advancement of lithium-ion batteries (LIBs). Their disordered, open structure is conductive to facilitate efficiency lithium-ion storage. DMs with tunable compositions also possess abundant defects that can interact with Li+, further enhancing their electrochemical performances in LIBs. Yet, revealing the structural origin of the superior electrochemical properties of DM-based LIBs remains a challenge. In this article, we review recent advances in the development of DM-based components for LIBs, such as anodes, cathodes, coating layers, and solid-state electrolytes. We describe the primary preparation and characterization methods utilized for DMs, while also describing the mechanisms involved in DM synthesis. This review article also addresses the correlation between the structural properties of DMs and their electrochemical performances …

The paper discusses the progress and commercialization of binders for energy storage applications, such as batteries. It explains the role of binders in holding together active materials and current collectors, and highlights the challenges associated with conventional organic solvents in binders. The potential of aqueous binders is introduced as a cost-effective and environmentally friendly alternative. The advantages and limitations of different types of binders are discussed, and the importance of binder selection for optimal battery performance is emphasized. The current state of commercialization of binders is reviewed, and the need for collaboration between researchers, manufacturers, and policymakers to develop and promote environmentally friendly and cost-effective binders is emphasized. The paper concludes by outlining future directions for research and development to further improve the performance and commercialization of binders, while addressing limitations such as lack of standardization, high cost, and long-term stability and reliability.

Nature Communications

Ammonia is a storage molecule for hydrogen, which can be released by catalytic decomposition. Inexpensive iron catalysts suffer from a low activity due to a too strong iron-nitrogen binding energy compared to more active metals such as ruthenium. Here, we show that this limitation can be overcome by combining iron with cobalt resulting in a Fe-Co bimetallic catalyst. Theoretical calculations confirm a lower metal-nitrogen binding energy for the bimetallic catalyst resulting in higher activity. Operando spectroscopy reveals that the role of cobalt in the bimetallic catalyst is to suppress the bulk-nitridation of iron and to stabilize this active state. Such catalysts are obtained from Mg(Fe,Co)2O4 spinel pre-catalysts with variable Fe:Co ratios by facile co-precipitation, calcination and reduction. The resulting Fe-Co/MgO catalysts, characterized by an extraordinary high metal loading reaching 74 wt.%, combine the …

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 …