ENN (China)

Abstract Limited by the size of microelectronics, as well as the space of electrical vehicles, there are tremendous demands for lithium-ion batteries with high volumetric energy densities. Current lithium-ion batteries, however, adopt graphite-based anodes with low tap density and gravimetric capacity, resulting in poor volumetric performance metric. Here, by encapsulating nanoparticles of metallic tin in mechanically robust graphene tubes, we show tin anodes with high volumetric and gravimetric capacities, high rate performance, and long cycling life. Pairing with a commercial cathode material LiNi 0.6 Mn 0.2 Co 0.2 O 2 , full cells exhibit a gravimetric and volumetric energy density of 590 W h Kg −1 and 1,252 W h L −1 , respectively, the latter of which doubles that of the cell based on graphite anodes. This work provides an effective route towards lithium-ion batteries with high energy density for a broad range of applications.

Abstract The application of graphene for electrochemical energy storage has received tremendous attention; however, challenges remain in synthesis and other aspects. Here we report the synthesis of high-quality, nitrogen-doped, mesoporous graphene particles through chemical vapor deposition with magnesium-oxide particles as the catalyst and template. Such particles possess excellent structural and electrochemical stability, electronic and ionic conductivity, enabling their use as high-performance anodes with high reversible capacity, outstanding rate performance (e.g., 1,138 mA h g −1 at 0.2 C or 440 mA h g −1 at 60 C with a mass loading of 1 mg cm −2 ), and excellent cycling stability (e.g., >99% capacity retention for 500 cycles at 2 C with a mass loading of 1 mg cm −2 ). Interestingly, thick electrodes could be fabricated with high areal capacity and current density (e.g., 6.1 mA h cm −2 at 0.9 mA cm −2 ), providing an intriguing class of materials for lithium-ion batteries with high energy and power performance.

Recently, perovskite/Si devices have attracted enormous interest as an ideal technology for tandem cells, particularly due to the attributes from perovskite cell including low temperature processibility, tunable optical bandgap, and high open circuit voltage. Although solution process is considered to be cost effective and more widely adoptable for perovskite subcell, to the best of our knowledge, there has been no successful demonstration for the resulting high performance two‐terminal perovskite/Si cells. In this manuscript, solution process is employed to fabricate the key components in the two‐terminal perovskite/Si tandem solar cell, including tunneling junction and the perovskite absorber. The current density match between both cells is thoroughly studied by varing the perovskite bandgap from ≈1.55 to 1.69 eV. It was also revealed that the photovoltage modulation in the device is primarily associated to the band alignment over the perovskite and the tunneling materials. Therefore, a reverse scanned power conversion efficiency over 20% is demonstrated, the most efficient two‐terminal perovskite/Si device based on solution processed perovskite subcells.

Abstract A new lower tungsten divertor has been developed and installed in the EAST superconducting tokamak to replace the previous graphite divertor with power handling capability increasing from <2 MW m −2 to ∼10 MW m −2 , aiming at achieving long-pulse H-mode operations in a full metal wall environment with the steady-state divertor heat flux of ∼10 MW m −2 . A new divertor concept, ‘corner slot’ (CS) divertor, has been employed. By using the ‘corner effect’, a strongly dissipative divertor with the local buildup of high neutral pressure near the corner can be achieved, so that stable detachment can be maintained across the entire outer target plate with a relatively lower impurity seeding rate, at a separatrix density compatible with advanced steady-state core scenarios. These are essential for achieving efficient current drive with low-hybrid waves, a low core impurity concentration and thus a low loop voltage for fully non-inductive long-pulse operations. Compared with the highly closed small-angle-slot divertor in DIII-D, the new divertor in EAST exhibits the following merits: (1) a much simpler geometry with integral cassette body structure, combining vertical and horizontal target plates, which are more suitable for actively water-cooled W/Cu plasma facing components, facilitating installation precision control for minimizing surface misalignment, achieving high engineering reliability and lowering the capital cost as well; (2) it has much greater flexibility in magnetic configurations, allowing for the position of the outer strike point on either vertical or horizontal target plates to accommodate a relatively wide triangularity range, δ l = 0.4–0.6, thus enabling to explore various advanced scenarios. A water-cooled copper in-vessel coil has been installed under the dome. Five supersonic molecular beam injection systems have been mounted in the divertor to achieve faster and more precise feedback control of the gas injection rate. Furthermore, this new divertor allows for double null divertor operation and slowly sweeping the outer strike point across the horizontal and vertical target plates to spread the heat flux for long-pulse operations. Preliminary experimental results demonstrate the ‘corner effect’ and are in good agreement with simulations using SOLPS-ITER code including drifts. The EAST new divertor provides a test-bed for the closed divertor concept to achieve steady-state detachment operation at high power. Next step, a more closed divertor, ‘sharp-cornered slot’ divertor, building upon the current CS divertor concept, has been proposed as a candidate for the EAST upper divertor upgrade.

Lithium iron phosphate (LiFePO4) is broadly used as a low-cost cathode material for lithium-ion batteries, but its low ionic and electronic conductivity limit the rate performance. We report herein the synthesis of LiFePO4/graphite composites in which LiFePO4 nanoparticles were grown within a graphite matrix. The graphite matrix is porous, highly conductive, and mechanically robust, giving electrodes outstanding cycle performance and high rate capability. High-mass-loading electrodes with high reversible capacity (160 mA h g–1 under 0.2 C), ultrahigh rate capability (107 mA h g–1 under 60 C), and outstanding cycle performance (>95% reversible capacity retention over 2000 cycles) were achieved, providing a new strategy toward low-cost, long-life, and high-power batteries. Adoption of such material leads to electrodes with volumetric energy density as high as 427 W h L–1 under 60 C, which is of great interest for electric vehicles and other applications.

We report thermoelectric transport studies on Bi₂Se₃ topological insulator thin films with varied thickness grown by molecular beam epitaxy. We find that the Seebeck coefficient and thermoelectric power factor decrease systematically with the reduction of film thickness. These experimental observations can be explained quantitatively by theoretical calculations based on realistic electronic band structure of the Bi₂Se₃ thin films. Lastly, this work illustrates the crucial role played by the topological surface states on the thermoelectric transport of topological insulators, and sheds new light on further improvement of their thermoelectric performance.

Full suppression of type-I edge localized modes (ELMs) using n = 4 resonant magnetic perturbations (RMPs) as planned for ITER has been demonstrated for the first time (n is the toroidal mode number of the applied RMP). This is achieved in EAST plasmas with low input torque and tungsten divertor, and the target plasma for these experiments in EAST is chosen to be relevant to the ITER Q = 10 operational scenario, thus also addressing significant scenario issues for ITER. In these experiments the lowest neutral beam injection (NBI) input torque is around TNBI ∼ 0.44 Nm, which extrapolates to around 14 Nm in ITER (compared to a total torque input of 35 Nm when 33 MW of NBI are used for heating). The q95 is around 3.6 and normalized plasma beta βN ∼ 1.5–1.8, similar to that in the ITER Q = 10 scenario. Suppression windows in both q95 and plasma density are observed; in addition, lower plasma rotation is found to be favourabe to access ELM suppression. ELM suppression is maintained with line averaged density up to 60%nGW (Greenwald density limit) by feedforward gas fuelling after suppression is achieved. It is interesting to note that in addition to an upper density, a low density threshold for ELM suppression of 40%nGW is also observed. In these conditions energy confinement does not significantly drop (<10%) during ELM suppression when compared to the ELMy H-mode conditions, which is much better than previous results using low n (n = 1 and 2) RMPs in higher q95 regimes. In addition, the core plasma tungsten concentration is clearly reduced during ELM suppression demonstrating an effective impurity exhaust. MHD response modelling using the MARS-F code shows that edge magnetic field stochasticity has a peak at q95 ∼ 3.65 for the odd parity configuration, which is consistent to the observed suppression window around 3.6–3.75. These results expand the physical understanding of ELM suppression and demonstrate the effectiveness of n = 4 RMPs for reliable control ELMs in future ITER high Q plasma scenarios with minimum detrimental effects on plasma confinement.

Multi-Party Computation (MPC) provides an effective cryptographic solution for distributed computing systems so that local models with sensitive information are encrypted before sending to the centralized servers for aggregation. Though direct local knowledge leakages are eliminated in MPC-based algorithms, we observe the server can still obtain the local information indirectly in many scenarios, or even reveal the groundtruth images through methods like Deep Leakage from Gradients (DLG). To eliminate such possibilities and provide stronger protections, we propose an augmented MPC approach by encrypting local models with two rounds of decomposition before transmitting to the server. The proposed solution allows us to remove the constraint that servers must be honest in the general federated learning settings since the true global model is hidden from the servers. Specifically, the augmented MPC algorithm encodes local models into multiple secret shares in the first round, then each share is furthermore split into a public share and a private share. Consequences of such a two-round decomposition are that the augmented algorithm fully inherits the advantages of standard MPC by providing lossless encryption and decryption while simultaneously rendering the global model invisible to the central server. Both theoretical analysis and experimental verification demonstrate that such an augmented solution can provide stronger protections for the security and privacy of the training data, with minimal extra communication and computation costs incurred.

Central to the design and execution of nanocomposite strategies is the invention of polymer-affinitive and multifunctional nanoreinforcements amenable to economically viable processing. Here, a microwave-assisted approach enabled gram-scale fabrication of polymer-affinitive luminescent quantum dots (QDs) from spent coffee grounds. The ultrasmall dimensions (approaching 20 nm), coupled with richness of diverse oxygen functional groups, conferred the zero-dimensional QDs with proper exfoliation and uniform dispersion in poly(l-lactic acid) (PLLA) matrix. The unique optical properties of QDs were inherited by PLLA nanocomposites, giving intensive luminescence and high visible transparency, as well as nearly 100% UV-blocking ratio in the full-UV region at only 0.5 wt % QDs. The strong anchoring of PLLA chains at the nanoscale surfaces of QDs facilitated PLLA crystallization, which was accompanied by substantial improvements in thermomechanical and tensile properties. With 1 wt % QDs, for example, the storage modulus at 100 °C and tensile strength increased over 2500 and 69% compared to those of pure PLLA (4 and 57.3 MPa), respectively. The QD-enabled energy-dissipating and flexibility-imparting mechanisms upon tensile deformation, including the generation of numerous shear bands, crazing, and nanofibrillation, gave an unusual combination of elasticity and extensibility for PLLA nanocomposites. This paves the way to biowaste-derived nanodots with high affinity to polymer for elegant implementation of distinct light management and extreme nanoreinforcements in an ecofriendly manner.

ENN Science and Technology Development Co., Ltd. (ENN) is committed to generating fusion energy in an environmentally friendly and cost-effective manner, which requires abundant aneutronic fuel. Proton-boron (p-11B or p-B) fusion is considered an ideal choice for this purpose. Recent studies have suggested that p-B fusion, although challenging, is feasible based on new cross section data, provided that a hot ion mode and high wall reflection can be achieved to reduce electron radiation loss. The high beta and good confinement of the spherical torus (ST) make it an ideal candidate for p-B fusion. By utilizing the new spherical torus energy confinement scaling law, a reactor with a major radius R0=4 m, central magnetic field B0=6 T, central temperature Ti0=150 keV, plasma current Ip=30 MA, and hot ion mode Ti/Te=4 can yield p-B fusion with Q&amp;gt;10. A roadmap for p-B fusion has been developed, with the next-generation device named EHL-2. EHL stands for ENN He-Long, which literally means “peaceful Chinese Loong.” The main target parameters include R0≃1.05 m, A≃1.85, B0≃3 T, Ti0≃30 keV, Ip≃3 MA, and Ti/Te≥2. The existing ST device EXL-50 was simultaneously upgraded to provide experimental support for the new roadmap, involving the installation and upgrading of the central solenoid, vacuum chamber, and magnetic systems. The construction of the upgraded ST fusion device, EXL-50U, was completed at the end of 2023, and it achieved its first plasma in January 2024. The construction of EHL-2 is estimated to be completed by 2026.

Chalcogenides have been considered as promising thermoelectric materials because of their low cost, nontoxicity, and environmental benignity. In this work, we synthesized a series of Cu2S1–xTex (0 ≤ x ≤ 1) alloys by a facile, rapid method of mechanical alloying combined with spark plasma sintering process. The Cu2S1–xTex system provides an excellent vision of the competition between pure phase and phase transformation, entropy-driven solid solution, and enthalpy-driven phase separation. When the Te concentration increases, the Cu2S1–xTex system changed from the pure monoclinic Cu2S at x = 0 to monoclinic Cu2S1–xTex solid solution at 0.02 ≤ x ≤ 0.06 and then transforms to hexagonal Cu2S1–xTex solid solution at 0.08 ≤ x ≤ 0.1. The phase separation of hexagonal Cu2Te in the hexagonal Cu2S matrix occurs at 0.3 ≤ x ≤ 0.7 and finally forms the hexagonal Cu2Te at x = 1. Owing to the changed band structure and the coexisted Cu2S and Cu2Te phases, greatly enhanced power factor was achieved in all Cu2S1–xTex (0 < x < 1) alloys. Meanwhile, the point defect introduced by the substitution of Te/S atoms strengthened the phonon scattering, resulting in a lowered lattice thermal conductivity in most of these solid solutions. As a consequence, Cu2S0.94Te0.06 exhibits a maximum ZT value of 1.18 at 723 K, which is about 3.7 and 14.8 times as compared to the values of pristine Cu2S (0.32) and Cu2Te (0.08), respectively.

Abstract As a new spherical tokamak designed to simplify the engineering requirements of a possible future fusion power source, the EXL-50 experiment features a low aspect ratio vacuum vessel (VV), encircling a central post assembly containing the toroidal field coil conductors without a central solenoid. Multiple electron cyclotron resonance heating (ECRH) resonances are located within the VV to improve current drive effectiveness. Copious energetic electrons are produced and measured with hard x-ray detectors, carry the bulk of the plasma current ranging from 50–150 kA, which is maintained for more than 1 s duration. It is observed that over one ampere current can be sustained per watt of ECRH power issued from the 28 GHz gyrotrons. The plasma current reaches I p &gt; 80 kA for high density (&gt;5 × 10 18 m −2 ) discharge with 150 kW ECRH. An analysis was carried out combining reconstructed multi-fluid equilibrium, guiding-center orbits of energetic electrons, and resonant heating mechanisms. It is verified that in EXL-50 a broadly distributed current of energetic electrons creates a smaller closed magnetic-flux surface of low aspect ratio that in turn confines the thermal plasma electrons and ions and participate in maintaining the equilibrium force balance.

Experiments have been carried out at the EAST tokamak to study ITER-relevant scenario integration issues, related to edge localized mode (ELM) control in H-mode plasmas by the application of three-dimensional (3D) resonant magnetic perturbations (RMPs), which have a large impact on the execution of the ITER research plan. The EAST experiments have successfully demonstrated ELM suppression at normalized torque inputs similar to ITER. The application of RMP fields with high toroidal mode number (n = 4) reduces the impact of ELM control on energy and particle confinement compared to those use lower n (n = 1, 2) RMPs. Injection of successive pellets is found to be effective in increasing the plasma density in ELM-suppressed H-modes and reducing the divertor power without triggering large ELMs at EAST. Access to high recycling and radiative divertor conditions while maintaining ELM suppression has been demonstrated in EAST by the use of gas fuelling and neon impurity seeding. Both approaches have been found to be effective in reducing power fluxes to the divertor strike points in near-separatrix lobes for both n = 2 and n = 4 RMPs. Furthermore, reduction of power fluxes in off-separatrix lobes is only effective for n = 4 RMP application, which is consistent with magnetic topology modelling (including plasma response) results showing a shallow penetration into the confined plasma region of field lines connected to these lobes compared to n = 2. The EAST results support the use of high n 3D fields for ELM suppression in ITER high Q_DT scenarios since they provide optimum integration features regarding energy and particle confinement, pellet fuelling, radiative divertor operation while eliminating ELM transient power loads and being compatible with low torque input.

Abstract The ion temperature anisotropy instability is widely thought of as a constraint on the distribution of the ion perpendicular and parallel temperatures in the solar wind. Besides the ion temperature anisotropy, proton and alpha particle beams are permeating in the solar wind. Therefore, this paper presents a comprehensive investigation on unstable waves resulting from both ion temperature anisotropy and ion beams. It finds that the strongest electromagnetic cyclotron instability triggers the left-hand circularly polarized Alfvén/proton-cyclotron wave propagating along the background magnetic field. The strongest fast-magnetosonic/whistler firehose instability generates the right-hand circularly polarized fast-magnetosonic/whistler wave propagating reversely to the background magnetic field. The mirror instability preferably drives oblique mirror mode waves with two anticorrelated perpendicular magnetic components. The Alfvén firehose instability is prior to generating oblique Alfvén waves with two unbalanced perpendicular magnetic components that are nearly positive-correlated. Due to the effects of streaming proton and alpha particles, both the mirror and Alfvén firehose instabilities produce slowly propagating unstable waves in comparison to nonpropagating waves in motionless plasmas. The differential proton and alpha particle flows result in the ion/ion beam instability, destabilizing obliquely propagating Alfvén/proton-cyclotron waves. The ion/ion beam instability can provide a constraint on electromagnetic fluctuations in the low-beta region. Moreover, this paper clearly explores the dependence of the frequency and electromagnetic polarization on the normal angle for each kind of instability, which could be useful for distinguishing the instability mechanism in the solar wind.

In this paper, using the infinite time-evolving block decimation (iTEBD) algorithm and Bell-type inequalities, we investigate multipartite quantum nonlocality in an infinite one-dimensional quantum spin-$\frac{1}{2} XXZ$ system. High hierarchy of multipartite nonlocality can be observed in the gapless phase of the model, while only the lowest hierarchy of multipartite nonlocality is observed in most regions of the gapped antiferromagnetic phase. Thereby, Bell-type inequalities disclose different correlation structures in the two phases of the system. Furthermore, at the infinite-order quantum phase transition (QPT, or Kosterlitz-Thouless QPT) point of the model, the correlation measures always show a local minimum value, regardless of the length of the subchains. It indicates that relatively low hierarchy of multipartite nonlocality would be observed at the infinite-order QPT point in a Bell-type experiment. The result is in contrast to the existing results of the second-order QPT in the one-dimensional $XY$ model, where multipartite nonlocality with the highest hierarchy has been observed. Thus, multipartite nonlocality provides an alternative perspective to distinguish between these two kinds of QPTs. Reliable clues for the existence of tripartite quantum entanglement have also been found.

Building form has significant effects on energy use in buildings, especially in cold climate regions. This research is focused on exploring the influences of parameters relevant to building forms on energy use for office buildings in Harbin, China. The input parameters include building orientation, aspect ratios, window-wall ratio, number of floors, and overall scales. The results show that the number of floors is the only dominant variable that affects annual heating energy use intensity, while the overall building scale is the most critical factor influencing both cooling and electricity use per unit of floor area. The comparison of results derived from machine learning methods indicates that the bagging MARS (Multivariate Adaptive Regression Splines), MARS, RF (random forest) are better models in predicting annual heating use. By contrast, the GP (Gaussian process) and bagging MARS are two most effective models for estimating both cooling and electricity use. The prediction for cooling and electricity intensities is more difficult than heating energy use in this case.

The integration of Foundation Models (FMs) with Federated Learning (FL) presents a transformative paradigm in Artificial Intelligence (AI). This integration offers enhanced capabilities, while addressing concerns of privacy, data decentralization and computational efficiency. This paper provides a comprehensive survey of the emerging field of Federated Foundation Models (FedFM), elucidating their synergistic relationship and exploring novel methodologies, challenges, and future directions that the FL research field needs to focus on in order to thrive in the age of FMs. A systematic multi-tiered taxonomy is proposed, categorizing existing FedFM approaches for model training, aggregation, trustworthiness, and incentivization. Key challenges, including how to enable FL to deal with high complexity of computational demands, privacy considerations, contribution evaluation, and communication efficiency, are thoroughly discussed. Moreover, this paper explores the intricate challenges of communication, scalability and security inherent in training/fine-tuning FMs via FL. It highlights the potential of quantum computing to revolutionize the processes of training, inference, optimization and security. This survey also introduces the implementation requirement of FedFM and some practical FedFM applications. It highlights lessons learned with a clear understanding of our findings for FedFM. Finally, this survey not only provides insights into the current state and challenges of FedFM, but also offers a blueprint for future research directions, emphasizing the need for developing trustworthy solutions. It serves as a foundational guide for researchers and practitioners interested in contributing to this interdisciplinary and rapidly advancing field.

Abstract The calculation of fusion reactivity involves a complex six-dimensional integral that takes into account the fusion cross section and velocity distributions of two reactants. However, a more simplified one-dimensional integral form can be useful in certain cases, such as for studying fusion yield or diagnosing ion energy spectra. This simpler form has been derived in a few special cases, such as for a combination of two Maxwellian distributions, a beam-Maxwellian combination, and a beam-target combination, and can greatly reduce computational costs. In this study, it is shown that the reactivity for two drift bi-Maxwellian reactants with different drift velocities, temperatures, and anisotropies can also be reduced to a one-dimensional form, unifying existing derivations into a single expression. This result is used to investigate the potential enhancement of fusion reactivity due to the combination of beam and temperature anisotropies. For relevant parameters in fusion energy, the enhancement factor can be larger than 20%, which is particularly significant for proton-boron (p–B11) fusion, as this factor can have a significant impact on the Lawson fusion gain criteria.

Abstract Non-Maxwellian distributions of particles are commonly observed in fusion studies, especially for magnetic confinement fusion plasmas. The particle distribution has a direct effect on fusion reactivity, which is the focus of this study. We investigate the effects of three types of non-Maxwellian distributions, namely drift-ring-beam, slowing-down, and kappa super-thermal distributions, on the fusion reactivities of D-T (Deuterium-Trillium) and p-B11 (proton-Boron) using a newly developed program, where the enhancement of fusion reactivity relative to the Maxwellian distribution is computed while keeping the total kinetic energy constant. The calculation results show that for the temperature ranges of interest to us, namely 5–50 keV for D-T and 100–500 keV for p-B11, these non-Maxwellian distributions can enhance the fusion reactivities. In the case of the drift-ring-beam distribution, the perpendicular ring beam velocity leads to decreased enhancement in low temperature range and increased enhancement in high temperature range. This effect is favorable for p-B11 fusion reaction and unfavorable for D-T fusion reaction. This is because the important temperature range for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mtext>p - B</mml:mtext> </mml:mrow> <mml:mn>11</mml:mn> </mml:math> fusion reaction significantly overlaps with the high temperature enhancement range, while the important temperature range for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mtext>D - T</mml:mtext> </mml:mrow> </mml:math> fusion significantly overlaps with the low temperature reduction range. In the slowing-down distribution, the birth speed plays a crucial role in both reactions, and increasing birth speed leads to a shift in the enhancement ranges towards lower temperatures, which is beneficial for both reactions. Finally, the kappa super-thermal distribution results in a relatively large enhancement in the low temperature range with a small high energy power-law index <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>κ</mml:mi> </mml:math> . Overall, this study provides insight into the effects of non-Maxwellian distributions on fusion reactivity and highlights potential opportunities for enhancing fusion efficiency.

The preparation methods of 2D metallic transition metal dichalcogenides (MTMDCs), such as chemical exfoliation, colloidal synthesis and chemical vapor deposition, as well as their applications in electrocatalytic hydrogen evolution reactions (HER), are comprehensively discussed. In addition, challenges regarding the preparation of MTMDC nanosheets, probable routes for further improving HER performance, and future research directions are proposed. More details can be found in article number 1801025 by Xiaoqin Yan, Yanfeng Zhang, and co-workers.