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Controllable adjustment of low-valent metal active sites near the pits can promote the WO3−x surface charge delocalization, which dominates the formation of *CHO intermediates, thus customizing a unique reaction pathway for CO2 reduction to CH3OH.

Background There is still a lack of effective scoring criteria for assessing the severity of pulmonary infection associated with changes in the endobronchial lining of the bronchus in children. This study aimed to ascertain the timing and value of endoscopic scoring of fibreoptic bronchoscopy (FOB) and bronchoalveolar lavage (BAL) in children with severe pneumonia. Method The clinical data of 229 children with severe pneumonia treated with BAL in the Pediatric Intensive Care Unit of the First Affiliated Hospital of Xinxiang Medical University between November 2018 and December 2021 were collected. According to the severity of the disease, patients were divided into an invasive ventilation group and a non-invasive ventilation group, as well as an early BAL group (receiving BAL within 1 day of admission) and a late BAL group (receiving BAL 2 days after admission). A Student’s t-test, Chi-square test, receiver operating characteristic (ROC) curve and survival curve were used to analyse the bronchitis score, aetiology of BAL fluid and survival data. Results The scores of endoscopic mucosal oedema, erythema and pallor and the total score in the invasive ventilation group were higher than those in the non-invasive ventilation group (P < 0.05), and they were consistent with the Sequential Organ Failure Assessment (SOFA) scores. The secretion colour score was lower in the early BAL group than in the late BAL group (P < 0.05). On the bronchitis scores, which were evaluated using a ROC curve, the difference in the mucosal erythema, pallor, oedema and total score of the invasive and non-invasive groups was statistically significant (P < 0.05), which was consistent with the area under the ROC of the SOFA scores. Acute Physiology and Chronic Health Assessment II and SOFA scores after FOB were lower than those before treatment (P < 0.05). In terms of ICU hospitalisation days and total hospitalisation days, the time of the early FOB patients was shorter than that of the late FOB patients (P < 0.05). A total of 22 patients (9.61%) died. The Kaplan–Meier analysis and log-rank test showed that the survival rate of the non-invasive ventilation group was higher than that of the invasive ventilation group (P < 0.05). Conclusion This study found that FOB combined with BAL is an important method for the diagnosis and treatment of severe pneumonia. Early BAL can reduce hospitalisation and ICU time; however, it cannot improve the survival rate. The endoscopic score has a certain role to play in assessing the severity of pulmonary inflammation, but studies with a large sample are still needed to confirm this.

Two-dimensional N-doped porous carbon nanosheets with well-developed porosity and enriched pyridinic N sites are fabricated by a simple impregnation–calcination strategy, and exhibit excellent electrochemical CO2-to-syngas activity and durability.

3D Pd aerogels with a controllable homojunction density are synthesized using an innovative melting–casting technology. The homojunction-rich Pd aerogels selectively reduce CO2 to CO with a 92.3% faradaic efficiency and durability over 10 h, benefiting from the strong coupling between the electrons and the adsorbed intermediates at the phase-mismatch interface.

A dendrite-suppressed, utilization-improved metallic Li anode was fabricated via a record-fast (1.0 s) infusion of molten Li into Pb-decorated carbon cloth at 250 °C.

The implementation of low-cost transition-metal complexes in CO2 reduction reaction (CO2RR) is hampered by poor mechanistic understanding. Herein, a carbon-supported copper bis-(terpyridine) complex enabling facile kilogram-scale production of the catalyst is developed. We directly observe an intriguing baton-relay-like mechanism of active sites transfer by employing a widely accessible operando Raman/Fourier-transform infrared spectroscopy analysis coupled with density functional theory computations. Our analyses reveal that the first protonation step involves Cu-N bond breakage before the *COOH intermediate forms exclusively at the central N site, followed by an N-to-Cu active site transfer. This unique active site transfer features energetically favorable *CO formation on Cu sites, low-barrier CO desorption and reversible catalyst regeneration, endowing the catalyst with a CO selectively of 99.5 %, 80 h stability, and a turn-over efficiency of 9.4 s−1 at −0.6 V vs. the reversible hydrogen electrode in an H-type cell configuration. We expect that the approach and findings presented here may accelerate future mechanistic studies of next-generation CO2RR electrocatalysts.

Solid electrolytes hold promise in safely enabling high-energy metallic sodium (Na) anodes. However, the poor Na‖solid electrolyte interfacial contact can induce Na dendrite growth and limit Na utilization, plaguing the rate performance and energy density of current solid-state Na-metal batteries (SSSMBs). Herein, a simple and scalable Pb/C interlayer strategy is introduced to regulate the surface chemistry and improve Na wettability of Na

Reducing the operating temperature of conventional molten sodium-sulfur batteries (∼350 °C) is critical to create safe and cost-effective large-scale storage devices. By raising the surface treatment temperature of lead acetate trihydrate, the sodium wettability on β''-Al2O3 improved significantly at 120 °C. The low temperature Na-S cell can reach a capacity as high as 520.2 mA h g-1 and stable cycling over 1000 cycles.

Capacity fading during long-term cycling (>1500×) is still a critical challenge for Li-ion batteries that use Ni-rich layered oxides, e.g. LiNi0.8Co0.15Al0.05O2 (NCA), as the cathode. Microcracks have been previously recognized as one of the primary reasons for the observed capacity fade. Although there exists a generally developed mechanical understanding of microcracks, the role of the electrolyte has not been clearly understood, especially after extended cycling and at the atomic scale. Here, we unveil the microstructural evolution of spherical NCA secondary particles after long-term cycling using scanning transmission electron microscopy accompanied with electron energy loss spectroscopy. We found that the microcracks initiated and grew through grain boundaries, which then serve as the pathway for electrolyte penetration into secondary NCA particles. Additionally, the rock-salt phase reconstruction is prone to occur at the (003) surfaces of the primary particles or the crack surfaces, largely due to electrolyte (LiPF6 EC/EMC) corrosion. Crack propagation within the NCA grains is primarily a joint consequence from electrolyte corrosion and mechanical strain during lithiation/delithiation. During extended cycling, due to the distinctive surface facets, the primary grains located in the center of the secondary particles experience more intensive electrolyte corrosion, leading to a reduced contact with nearby particles, impairing the overall capacity. These results establish the initiation and growth mechanism of microcracks and voids in NCA-based cathodes during cycling and point out the role of the electrolyte in affecting the degradation of NCA-based cathodes.

The developments of all-solid-state sodium batteries are severely constrained by poor Na-ion transport across incompatible solid-solid interfaces. We demonstrate here a triple NaxMoS2-carbon-BASE nanojunction interface strategy to address this challenge using the β″-Al2O3 solid electrolyte (BASE). Such an interface was constructed by adhering ternary Na electrodes containing 3 wt % MoS2 and 3 wt % carbon on BASE and reducing contact angles of molten Na to ∼45°. The ternary Na electrodes exhibited twice improved elasticity for flexible deformation and intimate solid contact, whereas NaxMoS2 and carbon synergistically provide durable ionic/electronic diffusion paths, which effectively resist premature interface failure due to loss of contact and improved Na stripping utilization to over 90%. Na metal hosted via triple junctions exhibited much smaller charge-transfer resistance and 200 h of stable cycling. The novel interface architecture enabled 1100 mAh/g cycling of all-solid-state Na-S batteries when using advanced sulfur cathodes with Na-ion conductive PEO10-NaFSI binder and NaxMo6S8 redox catalytic mediator.

Because of their structural versatility, fast redox reactivity, high storage capacity, sustainability, and environmental friendliness, soluble organic redox molecules have emerged as materials that have potential for use in energy-storage systems. Considering these advantages, this paper reviews recent progress in implementing such materials in aqueous soluble organic redox flow batteries and organic alkali metal/air batteries. We identify and discuss major challenges associated with molecular structures, cell configurations, and electrochemical parameters. Hopefully, we provide a general guidance for the future development of soluble organic redox materials for emerging energy-storage devices used in the electricity grid.

This review focuses on the Na wetting challenges and relevant strategies regarding stabilizing sodium-metal anodes in sodium-metal batteries (SMBs). The Na anode is the essential component of three key energy storage systems, including molten SMBs (i.e., intermediate-temperature Na-S and ZEBRA batteries), all-solid-state SMBs, and conventional SMBs using liquid electrolytes. We begin with a general description of issues encountered by different SMB systems and point out the common challenge in Na wetting. We detail the emerging strategies of improving Na wettability and stabilizing Na metal anodes for the three types of batteries, with the emphasis on discussing various types of tactics developed for SMBs using liquid electrolytes. We conclude with a discussion of the overlooked yet critical aspects (Na metal utilization, N/P ratio, critical current density, etc.) in the existing strategies for an individual battery system and propose promising areas (anolyte incorporation and catholyte modifications for lower-temperature molten SMBs, cell evaluation under practically relevant current density and areal capacity, etc.) that we believe to be the most urgent for further pursuit. Comprehensive investigations combining complementary post-mortem, in situ, and operando analyses to elucidate cell-level structure-performance relations are advocated.

Solid-state electrolytes (SSEs) hold a critical role in enabling high-energy-density and safe rechargeable batteries with Li metal anode. Unfortunately, nonuniform lithium deposition and dendrite penetration due to poor interfacial solid-solid contact are hindering their practical applications. Here, solid-state lithium naphthalenide (Li-Naph(s)) is introduced as a plastic monolithic mixed-conducting interlayer (PMMCI) between the garnet electrolyte and the Li anode via a facile cold process. The thin PMMCI shows a well-ordered layered crystalline structure with excellent mixed-conducting capability for both Li

Solar-driven CO

3D Pd aerogels with a controllable homojunction density are synthesized using an innovative melting-casting technology. The homojunction-rich Pd aerogels selectively reduce CO

Sodium (Na)-based battery technologies that are economical (because Na is abundant) and have long cycle life are gaining importance for large-scale energy storage applications. Among the widely studied Na-based battery systems, intermediate-temperature (IT) Na-metal halide (Na-MH) batteries have demonstrated several advantages over conventional high-temperature Na batteries, including superior battery safety, lower operating temperature and manufacturing cost, potentially longer cycle life, and easier assembly. However, the rate performance of IT Na-MH batteries is inevitably affected by the lower operating temperatures. In pursuit of faster charge-transfer reaction kinetics, we extended our studies of cathode materials beyond the extensively investigated NiCl2 to NiBr2 (NaBr/Ni) and NiI2 (NaI/Ni) compounds. We systematically investigated the synergetic effects of anion chemistry on the electrochemical properties. Surprisingly, among three tested cathodes, the NaBr/Ni cathode showed the highest energy density of 174 Wh/kg at 33.3 mA/cm2 (∼0.8C), which is 2.5 and 1.9 times higher than those of NaCl/Ni and NaI/Ni cells. We explored the underlying enhancement mechanism in great detail via multiple structural characterization and electrochemical techniques. The sodium-halide salt dissolution in molten NaAlCl4 was found to be the determining factor in rate improvement. Our findings will greatly advance IT Na-MH battery technologies and pave the way towards fundamental understanding of reaction kinetics for high-temperature batteries in general.

Ceramic-polymer composite electrolytes (CPEs) are being explored to achieve both high ionic conductivity and mechanical flexibility. Here, we show that, by incorporating 10 wt % (3 vol %) mixed-sized fillers of Li7La3Zr2O12 (LLZO) doped with Nb/Al, the room-temperature ionic conductivity of a polyvinylidene fluoride (PVDF)-LiClO4-based composite can be as high as 2.6 × 10-4 S/cm, which is 1 order of magnitude higher than that with nano- or micrometer-sized LLZO particles as fillers. The CPE also shows a high lithium-ion transference number of 0.682, a stable and low Li/CPE interfacial resistance, and good mechanical properties favorable for all-solid-state lithium-ion battery applications. X-ray photoelectron spectroscopy and Raman analysis demonstrate that the LLZO fillers of all sizes interact with PVDF and LiClO4. High packing density (i.e., lower porosity) and long conducting pathways are believed responsible for the excellent performance of the composite electrolyte filled with mixed-sized ionically conducting ceramic particles.

Layered Ni-rich oxides have attracted much attention for the positive electrode in lithium-ion batteries due to their low cost and high capacity. However, they still suffer from poor cycling and rate performance, especially at high voltage. In this work, LiNi0.6Co0.2Mn0.2O2 powders are surface-modified by a Li2ZrO3 coating prepared under either dry air or oxygen. The effect of the coating atmosphere on the electrochemical properties of Li2ZrO3/LiNi0.6Co0.2Mn0.2O2 are systematically investigated by multiple structural characterization (synchrotron HRXRD, SEM, TEM, and XPS) and electroanalytical (EIS, SSCV, and GITT) techniques. The Li2ZrO3 coating prepared in oxygen is largely amorphous. It not only provides surface protection against the electrolyte corrosion but also enables faster lithium-ion transport at the interfacial regions. Additionally, oxygen atmosphere facilitates Zr diffusion from the surface coating to the bulk of LiNi0.6Co0.2Mn0.2O2, which stabilizes the crystal structure and enhances lithium-ion diffusion. Consequently, LiNi0.6Co0.2Mn0.2O2 cathodes coated with Li2ZrO3 in oxygen exhibit improved high-voltage cycling stability and high-rate performance.

Transitioning from fossil fuels to renewable energy sources is a critical goal to address greenhouse gas emissions and climate change. Major improvements have made wind and solar power increasingly cost-competitive with fossil fuels. However, the inherent intermittency of renewable power sources motivates pairing these resources with energy storage. Electrochemical energy storage in batteries is widely used in many fields and increasingly for grid-level storage, but current battery technologies still fall short of performance, safety, and cost. This review focuses on sodium metal halide (Na-MH) batteries, such as the well-known Na-NiCl2 battery, as a promising solution to safe and economical grid-level energy storage. Important features of conventional Na-MH batteries are discussed, and recent literature on the development of intermediate-temperature, low-cost cathodes for Na-MH batteries is highlighted. By employing lower cost metal halides (e.g., FeCl2, and ZnCl2, etc.) in the cathode and operating at lower temperatures (e.g., 190 °C vs. 280 °C), new Na-MH batteries have the potential to offer comparable performance at much lower overall costs, providing an exciting alternative technology to enable widespread adoption of renewables-plus-storage for the grid.

The developments of all-solid-state sodium batteries are severely constrained by poor Na-ion transport across incompatible solid-solid interfaces. We demonstrate here a triple Na

We modify a nickel-rich layered LiNi0.8Co0.1Mn0.1O2 (NCM811) positive electrode material by substituting the transition metals with Zr to mitigate its structural instability and capacity degradation. We show that Zr, over a concentration range of 0.5–5.0 at.%, can simultaneously reside on and expand the lattice of NCM811 and form Li-rich lithium zirconates on their surfaces. In particular, Li(Ni0.8Co0.1Mn0.1)0.99Zr0.01O2 (1% Zr-NCM811) exhibits the best rate capability among all the compositions in this study. It shows higher cycling durability than the raw NCM811 at both low and high current density lithiation and de-lithiation. According to X-ray photoelectron spectroscopy and cyclic voltammetry measurements, the 1% Zr-NCM811 sample is more chemically/electrochemically stable than the raw. In addition to comparing the diffusivities in the coin-cell measurements, we demonstrate that Zr modification can facilitate Li-ion diffusion in the NCM811 balk material by direct-current polarization measurements. The superior performance of Zr-NCM811 results from the lattice expansion induced by Zr doping and the presence of ion-conducting lithium zirconates partially coated on the surface of Zr-NCM811 particles.

A major advantage of plug-in hybrid electric vehicles is their high fuel economy, which is closely related to their energy management strategy and driving cycles. In this study, an improved velocity prediction method is formulated based on the Markov model and a back propagation neural network. The root mean square error of the predicted velocity for the New European Driving Cycle is 0.1511 m/s when the prediction time is 3 s. Moreover, a vehicle test for the velocity prediction algorithm is implemented on a hybrid electric bus, which verifies the reliability and real-time performance. On this basis, a model predictive control-based energy management strategy incorporating the velocity prediction is proposed. In order to lessen the computation and memory burden and constrain the battery's state of charge, a state of charge-based adaptive equivalent consumption minimization strategy is applied to the predictive control-based energy management strategy. By simulation, the proposed velocity prediction-based energy management strategy improves fuel economy by 3.11% and 7.93% for a plug-in hybrid electric commercial vehicle in the New European Driving Cycle, while 2.96% and 11.02% in the Worldwide Harmonized Light Vehicles Test Procedures, when compared with the adaptive equivalent consumption minimization strategy and equivalent consumption minimization strategy, respectively.

Intra-city buses have become an effective way to alleviate urban traffic congestion. Developing the driving cycle for an intra-city hybrid electric bus is of great importance for energy economy and emissions performances tests, as well as control strategy optimization to enhance fuel economy and reduce emissions. In the construction of the bus driving cycle using the adapted regular method based on kinematic segments with fixed time-steps, the transition of partial kinematic segments leads to velocity fluctuation, which does not reflect the actual driving characteristics. This study initially collects driving data from a hybrid electric bus in Shanghai, and constructs its typical driving cycle by the k-means clustering method. Considering the characteristics of frequent stopping and repetition during the bus driving cycle, the bus-station-based driving cycle segment division method and the whole-trip-based bus driving cycle construction method are proposed. A typical hybrid electric bus driving cycle is then constructed using the proposed methods. Finally, the typical hybrid electric bus driving cycles developed by two methods are compared and analyzed. The 2-norm value of the characteristic parameter error vector is decreased from 0.249 for the typical hybrid electric bus driving cycle based on the adapted regular method to 0.163 for the improved method. It is shown that the whole-trip-based bus driving cycle construction method reflects the actual driving characteristics better, has lighter computation burden, and lays the foundation for the development of an adaptive control strategy for the hybrid electric bus as well as tests of its energy economy and emissions.

Garnet-type cubic Li7La3Zr2O12 exhibits one of the highest lithium-ion conductivity values amongst oxides (up to ∼2 mS cm−1 at room temperature). This compound has also emerged as a promising candidate for solid electrolytes in all-solid-state lithium batteries, due to its high ionic conductivity, good chemical stability against lithium metal, and wide electrochemical stability window. Defect chemistry of this class of materials, although less studied, is critical to the understanding of the nature of ionic conductivity and predicting the properties of grain boundaries and heterogeneous solid interfaces. In this study, the electrical properties of nominally undoped cubic Li7La3Zr2O12 are characterized as a function of temperature and pO2 using a suite of AC impedance and DC polarization techniques. The formation of ionic defects and defect pairs as well as their impact on the transport properties are discussed, and a Brouwer-type diagram is constructed.

In this paper, an energy management strategy based on logic threshold is proposed for a plug-in hybrid electric vehicle. The plug-in hybrid electric vehicle powertrain model is established using MATLAB/Simulink based on experimental tests of the power components, which is validated by the comparison with the verified simulation model which is built in the AVL Cruise. The influence of the driving torque demand decision on the fuel economy of plug-in hybrid electric vehicle is studied using a simulation. The optimization method for the driving torque demand decision, which refers to the relationship between the accelerator pedal opening and driving torque demand, from the perspective of fuel economy is formulated. The dynamically changing inertia weight particle swarm optimization is used to optimize the decision parameters. The simulation results show that the optimized driving torque demand decision can improve the PHEV fuel economy by 15.8% and 14.5% in the fuel economy test driving cycle of new European driving cycle and worldwide harmonized light vehicles test respectively, using the same rule-based energy management strategy. The proposed optimization method provides a theoretical guide for calibrating the parameters of driving torque demand decision to improve the fuel economy of the real plug-in hybrid electric vehicle.

Ceramic-polymer composite electrolytes (CPEs) are being explored to achieve both high ionic conductivity and mechanical flexibility. Here, we show that, by incorporating 10 wt % (3 vol %) mixed-sized fillers of Li

Developing battery systems that are inexpensive, enduring, and safe is essential for integrating renewable energy sources such as solar and wind power into the electricity grid and providing valuable grid services such as frequency regulation, peak shaving, and arbitrage. In this regard, Na-based batteries are promising candidates because they use naturally abundant sodium (Na) as the charge carrier, which can potentially reduce the materials cost and support multiple energy storage applications. Among various Na-based batteries developed to date, thorough investigations have been done on high-temperature (~300°C) Na-metal halide (Na-MH) batteries, which offer long cycle life and superior safety. In particular, the tubular sodium-nickel chloride (Na-NiCl2 or Zebra) battery has been commercialized and found wide application in the telecom and oil/gas industries. However, the high operating temperature and cost of the Zebra battery has hindered its further market penetration. Considering constraints of the Ni-based cell chemistry, it is highly desirable to develop an alternate cathode for Na-MH batteries towards next-generation energy storage applications. This pursuit, unsurprisingly, led us to the Fe/NaCl cathode. In this study, we present an advanced Na-FeCl2 battery with unprecedented high-rate performance and low cost for stationary energy storage applications. Operated at an extremely high current density of 33.3 mA/cm2 at 190°C, the cell can output 74% of its total capacity—a capacity retention double that of IT Na-NiCl2 cells. The origin of the high rate capability of Na-FeCl2 batteries was elucidated by means of comprehensive phase/structure analysis and electrochemical/electroanalytical characterizations. Moreover, Fe particle pulverization originating from liquid-phase reactions was determined to be the major source of capacity fading during long-term cycling. Accordingly, we designed a unique cathode with Ni additive, which delivered a high discharge specific energy density of over 295 Wh/kg for 200 cycles at C/5 with almost no capacity fading.

Developing battery systems that are inexpensive, enduring, and safe is essential for integrating renewable energy sources such as solar and wind power into the electricity grid and providing valuable grid services such as frequency regulation, peak shaving, and arbitrage. In this regard, Na-based batteries are promising candidates because they use naturally abundant sodium (Na) as the charge carrier, which can potentially reduce the materials cost and support multiple energy storage applications. Among various Na-based batteries developed to date, thorough investigations have been done on high-temperature (~300°C) Na-metal halide (Na-MH) batteries, which offer long cycle life and superior safety. In particular, the tubular sodium-nickel chloride (Na-NiCl2 or Zebra) battery has been commercialized and found wide application in the telecom and oil/gas industries. However, the high operating temperature and cost of the Zebra battery has hindered its further market penetration. Considering constraints of the Ni-based cell chemistry, it is highly desirable to develop an alternate cathode for Na-MH batteries towards next-generation energy storage applications. This pursuit, unsurprisingly, led us to the Fe/NaCl cathode. In this study, we present an advanced Na-FeCl2 battery with unprecedented high-rate performance and low cost for stationary energy storage applications. Operated at an extremely high current density of 33.3 mA/cm2 at 190°C, the cell can output 74% of its total capacity—a capacity retention double that of IT Na-NiCl2 cells. The origin of the high rate capability of Na-FeCl2 batteries was elucidated by means of comprehensive phase/structure analysis and electrochemical/electroanalytical characterizations. Moreover, Fe particle pulverization originating from liquid-phase reactions was determined to be the major source of capacity fading during long-term cycling. Accordingly, we designed a unique cathode with Ni additive, which delivered a high discharge specific energy density of over 295 Wh/kg for 200 cycles at C/5 with almost no capacity fading.

This work studied the formation and growth of solid electrolyte interphase (SEI) under the assumption that the formation of an SEI layer is associated with the nucleation and growth of disk-like islands at the interface between an active material and nonaqueous electrolyte solution (NES). The supersaturation of NES favors the nucleation of the islands via lowering the Gibbs free energy with the contribution of interfacial energy and mismatch strain enegy to the nucleation process. Using a modified Lifshitz-Slyozov-Wagner model, the growth of the disk-like islands is analyzed. Explicit kinetic estimation for the change of the density and mean dimension of the islands as well as the degree of supersaturation of NES with time is obtained. The degree of supersaturation at time t is found to be proportional to the square root of time.

Garnet-type cubic Li

Composite electrodes consisting of cathode particles and an ion-conducting phase can address the limited ion accessibility of the cathode in high-energy all-solid-state lithium batteries. In this Letter, we discuss the microstructure–conductivity relationship in an electronic–ionic composite with a focus on lithium ion conductivity. This study is the first step toward further understanding of electrochemical reactions in all solid multiphase systems.

The performance of power-split hybrid powertrain systems vary with its configuration due to the differences of the number of planetary gear (PG) set as well as the type, number and installation location of shift actuators (clutch or brake). The 2-PG scheme has some advantages over 1-PG and n-PG (n >=3) systems in terms of structure, performance, and control complexity of the system. The competitive advantages of 2-PG scheme depend on configuration design (analysis, evaluation and screening) and parameter optimization. In this article, systematic methods of configuration design, analysis, evaluation, and screening for 2-PG multimode power-split hybrid powertrain systems are proposed and all potential configurations of 2-PG, connection positions of power components, different number of actuators, and combinations of different operating modes have been taken into consideration. A stepwise optimization design method (DOE sampling with self-adaptive PSO algorithm) is also formulated to optimize the 2-PG system's characteristics parameters (the two ratios of ring gear to sun gear) and the ratio of main reducer. Finally, an efficient automatic development process and tool based on engineering constraints is designed to optimize the 2-PG system scheme and to achieve the excellent system performance.

Vehicle energy economy is affected by different driving styles of individual drivers. To improve energy economy of plug-in hybrid electric vehicles (PHEVs), it is of great importance to develop the driving style adaptive optimal control strategy. In fact, driving styles are often influenced and restricted by different driving cycles. Therefore, to recognize driving style more accurately, this paper decouples driving styles from driving cycles. Based on classification and identification of driving cycles, the accelerator pedal opening and its change rate in different driving cycles are analyzed and the fuzzy-logic recognizer is built to identify driving styles. Afterwards, the driving style adaptive optimal control strategy is realized by combining the recognized driving style with the equivalent consumption minimization strategy (ECMS) and adopting a hybrid particle swarm optimization-genetic algorithm (PSO-GA) to optimize the relationship between the driving style and the equivalence factor (EF). The effectiveness of proposed driving style adaptive control strategy is validated by real vehicle test, which indicates that, compared with the original ECMS, the proposed driving style recognition based adaptive optimal control strategy improves the energy economy by 3.69% in the New European Driving Cycle (NEDC). This adaptive optimal strategy provides guidance for incorporating driving style into PHEV energy management strategy to improve fuel economy.

Mechanical degradation caused by lithiation/delithiation-induced stress and large volume change is the primary cause of fast capacity fading of silicon (Si)-based electrodes. Although intensive efforts have been devoted to understanding electromechanically induced fractures of electrodes made of Si alone (e.g., Si particles, Si thin films, and Si wafers), the cracking behavior of Si/polymeric binders/carbon black composite electrodes is unclear and poorly understood. Here, we investigate, by in situ and ex situ techniques, the cracking behavior of Si composite electrodes made with different binders, including polyvinylidene fluoride (PVDF), sodium-alginate (SA), sodium-carboxymethyl cellulose (Na-CMC), and Nafion. We found that extensive cracks form during the 1st delithiation process, which periodically open and close during subsequent lithiation/delithiation cycles at the same locations in the Si composite electrodes made with SA, Na-CMC, and Nafion. In contrast, a significantly fewer number of cracks form in the Si/PVDF electrodes after electrochemical cycling. A possible mechanism is proposed to help understand the effects of binders on the cracking behavior (e.g., crack spacing and island size) of Si composite electrodes. We also suggest possible approaches, including reducing the electrode thickness, patterning electrodes, and using highly recoverable binders, to inhibit cracks and improve the mechanical integrity of Si composite electrodes.

Battery technologies continue gaining interests for large scale energy storage applications, because it is becoming more critical to couple renewable resources to the grid and yet to maintain the grid reliability and sustainability. In particular, sodium (Na) based battery technologies are suitable for this application due to its potential low materials cost from using earth abundant Na as the charge carrier and the prolonged cycle life. Among various Na based batteries, Na-sulfur (Na-S) and Na-metal halide (Na-MH, Na-NiCl2 or ZEBRA) have been extensively studied and deployed for practical applications. Although Na-S and Na-NiCl2 batteries share some common features such as molten sodium and beta-alumina solid electrolyte, Na-NiCl2 batteries can provide several advantages over Na-S batteries, including superior battery safety, high open-circuit voltage, lower operating temperature, and ease of assembly in the discharged state without using metallic sodium in the anode. In here, we extend our studies of cathode materials to other nickel (Ni) halide compounds beside NiCl2, which has been extensively investigated in the past. It is found that using different types of halide anions can alter the anion diffusion process and the overall charge transfer reaction. We will present detailed electrochemical characterizations, battery testing, and spectroscopic characterizations to reveal the anionic chemistry of Na-MH batteries, which is important to further improve battery performances at lower operating temperatures.

The microstructural and compositional evolution at the solid/aqueous solution interfaces are investigated to monitor the electrical properties of superionic conducting phosphates and the electrochemical failure of aqueous sodium-ion batteries.

Lithium zirconate (LZO) is an attractive material for many applications. For example, it has been extensively studied as a solid absorbent for reversible CO2 capture at elevated temperatures, as a ceramic breeder for nuclear reactors, and as a coating for high-capacity cathode materials in lithium ion batteries (LIBs). The Li+ transport is critical to the functionality of LZO in these applications. For CO2 adsorption, Li+ diffusion is a critical factor affecting both surface absorption and high-temperature CO2 desorption processes. For LIBs, LZO can provide fast migration pathways for Li+ at the electrolyte-electrode interface when it is used as a coating for electrodes. For nuclear fusion, the Li+ migration through vacant sites inside LZO grains is closely related to its performance in tritium (3H) release. Therefore, understanding the Li+ migration mechanism and, more importantly, enhancing Li+ transport in LZO is important to many applications. Control of dopant concentration is an effective way to tune the Li+ conductivity. However, the electrical conductivity of doped LZO and the relationship between defect chemistry and electrical conductivity in doped LZO have not been reported. In addition, the effect of oxygen concentration on Li+ diffusion has not been fully understood. Here, we study the defect chemistry and electrical properties of the undoped LZO and a series of cation-doped LZO samples. We establish a relationship between Li+ conductivities and doping-induced oxygen/Li nonstoichiometries. We demonstrate that the conductivity results can be understood by unveiling the critical role of oxygen vacancies in Li+ transport. An improved CO2 absorption performance of doped LZO materials will also be discussed.

Aqueous sodium-ion batteries may solve the cost and safety issues associated with the energy storage systems for the fluctuating supply of electricity based on solar and wind power. Compared to their lithium counterparts, aqueous sodium-ion batteries offer multiple advantages including more earth abundant sodium, cheaper electrode materials and electrolyte solutions as well as less costly manufacturing conditions. However, poor overall performance and low electrode utilization (much of the electrode material ends up being electrochemically inactive) are the main barriers implementing them in (micro)grid systems. Here we characterize the surface reactions on NASICON-type phosphate anode material and rationalize their close associations with capacity fading upon slow cycling of aqueous sodium-ion batteries. The surface reactions result in the formation of an electrically insulating surface layer causing the failure of electrochemical performance and the precipitation of surface particles that blocks the pores thereby leading to poor electrode utilization. These findings provide insight into new possibilities of improving the electrochemical performance of aqueous sodium-ion batteries by the design of protective layers through surface modifications that prevent the formation of insulating surface layers and insoluble precipitates.