Pressureless all-solid-state Na/S batteries with self-supporting Na_(5)YSi_(4)O_(12) scaffolds

The development of reliable and affordable all-solid-state sodium metal batteries(ASS-SMBs)requires suitable solid-state electrolytes with cost-efficient processing and stabilized electrode/electrolyte interfaces.Here,an integrated porous/dense/porous Na_(5)YSi_(4)O_(12)(NYS)trilayered scaffold is designed and fabricated by tape casting using aqueous slurries.In this template-based NYS scaffold,the dense layer in the middle serves as a separator and the porous layers on both sides accommodate the active materials with their volume changes during the charge/discharge processes,increasing the contact area and thus enhancing the utilization rate and homogenizing the current distribution.The Na/NYS/Na symmetric cells with the Pb-coated NYS scaffold exhibit significantly reduced interfacial impedance and superior critical current density of up to 3.0 mA cm^(-2)against Na metal owing to enhanced wettability.Furthermore,the assembled Na/NYS/S full cells operated without external pressure at room temperature showed a high initial discharge capacity of 970 mAh g^(-1)and good cycling stability with a capacity of 600 mAh g^(-1)after 150 cycles(based on the mass of sulfur).This approach paves the way for the realization of economical and practical ASS-SMBs from the perspective of ceramic manufacturing.

N-doped porous carbon nanofibers sheathed pumpkin-like Si/C composites as free-standing anodes for lithium-ion batteries

Dramatic capacity fading and poor rate performance are two main obstacles that severely hamper the widespread application of the Si anode owing to its large volume variation during cycling and low intrinsic electrical conductivity.To mitigate these issues,free-standing N-doped porous carbon nanofibers sheathed pumpkin-like Si/C composites(Si/C-ZIF-8/CNFs)are designed and synthesized by electrospinning and carbonization methods,which present greatly enhanced electrochemical properties for lithium-ion battery anodes.This particular structure alleviates the volume variation,promotes the formation of stable solid electrolyte interphase(SEI)film,and improves the electrical conductivity.As a result,the as-obtained free-standing Si/C-ZIF-8/CNFs electrode delivers a high reversible capacity of 945.5 mAh g^(-1) at 0.2 A g^(-1) with a capacity retention of 64% for 150 cycles,and exhibits a reversible capacity of 538.6 mA h g^(-1) at 0.5 A g^(-1) over 500 cycles.Moreover,the full cell composed of a freestanding Si/C-ZIF-8/CNFs anode and commercial LiNi_(1/3)Co_(1/3)Mn_(1/3)O_(2)(NCM)cathode shows a capacity of 63.4 mA h g^(-1) after 100 cycles at 0.2 C,which corresponds to a capacity retention of 60%.This rational design could provide a new path for the development of high-performance Si-based anodes.

Core-shell structured 1,4-benzoquinone@TiO_2 cathode for lithium batteries

Organic carbonyl compounds are considered as promising candidates for lithium batteries due to theirhigh capacity and environmental friendliness, However, they suffer from serious dissolution in the elec-trolyte, leading to fast capacity decay. Here we report core-shell structured 1,4-benzoquinone@titaniumdioxide （BQ@TiO2） composite as cathode for lithium batteries. The composite cathode can deliver a highdischarge capacity of 441.2 mA h/g at 50 mA/g and a high capacity retention of 80.7% after 100 cycles. Thegood cycling performance of BQ@TiO2 composite can be attributed to the suppressed dissolution of BQ,which results from the physical confinement effect of Ti02 shell and the strong interactions between BQand Ti02. Moreover, the combination of ex situ infrared spectra and density functional theory calculationsreveals that the active redox sites of BQ are carbonyl groups. This work provides an alternative way tomitigate the dissolution of small carbonyl compounds and thus enhance their cycling stability.

Collaborative manufacturing technologies of structure shape and surface integrity for complex thin-walled components of aero-engine:Status,challenge and tendency

Presently,the service performance of new-generation high-tech equipment is directly affected by the manufacturing quality of complex thin-walled components.A high-efficiency and quality manufacturing of these complex thin-walled components creates a bottleneck that needs to be solved urgently in machinery manufacturing.To address this problem,the collaborative manufacturing of structure shape and surface integrity has emerged as a new process that can shorten processing cycles,improve machining qualities,and reduce costs.This paper summarises the research status on the material removal mechanism,precision control of structure shape,machined surface integrity control and intelligent process control technology of complex thin-walled components.Numerous solutions and technical approaches are then put forward to solve the critical problems in the high-performance manufacturing of complex thin-wall components.The development status,challenge and tendency of collaborative manufacturing technologies in the high-efficiency and quality manufacturing of complex thin-wall components is also discussed.

Enhanced room-temperature Na^(+) ionic conductivity in Na_(4.92)Y_(0.92)Zr_(0.08)Si_(4)O_(12)

Developing cost-effective and reliable solid-state sodium batteries with superior performance is crucial for stationary energy storage.A key component in facilitating their application is a solid-state electrolyte with high conductivity and stability.Herein,we employed aliovalent cation substitution to enhance ionic conductivity while preserving the crystal structure.Optimized substitution of Y^(3+)with Zr^(4+)in Na_(5)YSi_(4)O_(12) introduced Naþion vacancies,resulting in high bulk and total conductivities of up to 6.5 and 3.3 mS cm^(-1),respectively,at room temperature with the composition Na_(4.92)Y_(0.92)Zr_(0.08)Si_(4)O_(12)(NYZS).NYZS shows exceptional electrochemical stability(up to 10 V vs.Naþ/Na),favorable interfacial compatibility with Na,and an excellent critical current density of 2.4 mA cm^(-2).The enhanced conductivity of Naþions in NYZS was elucidated using solid-state nuclear magnetic resonance techniques and theoretical simulations,revealing two migration routes facilitated by the synergistic effect of increased Naþion vacancies and improved chemical environment due to Zr^(4+)substitution.NYZS extends the list of suitable solid-state electrolytes and enables the facile synthesis of stable,low-cost Naþion silicate electrolytes.

Electrolyte solvation chemistry to construct an anion-tuned interphase for stable high-temperature lithium metal batteries

Lithium metal batteries are regarded as promising alternative next-generation energy storage systems.However,the unstable anode interphase results in dendrite growth and irreversible lithium consumption with low Coulombic efficiency(CE).Herein,we rationally design a Li^(+)coordination structure via electrolyte solvation chemistry.Nitrate anions are aggregated in the solvation sheath,even at low concentration in a solvent with moderate solvation ability,which promotes Li^(+)desolvation and constructs a nitrate anion-tuned interphase.Meanwhile,a high-donor-number solvent is introduced as an additive to strongly coordinate with Li^(+),which accelerates the ion-transfer kinetics and rate performance.This not only results in micro-sized lithium deposition and a high CE of 99.5%over 3500 h,but also enables superior anode stability even under 50%depth plating/stripping and with a lean electrolyte of 3 g Ah^(-1)at 50℃.A lithium-sulfur battery exhibits a prolonged lifespan of 2000 cycles with an average CE of 100%.A full battery using 1x excess lithium exhibits a high capacity near 1600 mAh g S^(-1)for 100 cycles without capacity loss.Moreover,a 0.55 Ah pouch cell delivers a reversible energy density of 423 Wh kg^(-1)based on these electrodes and electrolyte.

Thermo-economic analysis of a direct supercritical CO_(2) electric power generation system using geothermal heat

A comprehensive thermo-economic model combining a geothermal heat mining system and a direct supercritical CO_(2) turbine expansion electric power generation system was proposed in this paper.Assisted by this integrated model,thermo-economic and optimization analyses for the key design parameters of the whole system including the geothermal well pattern and operational conditions were performed to obtain a minimal levelized cost of electricity(LCOE).Specifically,in geothermal heat extraction simulation,an integrated wellbore-reservoir system model(T2Well/ECO_(2)N)was used to generate a database for creating a fast,predictive,and compatible geothermal heat mining model by employing a response surface methodology.A parametric study was conducted to demonstrate the impact of turbine discharge pressure,injection and production well distance,CO_(2) injection flowrate,CO_(2) injection temperature,and monitored production well bottom pressure on LCOE,system thermal efficiency,and capital cost.It was found that for a 100 MWe power plant,a minimal LCOE of$0.177/kWh was achieved for a 20-year steady operation without considering CO_(2) sequestration credit.In addition,when CO_(2) sequestration credit is$1.00/t,an LCOE breakeven point compared to a conventional geothermal power plant is achieved and a breakpoint for generating electric power generation at no cost was achieved for a sequestration credit of $2.05/t.

Extraction of selected rare earth elements from anthracite acid mine drainage using supercritical CO2 via coagulation and complexation

Rare earth elements(REEs)are valuable raw materials which are in great demand in modern high technology industries.Developing methods to produce/recover REEs from waste is significant to the national security of any developed country.This study was focused on investigating the use of supercritical CO2(sCO2)to extract REEs from anthracite acid mine drainage(AMD).Four different mine drainage water source locations at Blaschak Coal Corp.in Pennsylvania,USA were selected for sample collection.An extraction process was developed and demonstrated for two of those water sources containing the highest concentration of REEs.A method involving metal ion coagulation,their dissolution from the sludge into a concentrated aqueous HNO3 solution,complexation with organic ligands and sCO2 extraction was developed to recover REEs from AMD.Specifically,sodium aluminate(NaAlO2)was used as the coagulant to concentrate REEs from the AMD into a solid precipitate.Consequently,over 99%of the REEs in AMD is concentrated in the remaining sludge.During the coagulation process,the effects of pH and NaAlO2 concentration on REE precipitation were investigated.Fuming nitric acid(HNO3)was used to digest the pre-concentrated sludge and tributyl phosphate(TBP)was used to form REE/TBP/HNO3,a non-polar complex with selected REEs,specifically,cerium(Ce),lanthanum(La)and neodymium(Nd).HNO3 concentration and organic/aqueous phase ratio were considered as the variables to improve complexation efficiency.Dynamic extraction experiments using sCO2 and REE/TBP/HNO3 solutions were then conducted at optimal conditions of 60℃and 20 MPa.The overall REE extraction efficiencies are found to increase with the atomic number of the REE.As a result,the average overall REE extraction efficiencies of 41.8%,40.1%and 58.2%for Ce,La and Nd,respectively,are obtained.The potential improvements in the overall extraction efficiency are also discussed.

Clinical features and prognostic factors of primary intracranial malignant fibrous histiocytoma:A report of 8 cases and a literature review

Objective: Primary intracranial malignant fibrous histiocytoma(MFH) is rare. We describe the detailed clinical features of 8 cases and fully review the literature to evaluate several prognostic factors. Methods: Eight patients with pathologically confirmed primary intracranial MFH were retrospectively reviewed. We searched Pub Med for relevant articles with the term "intracranial malignant fibrous histiocytoma". Results: Of the 8 patients, 4 were men and 4 were women. Three patients had received previous radiotherapy. The age of the patients ranged from 19 to 69 years, with a median age of 48 years. Most tumors could be totally resected; and only 1 tumor was subtotally resected. Six patients received postoperative radiotherapy and 3 patients received postoperative chemotherapy. Most patients died within the first year after surgery; and only 1 patient was still alive on the date of the last follow-up. We reviewed the literature and included a total of 46 patients in the Kaplan-Meier survival analysis. Young patients(less than 30 years old) seemed to have a better prognosis and survival rate than older patients(more than 30 years old)(log-rank test, P = 0.008).However, sex(P = 0.675), extent of resection(P = 0.934), postoperative radiotherapy(P = 0.592), and postoperative chemotherapy(P = 0.424) did not affect patient prognosis.Conclusions: The prognosis of MFH is usually poor, and most patients die within the first year after surgery. Younger MFH patients(less than 30 years old) seem to have a better prognosis and improved survival compared to older patients.

Complete resection of cavernous malformations in the hypothalamus:A case report and review of the literature

Objective: Cavernous malformation(CM) originating from the hypothalamus is extremely rare and the deep location presents a challenge for its neurosurgical management. We report such a case to better understand its clinical features. Methods and Results: A 40-year-old male patient presented with impaired vision in the left eye. Magnetic resonance imaging(MRI) revealed a regularly shaped round lesion located in the suprasellar cistern, and a clinical diagnosis of hypothalamic CM was made. Complete microsurgical excision was performed via a right pterional craniotomy. The patient showed good recovery with no further visual acuity or field deficits postoperatively. No CM recurrence or rebleeding was seen on follow-up MRI scans performed over the course of two years. Conclusions: For patients with cavernous malformation in the hypothalamus, accurate preoperative diagnosis with complete surgical removal by an appropriate surgical approach can contribute to satisfactory outcomes.

Post-traumatic cerebrospinal fluid rhinorrhea associated with craniofacial fibrous dysplasia:Case report and literature review

Objective: Fibrous dysplasia(FD) is an unusual developmental abnormality of the skeleton. When facial and cranial bones are involved in FD, it is termed craniofacial fibrous dysplasia(CFD). Although several reports have reported that CFD has a tendency for spontaneous cerebrospinal fluid(CSF) leakage, there have been no related English-language case reports. We present the first case of post-traumatic CSF rhinorrhea associated with CFD. Methods: A 30-year-old man presented with CSF rhinorrhea after a mild head trauma. Computed tomography cisternogram located a defect in the posterior wall of the right frontal sinus. Imaging examination also showed the evident expansion of multiple skull bones, spinal scoliosis, and multiple local enlargements of ribs.Without café-au-lait cutaneous spots and endocrine abnormalities, polyostotic FD was diagnosed instead of Mc Cune-Albright syndrome(MAS). The patient underwent craniotomy fistula repair surgery. The excised bone was contoured to be thinner to increase the cranial cavity. The patient recovered well and CSF leakage did not recur.But during a nineteen-month follow up, sight in the patient's left eye was decreased.MAS was suspected. Unfortunately the patient refused to take the proposed decompression surgery and laboratory tests of serum hormones. Conclusions: CFD, if the wall of the paranasal sinus is involved and the cranial cavity is decreased, may increase the risk of CSF rhinorrhea after head trauma.Expectant management is recommended in asymptomatic CFD patients even in the presence of optic nerve compression. As MAS may cause more problems, it should be precluded before polyostotic FD is diagnosed.