Manganese-based cathodes have gained significant attention for lithium-ion batteries(LIBs)due to their cost-effectiveness,safety,and environmental compatibility.Among them,LiMn_(2)O_(4)(LMO)is a promising candidate du...Manganese-based cathodes have gained significant attention for lithium-ion batteries(LIBs)due to their cost-effectiveness,safety,and environmental compatibility.Among them,LiMn_(2)O_(4)(LMO)is a promising candidate due to its high operating voltage(4.0 V)and three-dimensional lithium-ion transport pathways.However,its practical application is limited by Mn dissolution,induced by the disproportionation of Mn^(3+),leading to capacity fading and structural degradation.Surface coating strategies have been widely investigated to address this issue,with oxide coatings providing enhanced electrochemical stability while maintaining the intrinsic properties of LMO.Here,a Bi_(2)O_(3)-coated LiMn_(2)O_(4) hollow microsphere(BiLMOhms)was synthesized via a solution-based templated self-assembly method.This approach enables the formation of an ultrathin(2 nm)conformal Bi_(2)O_(3)coating,ensuring uniform coverage while preserving the LMO hollow structure.The Bi_(2)O_(3)layer improves the electrochemical performance by stabilizing the cathode–electrolyte interface,enhancing lithium-ion transport,and increasing the Mn^(4+)/Mn^(3+)ratio,thereby reducing Jahn–Teller distortion and suppressing Mn dissolution.Electrochemical characterization reveals that BiLMOhms exhibits superior cycling stability compared to pristine LMO.In half-cell tests,BiLMOhms retains 80.1% of its capacity after 1000 cycles,significantly higher than the 45.8%retention of pristine LMO.Moreover,in a full-cell configuration with a graphite anode,BiLMOhms achieves a capacity retention of 89.5% after 100 cycles at 1C,compared to 38.4%for pristine LMO.The coating effectively mitigates capacity degradation while facilitating ionic transport at the cathode–electrolyte interface.This study demonstrates a cost-effective and scalable synthesis strategy for stabilizing Mn-based cathodes in next-generation fast-charging LIBs.展开更多
Adolescent idiopathic scoliosis is a spinal deformity with unknown etiology and high incidence,especially in adolescent females.If scoliosis patients do not get effective treatment in the early stage,the degree of sco...Adolescent idiopathic scoliosis is a spinal deformity with unknown etiology and high incidence,especially in adolescent females.If scoliosis patients do not get effective treatment in the early stage,the degree of scoliosis will continue to worsen with the growth of age or the rapid development of scoliosis in a short time,and the appearance deformities such as high and low shoulders and razor back will gradually appear,which can affect the cardiopulmonary function and even shorten life expectancy.It has a great impact on the physical and mental health of the patients.Mild scoliosis is often well controlled by bracing,and moderate to severe scoliosis deformity often requires scoliosis corrective surgery.In adolescent idiopathic scoliosis correction,pedicle screws offer better stability and firmness,stronger orthopedic force,and lower incidence of related complications caused by instruments than traditional hook and conical internal fixation instruments.At the same time,scoliosis patients have uneven development of the left and right sides of the vertebral body,narrow diameter of concave pedicle and varying degrees of rotation of parietal vertebra,resulting in changes in the position of important anatomical structures such as spinal cord and thoracic aorta in the spinal canal.It makes it difficult to place pedicle screws,resulting in a high misplacement rate.How to improve the safety of screw placement,reduce the misplacement rate and the risk of spinal cord,nerve root,blood vessels,viscera and so on,has always been the focus of spinal surgeons.This paper summarizes the related literature on the effects of new techniques such as pedicle anatomy,complications of nail placement and computer navigation,and 3D guided template on the accuracy of screw placement in adolescent idiopathic scoliosis patients,and the safety of nail placement.In order to provide reference for clinical practice.展开更多
Modulating intrinsic activity and coupling with transition metal phosphides are encouraging strategies to enhance the electrochemical performance of carbon-based materials.In this study,N-doped carbon nanotubes were d...Modulating intrinsic activity and coupling with transition metal phosphides are encouraging strategies to enhance the electrochemical performance of carbon-based materials.In this study,N-doped carbon nanotubes were derived from polyaniline nanotubes by the guided growth of the soft template micelles comprising Fe^(3+)ions and methyl orange.Phytic acid was employed to detain Fe^(3+)ions from washing away so as to form iron phosphide(FeP and Fe2P)nanoparticles.NH3 plasma etching was further exerted for concurrent phase engineering of iron phosphide nanoparticles by transforming Fe2P to FeP,creating intrinsic carbon defects,as well as regulating the specific surface area and pore structure of the N-doped carbon nanotubes.It demonstrated that the phase transformation from Fe2P to FeP with higher crystallinity,together with the generated intrinsic carbon defects,played significant roles in promoting the oxygen reduction reaction(ORR)performance of the porous N-doped carbon nanotubes.As expected,the optimized composite(denoted as CV-FeP/NPCNT-30)revealed brilliant electrocatalytic ORR performance in 0.1 mol L^(-1) KOH aqueous solution,holding a more positive half-wave potential of 920 mV(vs.Reversible Hydrogen Electrode),a high diffusion limiting current density of 5.89 mA cm^(-2),delightful stability and methanol tolerance.Consequently,the liquid Zn-air battery(ZAB)established with CV-FeP/NPCNT-30 as the electrocatalyst in air-cathode manifested an outstanding power density(221 mW cm^(-2))and specific capacity(851.5 mA h g^(-1) Zn),outperforming the liquid ZABs based on the commercial Pt/C and some relevant electrocatalysts recently reported.展开更多
基金supported by the Research and Development Program of the Korea Institute of Energy Research(Grant No.C5-2408)the UST Young Scientist+Research Program 2023 through the University of Science and Technology(2023YS34)+1 种基金the National Research Council of Science&Technology(NST)grant by the Korean government(MSIT)(No.GTL24011-000)Synchrotron X-ray diffraction studies were carried out at the Pohang Accelerator Laboratory(Beamline 2D),with funding supported by MSIT and POSTECH.
文摘Manganese-based cathodes have gained significant attention for lithium-ion batteries(LIBs)due to their cost-effectiveness,safety,and environmental compatibility.Among them,LiMn_(2)O_(4)(LMO)is a promising candidate due to its high operating voltage(4.0 V)and three-dimensional lithium-ion transport pathways.However,its practical application is limited by Mn dissolution,induced by the disproportionation of Mn^(3+),leading to capacity fading and structural degradation.Surface coating strategies have been widely investigated to address this issue,with oxide coatings providing enhanced electrochemical stability while maintaining the intrinsic properties of LMO.Here,a Bi_(2)O_(3)-coated LiMn_(2)O_(4) hollow microsphere(BiLMOhms)was synthesized via a solution-based templated self-assembly method.This approach enables the formation of an ultrathin(2 nm)conformal Bi_(2)O_(3)coating,ensuring uniform coverage while preserving the LMO hollow structure.The Bi_(2)O_(3)layer improves the electrochemical performance by stabilizing the cathode–electrolyte interface,enhancing lithium-ion transport,and increasing the Mn^(4+)/Mn^(3+)ratio,thereby reducing Jahn–Teller distortion and suppressing Mn dissolution.Electrochemical characterization reveals that BiLMOhms exhibits superior cycling stability compared to pristine LMO.In half-cell tests,BiLMOhms retains 80.1% of its capacity after 1000 cycles,significantly higher than the 45.8%retention of pristine LMO.Moreover,in a full-cell configuration with a graphite anode,BiLMOhms achieves a capacity retention of 89.5% after 100 cycles at 1C,compared to 38.4%for pristine LMO.The coating effectively mitigates capacity degradation while facilitating ionic transport at the cathode–electrolyte interface.This study demonstrates a cost-effective and scalable synthesis strategy for stabilizing Mn-based cathodes in next-generation fast-charging LIBs.
基金This study was supported by Natural Science Foundation of Hainan Province(No.819QN365)National Natural Science Foundation of China(No.81902270)。
文摘Adolescent idiopathic scoliosis is a spinal deformity with unknown etiology and high incidence,especially in adolescent females.If scoliosis patients do not get effective treatment in the early stage,the degree of scoliosis will continue to worsen with the growth of age or the rapid development of scoliosis in a short time,and the appearance deformities such as high and low shoulders and razor back will gradually appear,which can affect the cardiopulmonary function and even shorten life expectancy.It has a great impact on the physical and mental health of the patients.Mild scoliosis is often well controlled by bracing,and moderate to severe scoliosis deformity often requires scoliosis corrective surgery.In adolescent idiopathic scoliosis correction,pedicle screws offer better stability and firmness,stronger orthopedic force,and lower incidence of related complications caused by instruments than traditional hook and conical internal fixation instruments.At the same time,scoliosis patients have uneven development of the left and right sides of the vertebral body,narrow diameter of concave pedicle and varying degrees of rotation of parietal vertebra,resulting in changes in the position of important anatomical structures such as spinal cord and thoracic aorta in the spinal canal.It makes it difficult to place pedicle screws,resulting in a high misplacement rate.How to improve the safety of screw placement,reduce the misplacement rate and the risk of spinal cord,nerve root,blood vessels,viscera and so on,has always been the focus of spinal surgeons.This paper summarizes the related literature on the effects of new techniques such as pedicle anatomy,complications of nail placement and computer navigation,and 3D guided template on the accuracy of screw placement in adolescent idiopathic scoliosis patients,and the safety of nail placement.In order to provide reference for clinical practice.
基金the financial support from the National Natural Science Foundation of China(No.51972109)the Natural Science Foundation of Hunan Province(No.2023JJ30276)the Scientific Research Funding of Hunan Provincial Education Department(No.22A0473 and 20A225).
文摘Modulating intrinsic activity and coupling with transition metal phosphides are encouraging strategies to enhance the electrochemical performance of carbon-based materials.In this study,N-doped carbon nanotubes were derived from polyaniline nanotubes by the guided growth of the soft template micelles comprising Fe^(3+)ions and methyl orange.Phytic acid was employed to detain Fe^(3+)ions from washing away so as to form iron phosphide(FeP and Fe2P)nanoparticles.NH3 plasma etching was further exerted for concurrent phase engineering of iron phosphide nanoparticles by transforming Fe2P to FeP,creating intrinsic carbon defects,as well as regulating the specific surface area and pore structure of the N-doped carbon nanotubes.It demonstrated that the phase transformation from Fe2P to FeP with higher crystallinity,together with the generated intrinsic carbon defects,played significant roles in promoting the oxygen reduction reaction(ORR)performance of the porous N-doped carbon nanotubes.As expected,the optimized composite(denoted as CV-FeP/NPCNT-30)revealed brilliant electrocatalytic ORR performance in 0.1 mol L^(-1) KOH aqueous solution,holding a more positive half-wave potential of 920 mV(vs.Reversible Hydrogen Electrode),a high diffusion limiting current density of 5.89 mA cm^(-2),delightful stability and methanol tolerance.Consequently,the liquid Zn-air battery(ZAB)established with CV-FeP/NPCNT-30 as the electrocatalyst in air-cathode manifested an outstanding power density(221 mW cm^(-2))and specific capacity(851.5 mA h g^(-1) Zn),outperforming the liquid ZABs based on the commercial Pt/C and some relevant electrocatalysts recently reported.
