The insurmountable charge transfer impedance at the Li metal/solid polymer electrolytes(SPEs)interface at room temperature as well as the ascending risk of short circuits at the operating temperature higher than the m...The insurmountable charge transfer impedance at the Li metal/solid polymer electrolytes(SPEs)interface at room temperature as well as the ascending risk of short circuits at the operating temperature higher than the melting point,dominantly limits their applications in solid-state batteries(SSBs).Although the inorganic filler such as CeO_(2)nanoparticle content of composite solid polymer electrolytes(CSPEs)can significantly reduce the enormous charge transfer impedance at the Li metal/SPEs interface,we found that the required content of CeO_(2)nanoparticles in SPEs varies for achieving a decent interfacial charge transfer impedance and the bulk ionic conductivity in CSPEs.In this regard,a sandwich-type composited solid polymer electrolyte with a 10%CeO_(2)CSPEs interlayer sandwiched between two 50%CeO_(2)CSPEs thin layers(sandwiched CSPEs)is constructed to simultaneously achieve low charge transfer impedance and superior ionic conductivity at 30℃.The sandwiched CSPEs allow for stable cycling of Li plating and stripping for 1000 h with 129 mV polarized voltage at 0.1 mA cm^(-2)and 30℃.In addition,the LiFePO_(4)/Sandwiched CSPEs/Li cell also exhibits exceptional cycle performance at 30℃and even elevated120℃without short circuits.Constructing multi-layered CSPEs with optimized contents of the inorganic fillers can be an efficient method for developing all solid-state PEO-based batteries with high performance at a wide range of temperatures.展开更多
As promising energy storage systems,lithium-sulfur(Li-S)batteries have attracted significant attention because of their ultra-high energy densities.However,Li-S battery suffers problems related to the complex phase co...As promising energy storage systems,lithium-sulfur(Li-S)batteries have attracted significant attention because of their ultra-high energy densities.However,Li-S battery suffers problems related to the complex phase conversion that occurs during the charge-discharge process,particularly the deposition of solid Li2S from the liquid-phase polysulfides,which greatly limits its practical application.In this paper,edge-rich MoS2/C hollow microspheres(Edg-MoS2/C HMs)were designed and used to functionalize separator for Li-S battery,resulting in the uniform deposition of Li2S.The microspheres were fabricated through the facile hydrothermal treatment of MoO3-aniline nanowires and a subsequent carbonization process.The obtained Edg-MoS2/C HMs have a strong chemical absorption capability and high density of Li2S binding sites,and exhibit excellent electrocatalytic performance and can effectively hinder the polysulfide shuttle effect and guide the uniform nucleation and growth of Li2S.Furthermore,we demonstrate that the Edg-MoS2/C HMs can effectively regulate the deposition of Li2S and significantly improve the reversibility of the phase conversion of the active sulfur species,especially at high sulfur loadings and high C-rates.As a result,a cell containing a separator functionalized with Edg-MoS2/C HMs exhibited an initial discharge capacity of 935 mAh g-1 at 1.0 C and maintained a capacity of 494 mAh g-1 after 1000 cycles with a sulfur loading of 1.7 mg cm-2.Impressively,at a high sulfur loading of 6.1 mg cm-2 and high rate of 0.5 C,the cell still delivered a high reversible discharge capacity of 478 mAh g-1 after 300 cycles.This work provides fresh insights into energy storage systems related to complex phase conversions.展开更多
Li[NixCoyMn2]O2（0.6≤x≤0.8） cathode materials with a typical hexagonal α-NaFeO2 structure were prepared utilizing a co-precipitation method.It is found that the ratio of peak intensities of（003） to（104） observ...Li[NixCoyMn2]O2（0.6≤x≤0.8） cathode materials with a typical hexagonal α-NaFeO2 structure were prepared utilizing a co-precipitation method.It is found that the ratio of peak intensities of（003） to（104） observed from X-ray diffraction（XRD）increases with decreasing the Ni content or increasing the Co content.The scanning electron microscopy（SEM） images reveal that the small primary particles are agglomerated to form the secondary ones.As the Mn content increases,the primary and secondary particles become larger and the resulted particle size for the Li[Ni（0.6）Co（0.2）Mn（0.2）]O2 is uniformly distributed in the range of100-300 nm.Although the initial discharge capacity of the Li/Li[NixCoyMn2]O2 cells reduces with decreasing the Ni content,the cyclic performance and rate capability are improved with higher Mn or Co content.The Li[Ni（0.6）Co（0.2）Mn（0.2）]O2 can deliver excellent cyclability with a capacity retention of 97.1%after 50 cycles.展开更多
Li3V2-2/3xMnx（PO4）3（0≤x≤0.12） powders were synthesized by sol-gel method. The effect of Mn2＋-doping on the structure and electrochemical performances of Li3V2（PO4）3/C was characterized by XRD, SEM, XPS, galva...Li3V2-2/3xMnx（PO4）3（0≤x≤0.12） powders were synthesized by sol-gel method. The effect of Mn2＋-doping on the structure and electrochemical performances of Li3V2（PO4）3/C was characterized by XRD, SEM, XPS, galvanostatic charge /discharge and electrochemical impedance spectroscopy（EIS）. The XRD study shows that a small amount of Mn2＋-doped does not alter the structure of Li3V2（PO4）3/C materials, and all Mn2＋-doped samples are of pure single phase with a monoclinic structure （space group P21/n）. The XPS analysis indicates that valences state of V and Mn are ＋3 and ＋2 in Li3V1.94Mn0.09（PO4）3/C, respectively, and the citric acid in raw materials was decomposed into carbon during calcination, and residual carbon exists in Li3V1.94Mn0.09（PO4）/C. The results of electrochemical measurements show that Mn2＋-doping can improve the cyclic stability and rate performance of these cathode materials. The Li3V1.94Mn0.09（PO4）3/C cathode material shows the best cyclic stability and rate performance. For example, at the discharge current density of 40 mA/g, after 100 cycles, the discharge capacity of Li3V1.94Mn0.09（PO4）3/C declines from initial 158.8 mA·h/g to 120.5 mA·h/g with a capacity retention of 75.9%; however, that of the Mn-undoed sample declines from 164.2 mA·h/g to 72.6 mA·h/g with a capacity retention of 44.2%. When the discharge current is increased up to 1C, the intial discharge capacity of Li3V1.94Mn0.09（PO4）3/C still reaches 146.4 mA·h/g, and the discharge capacity maintains at 107.5 mA·h/g after 100 cycles. The EIS measurement indicates that Mn2＋-doping with a appropriate amount of Mn2＋ decreases the charge transfer resistance, which is favorable for the insertion/extraction of Li＋.展开更多
Nanosphere-like Li2FeSiO4/C was synthesized via a solution method using sucrose as carbon sources under a mild condition of time-saving and energy-saving, followed by sintering at high temperatures for crystallization...Nanosphere-like Li2FeSiO4/C was synthesized via a solution method using sucrose as carbon sources under a mild condition of time-saving and energy-saving, followed by sintering at high temperatures for crystallization. The amount of carbon in the composite is less than 10% （mass fraction）, and the X-ray diffraction result confirms that the sample is of pure single phase indexed with the orthorhombic Pmn21 space group. The particle size of the Li2FeSiO4/C synthesized at 700 °C for 9 h is very fine and spherical-like with a size of 200 nm. The electrochemical performance of this material, including reversible capacity, cycle number, and charge-discharge characteristics, were tested. The cell of this sample can deliver a discharge capacity of 166 mA-h/g at C/20 rate in the first three cycles. After 30 cycles, the capacity decreases to 158 mA-h/g, and the capacity retention is up to 95%. The results show that this method can prepare nanosphere-like Li2FeSiO4/C composite with good electrochemical performance.展开更多
基金supported by the National Key R&D Program of China(2021YFB2400400)the National Natural Science Foundation of China(Grant No.22379120,22179085)+5 种基金the Key Research and Development Plan of Shanxi Province(China,Grant No.2018ZDXM-GY-135,2021JLM-36)the National Natural Science Foundation of China(Grant No.22108218)the“Young Talent Support Plan”of Xi’an Jiaotong University(71211201010723)the Qinchuangyuan Innovative Talent Project(QCYRCXM-2022-137)the“Young Talent Support Plan”of Xi’an Jiaotong University(HG6J003)the“1000-Plan program”of Shaanxi Province。
文摘The insurmountable charge transfer impedance at the Li metal/solid polymer electrolytes(SPEs)interface at room temperature as well as the ascending risk of short circuits at the operating temperature higher than the melting point,dominantly limits their applications in solid-state batteries(SSBs).Although the inorganic filler such as CeO_(2)nanoparticle content of composite solid polymer electrolytes(CSPEs)can significantly reduce the enormous charge transfer impedance at the Li metal/SPEs interface,we found that the required content of CeO_(2)nanoparticles in SPEs varies for achieving a decent interfacial charge transfer impedance and the bulk ionic conductivity in CSPEs.In this regard,a sandwich-type composited solid polymer electrolyte with a 10%CeO_(2)CSPEs interlayer sandwiched between two 50%CeO_(2)CSPEs thin layers(sandwiched CSPEs)is constructed to simultaneously achieve low charge transfer impedance and superior ionic conductivity at 30℃.The sandwiched CSPEs allow for stable cycling of Li plating and stripping for 1000 h with 129 mV polarized voltage at 0.1 mA cm^(-2)and 30℃.In addition,the LiFePO_(4)/Sandwiched CSPEs/Li cell also exhibits exceptional cycle performance at 30℃and even elevated120℃without short circuits.Constructing multi-layered CSPEs with optimized contents of the inorganic fillers can be an efficient method for developing all solid-state PEO-based batteries with high performance at a wide range of temperatures.
基金financially supported by National Natural Science Foundation of China (No. 51672083)Program of Shanghai Academic/Technology Research Leader (18XD1401400)+3 种基金Basic Research Program of Shanghai (17JC1404702)Leading talents in Shanghai in 2018The 111 project (B14018)the Fundamental Research Funds for the Central Universities (222201718002)
文摘As promising energy storage systems,lithium-sulfur(Li-S)batteries have attracted significant attention because of their ultra-high energy densities.However,Li-S battery suffers problems related to the complex phase conversion that occurs during the charge-discharge process,particularly the deposition of solid Li2S from the liquid-phase polysulfides,which greatly limits its practical application.In this paper,edge-rich MoS2/C hollow microspheres(Edg-MoS2/C HMs)were designed and used to functionalize separator for Li-S battery,resulting in the uniform deposition of Li2S.The microspheres were fabricated through the facile hydrothermal treatment of MoO3-aniline nanowires and a subsequent carbonization process.The obtained Edg-MoS2/C HMs have a strong chemical absorption capability and high density of Li2S binding sites,and exhibit excellent electrocatalytic performance and can effectively hinder the polysulfide shuttle effect and guide the uniform nucleation and growth of Li2S.Furthermore,we demonstrate that the Edg-MoS2/C HMs can effectively regulate the deposition of Li2S and significantly improve the reversibility of the phase conversion of the active sulfur species,especially at high sulfur loadings and high C-rates.As a result,a cell containing a separator functionalized with Edg-MoS2/C HMs exhibited an initial discharge capacity of 935 mAh g-1 at 1.0 C and maintained a capacity of 494 mAh g-1 after 1000 cycles with a sulfur loading of 1.7 mg cm-2.Impressively,at a high sulfur loading of 6.1 mg cm-2 and high rate of 0.5 C,the cell still delivered a high reversible discharge capacity of 478 mAh g-1 after 300 cycles.This work provides fresh insights into energy storage systems related to complex phase conversions.
基金Project(21473258)supported by the National Natural Science Foundation of ChinaProject(13JJ1004)supported by the Distinguished Young Scientists of Hunan Province,ChinaProject(NCET-11-0513)supported by the New Century Excellent Talents in University,China
文摘Li[NixCoyMn2]O2（0.6≤x≤0.8） cathode materials with a typical hexagonal α-NaFeO2 structure were prepared utilizing a co-precipitation method.It is found that the ratio of peak intensities of（003） to（104） observed from X-ray diffraction（XRD）increases with decreasing the Ni content or increasing the Co content.The scanning electron microscopy（SEM） images reveal that the small primary particles are agglomerated to form the secondary ones.As the Mn content increases,the primary and secondary particles become larger and the resulted particle size for the Li[Ni（0.6）Co（0.2）Mn（0.2）]O2 is uniformly distributed in the range of100-300 nm.Although the initial discharge capacity of the Li/Li[NixCoyMn2]O2 cells reduces with decreasing the Ni content,the cyclic performance and rate capability are improved with higher Mn or Co content.The Li[Ni（0.6）Co（0.2）Mn（0.2）]O2 can deliver excellent cyclability with a capacity retention of 97.1%after 50 cycles.
基金Project (20771100) supported by the National Natural Science Foundation of China
文摘Li3V2-2/3xMnx（PO4）3（0≤x≤0.12） powders were synthesized by sol-gel method. The effect of Mn2＋-doping on the structure and electrochemical performances of Li3V2（PO4）3/C was characterized by XRD, SEM, XPS, galvanostatic charge /discharge and electrochemical impedance spectroscopy（EIS）. The XRD study shows that a small amount of Mn2＋-doped does not alter the structure of Li3V2（PO4）3/C materials, and all Mn2＋-doped samples are of pure single phase with a monoclinic structure （space group P21/n）. The XPS analysis indicates that valences state of V and Mn are ＋3 and ＋2 in Li3V1.94Mn0.09（PO4）3/C, respectively, and the citric acid in raw materials was decomposed into carbon during calcination, and residual carbon exists in Li3V1.94Mn0.09（PO4）/C. The results of electrochemical measurements show that Mn2＋-doping can improve the cyclic stability and rate performance of these cathode materials. The Li3V1.94Mn0.09（PO4）3/C cathode material shows the best cyclic stability and rate performance. For example, at the discharge current density of 40 mA/g, after 100 cycles, the discharge capacity of Li3V1.94Mn0.09（PO4）3/C declines from initial 158.8 mA·h/g to 120.5 mA·h/g with a capacity retention of 75.9%; however, that of the Mn-undoed sample declines from 164.2 mA·h/g to 72.6 mA·h/g with a capacity retention of 44.2%. When the discharge current is increased up to 1C, the intial discharge capacity of Li3V1.94Mn0.09（PO4）3/C still reaches 146.4 mA·h/g, and the discharge capacity maintains at 107.5 mA·h/g after 100 cycles. The EIS measurement indicates that Mn2＋-doping with a appropriate amount of Mn2＋ decreases the charge transfer resistance, which is favorable for the insertion/extraction of Li＋.
基金Project supported by Ministry of Education Key Laboratory of Synthetic and Natural Functional Molecular Chemistry, China Project (2010JK765) supported by the Education Department of Shaanxi Province, China
文摘Nanosphere-like Li2FeSiO4/C was synthesized via a solution method using sucrose as carbon sources under a mild condition of time-saving and energy-saving, followed by sintering at high temperatures for crystallization. The amount of carbon in the composite is less than 10% （mass fraction）, and the X-ray diffraction result confirms that the sample is of pure single phase indexed with the orthorhombic Pmn21 space group. The particle size of the Li2FeSiO4/C synthesized at 700 °C for 9 h is very fine and spherical-like with a size of 200 nm. The electrochemical performance of this material, including reversible capacity, cycle number, and charge-discharge characteristics, were tested. The cell of this sample can deliver a discharge capacity of 166 mA-h/g at C/20 rate in the first three cycles. After 30 cycles, the capacity decreases to 158 mA-h/g, and the capacity retention is up to 95%. The results show that this method can prepare nanosphere-like Li2FeSiO4/C composite with good electrochemical performance.
