Layered structure oxides have emerged as highly promising cathode materials for lithium-ion batteries.In these cathode materials,volume variation related to anisotropic lattice strain during Li^(+)insertion/extraction...Layered structure oxides have emerged as highly promising cathode materials for lithium-ion batteries.In these cathode materials,volume variation related to anisotropic lattice strain during Li^(+)insertion/extraction,however,can induce critical structural instability and electrochemical degradation upon cycling.Despite extensive research efforts,solving the issues of lattice strain and mechanical fatigue remains a challenge.This perspective aims to establishthe"structure-property relationship"between the degradation mechanism of the layered oxide cathode due to lattice strain and the structural evolution during cycling.By addressing these issues,we aim to guide the improvement of electrochemical performance,thereby facilitating the widespread adoption of these materials in future high-energy density lithium-ion batteries.展开更多
P2-type layered Ni–Mn-based oxides are vital cathode materials for sodiumion batteries(SIBs)due to their high discharge capacity and working voltage.However,they suffer from the detrimental P2→O_(2) phase transition...P2-type layered Ni–Mn-based oxides are vital cathode materials for sodiumion batteries(SIBs)due to their high discharge capacity and working voltage.However,they suffer from the detrimental P2→O_(2) phase transition induced by the O^(2-)−O^(2-)−electrostatic repulsion upon high-voltage charge,which leads to rapid capacity fade.Herein,we construct a P2-type Ni–Mn-based layered oxide cathode with a core-shell structure(labeled as NM–Mg–CS).The P2-Na_(0.67)[Ni_(0.25)Mn_(0.75)]O_(2)(NM)core is enclosed by the robust P2-Na_(0.67)[Ni_(0.21)Mn_(0.71)Mg_(0.08)]O_(2)(NM–Mg)shell.The NM–Mg–CS exhibits the phase-transition-free character with mitigated volume change because the confinement effect of shell is conductive to inhibit the irreversible phase transition of the core material.As a result,it drives a high capacity retention of 81%after 1000 cycles at 5 C with an initial capacity of 78mA h/g.And the full cell with the NM–Mg–CS cathode and hard carbon anode delivers stable capacities over 250 cycles.The successful construction of the core-shell structure in P2-type layered oxides sheds light on the development of high-capacity and long-life cathode materials for SIBs.展开更多
Polycrystalline SrBi_(4)Ti_(3.975)Zr_(0.025)O_(15)(SBTZ)was prepared using solid-state reaction technique.SBTZ was characterized by X-ray diffraction(XRD)and scanning electron microscopy(SEM).XRD analysis indicated th...Polycrystalline SrBi_(4)Ti_(3.975)Zr_(0.025)O_(15)(SBTZ)was prepared using solid-state reaction technique.SBTZ was characterized by X-ray diffraction(XRD)and scanning electron microscopy(SEM).XRD analysis indicated the formation of a single-phase orthorhombic structure.Particle size was found using SEM.The dielectric,ferroelectric,piezoelectric,modulus and impedance spectroscopy studies on SBTZ were investigated in the frequency range 1Hz-1MHz from room temperature(RT)to 600℃.Piezoelectric charge and electromechanical coupling coefficients were calculated from resonance and anti-resonance frequencies.Impedance and modulus plots were used as tools to analyze the sample behavior as a function of frequency.Cole-Cole plots showed a non-Debye relaxation.Conductivity measurements were performed on SBTZ.展开更多
基金supported by the National Natural Science Foundation of China(no.52272241)the Zhejiang Provincial Natural Science Foundation of China under grant no.LR24E020001.
文摘Layered structure oxides have emerged as highly promising cathode materials for lithium-ion batteries.In these cathode materials,volume variation related to anisotropic lattice strain during Li^(+)insertion/extraction,however,can induce critical structural instability and electrochemical degradation upon cycling.Despite extensive research efforts,solving the issues of lattice strain and mechanical fatigue remains a challenge.This perspective aims to establishthe"structure-property relationship"between the degradation mechanism of the layered oxide cathode due to lattice strain and the structural evolution during cycling.By addressing these issues,we aim to guide the improvement of electrochemical performance,thereby facilitating the widespread adoption of these materials in future high-energy density lithium-ion batteries.
基金supported by the National Natural Science Foundation of China(Nos.22121005 and 52072186)Open Foundation of Shanghai Jiao Tong University Shaoxing Research Institute of Renewable Energy and Molecular Engineering(No.JDSX2023003)+1 种基金the National Key Research and Development Program of China(Nos.2022YFB2402200 and 2019YFA0705600)the Fundamental Research Funds for the Central Universities of China(Nos.63233017,63231002,and 63231198).
文摘P2-type layered Ni–Mn-based oxides are vital cathode materials for sodiumion batteries(SIBs)due to their high discharge capacity and working voltage.However,they suffer from the detrimental P2→O_(2) phase transition induced by the O^(2-)−O^(2-)−electrostatic repulsion upon high-voltage charge,which leads to rapid capacity fade.Herein,we construct a P2-type Ni–Mn-based layered oxide cathode with a core-shell structure(labeled as NM–Mg–CS).The P2-Na_(0.67)[Ni_(0.25)Mn_(0.75)]O_(2)(NM)core is enclosed by the robust P2-Na_(0.67)[Ni_(0.21)Mn_(0.71)Mg_(0.08)]O_(2)(NM–Mg)shell.The NM–Mg–CS exhibits the phase-transition-free character with mitigated volume change because the confinement effect of shell is conductive to inhibit the irreversible phase transition of the core material.As a result,it drives a high capacity retention of 81%after 1000 cycles at 5 C with an initial capacity of 78mA h/g.And the full cell with the NM–Mg–CS cathode and hard carbon anode delivers stable capacities over 250 cycles.The successful construction of the core-shell structure in P2-type layered oxides sheds light on the development of high-capacity and long-life cathode materials for SIBs.
文摘Polycrystalline SrBi_(4)Ti_(3.975)Zr_(0.025)O_(15)(SBTZ)was prepared using solid-state reaction technique.SBTZ was characterized by X-ray diffraction(XRD)and scanning electron microscopy(SEM).XRD analysis indicated the formation of a single-phase orthorhombic structure.Particle size was found using SEM.The dielectric,ferroelectric,piezoelectric,modulus and impedance spectroscopy studies on SBTZ were investigated in the frequency range 1Hz-1MHz from room temperature(RT)to 600℃.Piezoelectric charge and electromechanical coupling coefficients were calculated from resonance and anti-resonance frequencies.Impedance and modulus plots were used as tools to analyze the sample behavior as a function of frequency.Cole-Cole plots showed a non-Debye relaxation.Conductivity measurements were performed on SBTZ.
