A novel Er:YAG laser system operating at 1645 nm with high pulse-repetition-frequency(PRF)of kHz level is demonstrated.A ring cavity with double gain medium end-pumped by two fiber lasers is utilized to obtain high pu...A novel Er:YAG laser system operating at 1645 nm with high pulse-repetition-frequency(PRF)of kHz level is demonstrated.A ring cavity with double gain medium end-pumped by two fiber lasers is utilized to obtain high pulse energy.A novel‘triple-reflection’configuration on a piezoelectric actuator(PZT)is adopted to achieve high-repetition-rate at 3-kHz operation with the ramp-fire locking method.Single frequency pulses with maximum average power of 18.3 W at 3 kHz are obtained,and the pulse duration time is 318 ns.The full line width at half maximum(FWHM)of the pulses measured by the heterodyne technique is 1.71 MHz at 3 kHz.To the best of our knowledge,this is the highest PRF single-frequency laser pulses achieved based Er:YAG gain medium.展开更多
金属锂具有高理论比容量和低氧化还原电位,被认为是高能量密度二次电池最理想的负极材料之一,但其在循环过程中的枝晶生长和体积变化易造成电池失效和安全隐患.以孔径为 5 μm 左右的自制三维多孔铜为基底,在其表面电沉积锌层(3D Cu@Zn)...金属锂具有高理论比容量和低氧化还原电位,被认为是高能量密度二次电池最理想的负极材料之一,但其在循环过程中的枝晶生长和体积变化易造成电池失效和安全隐患.以孔径为 5 μm 左右的自制三维多孔铜为基底,在其表面电沉积锌层(3D Cu@Zn),作为金属锂沉积的集流体,构筑无枝晶锂金属电极.三维多孔铜的孔结构稳定,孔径大小适宜,可有效降低局部电流密度和缓解体积变化.锌镀层可降低锂金属的形核过电位,诱导锂的均匀沉积,有效抑制锂枝晶生长.以 3D Cu@Zn 为集流体,锂沉积面积容量为 4 m Ah·cm^(-2),电极表面仍无枝晶出现,经过锂剥离后表面仍然光滑;而铜箔上沉积的锂显示明显的枝晶和不均匀性,3D Cu 上沉积的锂显示局部不均匀性和一定量枝晶.在电流密度为 0.5 和 1m A·cm^(-2),面积容量为 1 m Ah·cm^(-2)条件下,Li||3D Cu@Zn 半电池获得了稳定的库伦效率;在 2 m A·cm^(-2)的高电流密度和 1 m Ah·cm^(-2)的面积容量条件下,Li||3D Cu@Zn@Li 对称电池可稳定循环 700 h 以上;以 3D Cu@Zn@Li 为负极,Li Fe PO_(4)为正极的全电池,在 1 C 倍率下,经过 150 次循环后仍保持 88 m Ah·g^(-1)的容量,均明显优于 Cu 片和 3D Cu 作为集流体的锂金属电极.展开更多
基金the National Key Research and Development Program of China(Grant No.2017YFB0405203)the National Natural Science Foundation of China(Grant No.61627821).
文摘A novel Er:YAG laser system operating at 1645 nm with high pulse-repetition-frequency(PRF)of kHz level is demonstrated.A ring cavity with double gain medium end-pumped by two fiber lasers is utilized to obtain high pulse energy.A novel‘triple-reflection’configuration on a piezoelectric actuator(PZT)is adopted to achieve high-repetition-rate at 3-kHz operation with the ramp-fire locking method.Single frequency pulses with maximum average power of 18.3 W at 3 kHz are obtained,and the pulse duration time is 318 ns.The full line width at half maximum(FWHM)of the pulses measured by the heterodyne technique is 1.71 MHz at 3 kHz.To the best of our knowledge,this is the highest PRF single-frequency laser pulses achieved based Er:YAG gain medium.
文摘金属锂具有高理论比容量和低氧化还原电位,被认为是高能量密度二次电池最理想的负极材料之一,但其在循环过程中的枝晶生长和体积变化易造成电池失效和安全隐患.以孔径为 5 μm 左右的自制三维多孔铜为基底,在其表面电沉积锌层(3D Cu@Zn),作为金属锂沉积的集流体,构筑无枝晶锂金属电极.三维多孔铜的孔结构稳定,孔径大小适宜,可有效降低局部电流密度和缓解体积变化.锌镀层可降低锂金属的形核过电位,诱导锂的均匀沉积,有效抑制锂枝晶生长.以 3D Cu@Zn 为集流体,锂沉积面积容量为 4 m Ah·cm^(-2),电极表面仍无枝晶出现,经过锂剥离后表面仍然光滑;而铜箔上沉积的锂显示明显的枝晶和不均匀性,3D Cu 上沉积的锂显示局部不均匀性和一定量枝晶.在电流密度为 0.5 和 1m A·cm^(-2),面积容量为 1 m Ah·cm^(-2)条件下,Li||3D Cu@Zn 半电池获得了稳定的库伦效率;在 2 m A·cm^(-2)的高电流密度和 1 m Ah·cm^(-2)的面积容量条件下,Li||3D Cu@Zn@Li 对称电池可稳定循环 700 h 以上;以 3D Cu@Zn@Li 为负极,Li Fe PO_(4)为正极的全电池,在 1 C 倍率下,经过 150 次循环后仍保持 88 m Ah·g^(-1)的容量,均明显优于 Cu 片和 3D Cu 作为集流体的锂金属电极.
