Chemical doping is an effective method to intrinsically modify the chemical and electronic property of graphene. We propose a novel approach to synthesize the nitrogen-doped graphene via thermal annealing graphene wit...Chemical doping is an effective method to intrinsically modify the chemical and electronic property of graphene. We propose a novel approach to synthesize the nitrogen-doped graphene via thermal annealing graphene with urea, in which the nitrogen source can be controllably released from the urea by varying the annealed temperature and time. The doped N content and the configuration N as well as the thermal stabilities are also evaluated with X-ray photoelectron spectroscopy and Raman spectra. Electrical measurements indi- cate that the conductivity of doped graphene can be well regulated with the N content. The method is expected to produce large scale and controllable N-doped graphene sheets for a variety of potential applications.展开更多
Through meticulous design, a Li-lacking Cr2O5 cathode is physically mixed with Li-rich Li（1.2）Ni（0.13）Co（0.13）Mn（0.54）O2（LNCM） cathode to form composite cathodes LNCM@x Cr2O5（x = 0, 0.1, 0.2, 0.3, 0.35, 0.4...Through meticulous design, a Li-lacking Cr2O5 cathode is physically mixed with Li-rich Li（1.2）Ni（0.13）Co（0.13）Mn（0.54）O2（LNCM） cathode to form composite cathodes LNCM@x Cr2O5（x = 0, 0.1, 0.2, 0.3, 0.35, 0.4, mass ratio） in order to make use of the excess lithium produced by the Li-rich component in the first charge-discharge process. The initial coulombic efficiency（ICE） of LNCM half-cell has been significantly increased from75.5%（x = 0） to 108.9%（x = 0.35）. A novel full-cell comprising LNCM@Cr2O5composite cathode and Li4Ti5O（12） anode has been developed. Such electrode accordance, i.e., LNCM@Cr2O5//Li4Ti5O（12）（＂L-cell＂）, shows a particularly high ICE of97.7%. The ＂L-cell＂ can transmit an outstanding reversible capacity up to 250 mA h g-1and has 94% capacity retention during 50 cycles. It also has superior rate capacities as high as122 and 94 mA h g-（-1）at 1.25 and 2.5 A g-（-1）current densities,which are even better in comparison of Li-rich//graphite fullcell（＂G-cell＂）. The high performance of ＂L-cell＂ benefiting from the well-designed coulombic efficiency accordance mechanism displays a great potential for fast charge-discharge applications in future high-energy lithium ion batteries.展开更多
文摘Chemical doping is an effective method to intrinsically modify the chemical and electronic property of graphene. We propose a novel approach to synthesize the nitrogen-doped graphene via thermal annealing graphene with urea, in which the nitrogen source can be controllably released from the urea by varying the annealed temperature and time. The doped N content and the configuration N as well as the thermal stabilities are also evaluated with X-ray photoelectron spectroscopy and Raman spectra. Electrical measurements indi- cate that the conductivity of doped graphene can be well regulated with the N content. The method is expected to produce large scale and controllable N-doped graphene sheets for a variety of potential applications.
基金supported by the National Natural Science Foundation of China(51577175)NSAF(U1630106)
文摘Through meticulous design, a Li-lacking Cr2O5 cathode is physically mixed with Li-rich Li（1.2）Ni（0.13）Co（0.13）Mn（0.54）O2（LNCM） cathode to form composite cathodes LNCM@x Cr2O5（x = 0, 0.1, 0.2, 0.3, 0.35, 0.4, mass ratio） in order to make use of the excess lithium produced by the Li-rich component in the first charge-discharge process. The initial coulombic efficiency（ICE） of LNCM half-cell has been significantly increased from75.5%（x = 0） to 108.9%（x = 0.35）. A novel full-cell comprising LNCM@Cr2O5composite cathode and Li4Ti5O（12） anode has been developed. Such electrode accordance, i.e., LNCM@Cr2O5//Li4Ti5O（12）（＂L-cell＂）, shows a particularly high ICE of97.7%. The ＂L-cell＂ can transmit an outstanding reversible capacity up to 250 mA h g-1and has 94% capacity retention during 50 cycles. It also has superior rate capacities as high as122 and 94 mA h g-（-1）at 1.25 and 2.5 A g-（-1）current densities,which are even better in comparison of Li-rich//graphite fullcell（＂G-cell＂）. The high performance of ＂L-cell＂ benefiting from the well-designed coulombic efficiency accordance mechanism displays a great potential for fast charge-discharge applications in future high-energy lithium ion batteries.
