Lithium-oxygen (Li-O 2 ) batteries have become one of the most promising next-generation energy storage systems due to their high theoretical specific capacity. However, Li-O 2 batteries still face the problem of high charging voltage due to incomplete decomposition of discharge products. Here, a nitrogen-doped hollow spherical carbon composite containing Ni/Co nanoparticles was prepared by hydrothermal and pyrolysis strategies, and used as positive catalyst for Li-O 2 batteries to adjust the morphology of the discharge product. The porous hollow carbon sphere provides sufficient space for the storage of discharge products. Nitrogen-doped carbon nanospheres can change the local charge density, improve the electron transfer performance, and reduce the resistivity of carbon nanospheres. In addition, the abundant M-N x active groups enhance the affinity of the positive electrode to the reaction intermediates, thus regulating the morphology of the discharge product Li 2 O 2 . Benefiting from the above synergistic advantages, the electrochemical performance of the Li-O 2 battery including round-trip efficiency, discharge capacity, and cycling stability is greatly improved. Graphical Abstract
The development of Li-CO2/O2battery with high energy density and long-term stability is urgently needed to fulfill the carbon neutralization and pollution-free environment targets. The biomass-derived heteroatom-doped carbon catalyst with the combination of high-efficiency catalytic activity and sustainable supply is a promising cathode catalyst in Li-CO2/O2battery. Specifically, the unique morphology and mesopore structure can promote the transfer of CO2, O2, and Li+. Abundant channel pores can provide discharge products accommodation to the largest extent. Nitrogen dopant, the commonly recognized active sites in carbon, can improve the electron conductivity and accelerate the sluggish kinetic reaction. Therefore, utilizing the louts leaves as the precursor, we successfully prepare the cellular-like nitrogen-doped activated carbon nanosheets (N-CNs) through the appropriate pyrolysis carbonization method. The as-synthesized carbon nanosheets display a three-dimensional interconnecting pore structure and abundant N-dopant actives, which dramatically improve the electrochemical catalytic activity of N-CNs. The Li-CO2/O2battery with the N-CNs cathode delivers a high discharge capacity of 9825 mAh g−1, low overpotential of 1.21 V, and stable cycling performance of 95 cycles. Thus, we carry out a facile method for N-doped carbon nanosheets preparation derived from the cheap natural biomass, which can be the effective cathode catalyst for environmental-friendly Li-CO2/O2battery.Keywords:biomass-derived carbon;carbon nanosheets;nitrogen defects;cathode catalyst;Li-CO2/O2battery
Although lithium–oxygen batteries (LOBs) hold great promise as future energy storage systems, they are impeded by insulated discharge product Li 2 O 2 and sluggish oxygen reduction reaction/oxygen evolution revolution (ORR/OER) kinetics. The application of a highly efficient cathode catalyst determines the LOBs performance. The d-band modulation and catalytic kinetics promotion are important concept guidelines for the performance enhancement of cathode catalysts. In this work, the homogeneous in-plane distortion-derived synergistic catalytic capability of an Ag 2 Mo 2 O 7 catalyst with modulated d-band centers and promoted ORR/OER kinetics is demontrated. The uniform elongation of Ag─O bonds and compression of Mo─O bonds in (020) plane leads to d-band splitting and d-band center optimization and delivers improved adsorption behavior for high ORR/OER capability. Furthermore, the spatial and energy overlap of Ag d xz and O 2 anti-bonding π * orbitals facilitate electron injection during ORR process and reduce the energy barrier for charge transfer and O 2 desorption during OER process, accelerating the ORR/OER kinetics. As a result, the (020) plane-exposed Ag 2 Mo 2 O 7 cathode exhibits ultralong cycle stability of 817 cycles at 500 mA g −1 and large specific discharge/charge capacities of 15898/15180 mAh g −1 . This work provides facile concept guidance for optimizing catalytic capability through controlled lattice distortion in cathode catalysts for LOBs.
危险品化学品经营许可证（带存储）