Co3O4 hollow nanospheres doped with ZnCo2O4 via thermal vapor mechanism for fast lithium storage

Abstract

Binary metal oxides offer improved anode materials in lithium ion batteries owing to enhanced electrical conductivity but suffer from large volume expansion on lithiation. A novel route to hollow Co3O4 nanospheres doped with ZnCo2O4 is demonstrated that mitigates the expansion issue and shows excellent performance at high current densities. The synthetic route is based on the pyrolysis of binary metalorganic-frameworks (MOFs) with the controlled loss of zinc tuning the micro and nanostructure of the material through a thermal vapor mechanism. The optimal structures, that contain hollow Co3O4 spheres of ca. 50 nm diameter doped with ZnCo2O4, show a specific capacity of 890 mAh g-1 at a current rate of 0.1 A g-1 and show a similar specific capacity at 1 A g-1 after 120 cycles at high current densities. The kinetics of lithiation/delithiation changes from diffusion-controlled to a surface-controlled process by the nanosizing of the particles. The resultant faster ion diffusion and capacitive storage for lithium ions are responsible for the extraordinary high-rate performance of the hollow structures.

Synergistic Interactions of Different Electroactive Components for Superior Lithium Storage Performance

“…It was already confirmed that the durable cycle stability is present for ZSO@NiO NFs, reaching 1000 cycles without noticeable capacity drops (Figure c). Interestingly, ZSO@NiO@G NFs exhibited even higher reversible capacity than ZSO@NiO NFs and showed excellent cyclability even after 1600 cycles, which is the most excellent value (1161 mAh g –1 at a current density of 1000 mA g –1 ) among previously reported mixed transition metal oxide (stannates, molybdates, cobaltates, ferrites, and manganates) based electrodes (Figure d). − The in situ galvanostatic EIS results of the ZSO@NiO@G NFs further supported both the excellent rate capability and cycle stability (Figure ). Generally, R ct is dependent on the electrical conductivity of host materials, since conductive hosts can facilitate Li ion transport to overcome the potential barrier appearing at the electrolyte/active material interface .…”

Hierarchical Hollow Bimetal Oxide Microspheres Synthesized through a Recrystallization Mechanism for High‐Performance Lithium‐Ion Batteries

“…ZCO-0.5 has the smallest semicircle diameter compared with the others, indicating that it possesses a more stable surface film and faster charge transfer. [32] Meanwhile, Table S2 shows that ZCO-0.5 has a smaller Rct compared with ZCO-0, suggesting that the size of the nanoparticles and the synergism of the bimetals can simultaneously enhance conductivity. Nyquist plots of ZCO-0.5 with different cycle numbers were also tested and are shown in Figure 8c, and their fitting data are in Table S3.…”

“…This morphological evolution and phase structure transformation process are different from those of other works previously reported. [15,[32][33] Thus, we propose a growth process mechanism of aggregation-dissolution-in-situ recrystallization for conveniently understanding the formation of such microspheres. At the beginning of the reaction, the metal glycerol carbonate nanosheets are formed and then nucleated by oriented growth in order to achieve minimum interfacial energies.…”

Sn@C evolution from yolk-shell to core-shell in carbon nanofibers with suppressed degradation of lithium storage

“…The resultant matrix consists of cubes wrapped by the polymer shells and interconnected along the PAN fibers, as shown in Figure S2. The fibers obtained are then sintered in an Ar atmosphere at high temperatures to evaporate Zn via a thermal vapor mechanism 17 and pyrolyze PAN into conductive nitrogen-doped carbon (NC) 18 . Figure 1a indicate that the sample annealed at 800 o C for 2 h contains Sn (PDF No.…”