CuO Nanoplates for High‐Performance Potassium‐Ion Batteries

Abstract

Potassium‐ion batteries (KIBs) are promising alternatives to lithium‐ion batteries because of the abundance and low cost of K. However, an important challenge faced by KIBs is the search for high‐capacity materials that can hold large‐diameter K ions. Herein, copper oxide (CuO) nanoplates are synthesized as high‐performance anode materials for KIBs. CuO nanoplates with a thickness of ≈20 nm afford a large electrode–electrolyte contact interface and short K+ ion diffusion distance. As a consequence, a reversible capacity of 342.5 mAh g−1 is delivered by the as‐prepared CuO nanoplate electrode at 0.2 A g−1. Even after 100 cycles at a high current density of 1.0 A g−1, the capacity of the electrode remains over 206 mAh g−1, which is among the best values for KIB anodes reported in the literature. Moreover, a conversion reaction occurs at the CuO anode. Cu nanoparticles form during the first potassiation process and reoxidize to Cu2O during the depotassiation process. Thereafter, the conversion reaction proceeds between the as‐formed Cu2O and Cu, yielding a reversible theoretical capacity of 374 mAh g−1. Considering their low cost, easy preparation, and environmental benignity, CuO nanoplates are promising KIB anode materials.

Boosting Coulombic Efficiency of Conversion‐Reaction Anodes for Potassium‐Ion Batteries via Confinement Effect

“…The components and valences of the CuS‐C@Nb 2 O 5 ‐C NFs were further evaluated by XPS after Ar etching for 30 s. As illustrated in Figure S7a in the Supporting Information, the wide XPS spectrum reveals the presence of Cu, S, Nb, O, N, and C, indicating that CuS and Nb 2 O 5 are included in the carbon nanofibers. In the high resolution XPS spectrum for Cu (Figure 3b), the two main peaks centered at 932.6 and 952.6 eV are attributed to Cu 2p3/2 and 2p1/2 of CuS, [ 15 ] while the faint peaks at 934.3 and 954.3 eV are ascribed to the Cu(II) from CuO, [ 25 ] which may be associated with the partial oxidation during preparation. In the S 2p XPS spectrum (Figure 3c), the defined peaks at 161.8 and 163.1 eV are assigned to 2p3/2 and 2p1/2 of S 2– in CuS, confirming the formation of CuS.…”

Polymer blend directed anisotropic self-assembly toward mesoporous inorganic bowls and nanosheets

“…Notably, bm-Nb 2 O 5 /C exhibits the highest rate capability among the previously reported metal oxide anodes ( fig. S20A and table S4) (46)(47)(48)(49)(50)(51)(52)(53)(54)(55)(56)(57). After galvanostatic cycles, the specific capacity could be recovered to 201 mA•hour g −1 when the current density was reset to 50 mA g −1 .…”

Face‐to‐Face Growth of Wafer‐Scale 2D Semiconducting MOF Films on Dielectric Substrates

“…[33] The high-resolution Cu 2p XPS spectrum showed two main peaks at ≈955 and 935 eV with a spin-orbital splitting separation of 20 eV which were attributed to Cu 2p1/2 and Cu 2p3/2, respectively ( Figure S25, Supporting Information). [34,35] The satellite peak located between 940 and 946 eV corresponded to electron-correlation effects of the 3d shell (3d 9 ) and indicated the formation of a Cu 2+ -based MOF thin film, and there were no other valence copper species as the 3d shells of copper for Cu (3d 10 4s 1 ) and Cu + (3d 10 ) are full. [36,37] The ≈1:1.9 elemental ratio between Cu and N confirmed a reasonable stoichiometry (Table S1, Supporting Information).…”