Layered Double Hydroxide with Interlayer Quantum Dots and Laminate Defects for High‐Performance Supercapacitor

Abstract

AbstractOwing to the flexible adjustability of laminates, layered double hydroxides (LDHs) can achieve enhanced conductivity and capacitance. However, the regulation of interlayer activity is a great challenge because of the unconquerable charge repulsion between laminates. Herein, a dual‐activity design of LDHs is uniquely realized, including laminate defects and interlayer ZnS quantum dots (QDs). Via pre‐embedding Zn2+ and controllable vulcanization, ZnS‐QDs interpenetrate between CuCo‐LDH layers, exposing abundant active sites and widening the layer spacing. Meanwhile, sulfur replaces part of the oxygen on the laminates to form rich oxygen vacancies (CuCo‐LDH‐S), which does not damage the layered spatial structure and ensures the fast ions/electron transport. Theoretical calculations indicate that the new active centers exhibit higher charge density as compared to CuCo‐LDH. Moreover, the copper foam directly provides copper source to ensure that CuCo‐LDH‐S/ZnS‐QDs present a 3D self‐supporting structure with ultrastability. Hence, it delivers an ultrahigh capacitance of 7.82 F cm−2 at 2 mA cm−2 and 4.43 F cm−2 at 20 mA cm−2. The hybrid supercapacitors display an outstanding energy density of 299 µWh cm−2 at power density of 1600 µW cm−2, with outstanding capacitance retention of 102.3% and coulomb efficiency of 96.2% after 10 000 cycles.