Realization of High Energy Density Sodium-Ion Hybrid Capacitors through Interface Engineering of Pseudocapacitive 3D-CoO-NrGO Hybrid Anodes

Abstract

Sodium-ion hybrid capacitors (SHCs) have attracted great attention owing to the improved power density and cycling stability in comparison with sodium-ion batteries. Nevertheless, the energy density (<100 Wh·kg–1) is usually limited by low specific capacity anodes (<150 mAh·g–1) and “kinetics mismatch” between the electrodes. Hence, we report a high energy density (153 Wh·kg–1) SHC based on a highly pseudocapacitive interface-engineered 3D-CoO-NrGO anode. This high-performance anode (445 mAh·g–1 @0.025 A·g–1, 135 mAh·g–1 @5.0 A·g–1) consists of CoO (∼6 nm) nanoparticles chemically bonded to the NrGO network through Co–O–C bonds. Exceptional pseudocapacitive charge storage (up to ∼81%) and capacity retention (∼80% after 5000 cycles) are also identified for this SHC. Excellent performance of the 3D-CoO-NrGO anode and SHC is owing to the synergistic effect of the CoO conversion reaction and pseudocapacitive sodium-ion storage induced by numerous Na2O/Co/NrGO nanointerfaces. Co–O–C bonds and the 3D microstructure facilitating efficient strain relaxation and charge-transfer correspondingly are also identified as vital factors accountable for the excellent electrochemical performance. The interface-engineering strategy demonstrated provides opportunities to design high-performance transition metal oxide-based anodes for advanced SHCs.

Microwave‐Assisted Rational Designed CNT‐Mn3O4/CoWO4 Hybrid Nanocomposites for High Performance Battery‐Supercapacitor Hybrid Device

“…in CNT-Mn 3 O 4 /CoWO 4 confirmed its stronger pseudocapacitive energy storage characteristics. [37] Moreover, the longer discharge time and wider potential range of CNT-Mn 3 O 4 /CoWO 4 , further indicated its much larger storage capacity and higher energy density, which was consistent with the CV results. Based on Equations S2 and S3 (Supporting Information), the calculated specific capacities at various current densities were displayed in Figure 6c.…”

“…Similar to the CNT‐Mn 3 O 4 electrode, when the CNT‐Mn 3 O 4 /CoWO 4 ternary composite electrode was charged to 0.6 V and fully charged to 0.95 V, the interfacial chemical bonds of MnOC and CoOC were well preserved and the content remained stable, which implying that the existing heterocovalent bonds did not directly undergo conversion reactions to contribute additional capacity. [ 37 ] In contrast, in the process of charging to 0.6 and 0.95 V, the changes of MO and oxygen vacancy fitting peak intensity can be clearly observed. Specifically, when charging from 0.6 to 0.95 V, the MO band signal was obviously enhanced, while the deficient oxygen peak almost disappeared.…”

Pressure‐Stabilized High‐Entropy (FeCoNiCuRu)S2 Sulfide Anode toward Simultaneously Fast and Durable Lithium/Sodium Ion Storage

“…With respect to SICs, the HES//AC‐Na achieves a maximum energy density of 155.2 Wh kg −1 at 97.5 W kg −1 and achieves 43.9 Wh kg −1 even at the maximum power density of 58.5 kW kg −1 (Figure 4c). The excellent performance of our SICs surpasses that of previously reported SICs of OMC||N‐OMC, [ 63 ] CoO‐NrGO//AC, [ 64 ] AC//V 2 O 3 @MCNFs, [ 65 ] A‐TiO 2‐x ‐S/C‐2//NHPAC, [ 66 ] M‐TiO 2 @rGO//HPAC, [ 67 ] Ti 3 C 2 T x /Na 3 TCM//AC, [ 68 ] DR‐MoSe 2 //AC, [ 69 ] TiS 2 @C pvp //AC, [ 70 ] NiS x @PCM//AC SIHC, [ 71 ] CNF@VS 2 //CNF@GS. [ 72 ] Furthermore, as shown in Figure 4e and Figure S31f (Supporting Information), a higher capacity retention of 93.4% is attained by our HES//AC‐Na after 15 000 cycles at the high current density of 5 A g −1 , indicating its long‐term cyclic performance.…”

A comprehensive overview of MXene‐based anode materials for univalent metal ions (Li+, Na+, and K+) and bivalent zinc ion capacitor application

“…[57] The energy density of MICs is governed by the specific capacity and potential window of the device. [58,59] As far as cathode is concerned, the upper potential is restricted due to the electrolyte decomposition. Therefore, anode material with a high capacity and a low potential can be employed to achieve a high energy density of the MICs.…”

“…Moreover, the graphene/soft carbon assembly in a LIC punch cell shows the energy density as high as 31.5 Wh kg −1 and 93.8 % retention in capacity after 10,000 cycles at 50 C. A solid‐state ZIC assembled by employing Zn foil anode and bamboo shavings biomass derived porous carbon (S BET : 1442 m 2 g −1 ) cathode exhibits a high specific capacity (124 mAh g −1 @ 0.1 A g −1 ), a high power density (15221.2 W kg −1 ), a remarkable energy density (197.7 Wh kg −1 ), and an excellent cycling stability (94.73 % capacitance retention after 5000 cycles) [57] . The energy density of MICs is governed by the specific capacity and potential window of the device [58,59] . As far as cathode is concerned, the upper potential is restricted due to the electrolyte decomposition.…”