Boosting the Pseudocapacitive and High Mass‐Loaded Lithium/Sodium Storage through Bonding Polyoxometalate Nanoparticles on MXene Nanosheets

Abstract

Achieving rate‐capable and high mass‐loaded lithium/sodium storage plays a pivotal role in promoting real world applications of many emerging electrode materials. Herein, such an electrode material is reported made of Mo and Fe‐based polyoxometalates firmly bonded on MXene nanosheets through a mild in situ growth procedure. The polyoxometalate nanoparticles can efficiently prevent the restacking of the MXene nanosheets, enabling an electrolyte‐permeable architecture at high mass loadings while the metallic conductivity of MXenes allows rapid electron transfer contributing to the full exploration of the rich redox capability of polyoxometalates even at high rates. The optimal structure delivers a high capacity of 297 and 191 mA h g–1 at 1.0 A g–1 for lithium and sodium storage, respectively, even after a thousand of cycles. The kinetic analysis suggests high capacitive contributions of 81.6% and 67.4% for lithium and sodium uptake/release at 1.0 mV s–1, respectively. Moreover, a decent capacity remains even after 13.5‐fold increase of loading mass. The lithium/sodium‐ion hybrid supercapacitors based on this composite deliver remarkable energy density and power capability. The results demonstrated in this work may offer an alternative selection of electrodes based on rationally designed polyoxometalates and MXenes.

MXene-mediated regulation of local electric field surrounding polyoxometalate nanoparticles for improved lithium storage

“…S5d), MXenes (Fig. S6c) and other related structures (Table S2) [53][54][55][56]. The local electrical field at the interface plays a crucial role in the boosted electrochemical performance where the larger difference in electrical conductivity between different components, the better [24,57,58].…”

“…Meanwhile, the potential range of the anode and cathode was simultaneously recorded using the three-electrode split cell (Fig. S13) [56,61]. As shown in Fig.…”

Rechargeable Mg-Ion Full Battery System with High Capacity and High Rate

“…Derived from the log i vs log v plots in different redox states (Figure c), the b value of peaks 1–4 is estimated to be 0.78, 0.61, 0.75, and 0.67, respectively, implying the combined nature of C1 and C2 for these peaks. To quantify the capacitive contribution, the current density ( i ) at a given voltage ( V ) can be divided into two parts, i.e., k 1 v corresponding to the capacitive-controlled contribution and k 2 v 1/2 corresponding to diffusive-controlled section, following eq : where v is the scan rate. Based on the plot in Figure b and eq , the contribution of pseudo-capacitive behavior in the capacity of the PTCDI anode ranging from 1.0 to 5.0 mV s –1 is plotted (Figure S4a–e).…”

In Situ Investigation of Expansion during the Lithiation of Pillared MXenes with Ultralarge Interlayer Distance

“…As observed in previous studies of MXenes in organic Li-ion systems, the capacitive contribution to the charge storage increased with the increasing scan rate (Supporting Information, Figure S4d). 32,33 Further details on this analysis are given in the Experimental Section in the Supporting Information. This analysis uses a range of sweep rates, similar to other reported studies on pillared MXenes in organic electrolytes.…”