Cross-Linking Hollow Carbon Sheet Encapsulated CuP₂ Nanocomposites for High Energy Density Sodium-Ion Batteries

Abstract

Sodium-ion batteries (SIB) are regarded as the most promising competitors to lithium-ion batteries in spite of expected electrochemical disadvantages. Here a "cross-linking" strategy is proposed to mitigate the typical SIB problems. We present a SIB full battery that exhibits a working potential of 3.3 V and an energy density of 180 Wh kg with good cycle life. The anode is composed of cross-linking hollow carbon sheet encapsulated CuP nanoparticles (CHCS-CuP) and a cathode of carbon coated NaV(PO)F (C-NVPF). For the preparation of the CHCS-CuP nanocomposites, we develop an in situ phosphorization approach, which is superior to mechanical mixing. Such CHCS-CuP nanocomposites deliver a high reversible capacity of 451 mAh g at 80 mA g, showing an excellent capacity retention ratio of 91% in 200 cycles together with good rate capability and stable cycling performance. Post mortem analysis reveals that the cross-linking hollow carbon sheet structure as well as the initially formed SEI layers are well preserved. Moreover, the inner electrochemical resistances do not significantly change. We believe that the presented battery system provides significant progress regarding practical application of SIB.

Synthesis of Cobalt Sulfide Multi‐shelled Nanoboxes with Precisely Controlled Two to Five Shells for Sodium‐Ion Batteries

“…[9,[14][15][16][17][18] In particular,h ollow structures with complex interiors have drawn significant attention owing to their structure-dependent merits.A sf or sodium storage applications,i ntricate hollow structures exhibit great advantages over simple hollow architectures. [16,[19][20][21] Complex hollow particles not only inherit all the advantages of hollow structures,i ncluding high surface area, enhanced volume change accommodation and large electrode/electrolyte interface,b ut also improve the weight fraction of active species,thus dramatically enhancing the energy density of the electrode materials. [22] As ar esult, av ariety of electrode materials have been fabricated in the form of multi-shelled hollow structures.…”

Low‐Temperature Synthesis of Honeycomb CuP2@C in Molten ZnCl2 Salt for High‐Performance Lithium Ion Batteries

“…Them ixture is sealed in as tainless-steel autoclave and heated at 300 8 8Cfor 40 h. After cooling down to room temperature,t he mixture is washed by ethanol, hydrochloric acid, and deionized water to remove the inorganic salts.T he XRD pattern ( Figure 1i)s uggests the product consists of monoclinic CuP 2 phase (JCPDS 76-1190) without other impurities. [7] Thee nergy-dispersive spectrum (EDS) further confirms the Cu/P ratio is about 1:2(Supporting Information, Figure S3). Thecarbon content of CuP 2 @C is about 28 wt %, but mainly in amorphous state,assuggested by Raman spectrum (Supporting Information, Figure S4 Figure 1a shows the schematic structure of the honeycomb-like CuP 2 @C. X-ray photoelectron spectroscopy (XPS) is used to investigate the surface states of CuP 2 @C.A ss hown in the Supporting Information, Figure S5a, the Cu binding energy is 933.0 eV,which is in agreement with the reported XPS spectra of CuP 2…”

Synthesis of Cobalt Sulfide Multi‐shelled Nanoboxes with Precisely Controlled Two to Five Shells for Sodium‐Ion Batteries

“…In particular, hollow structures with complex interiors have drawn significant attention owing to their structure‐dependent merits. As for sodium storage applications, intricate hollow structures exhibit great advantages over simple hollow architectures . Complex hollow particles not only inherit all the advantages of hollow structures, including high surface area, enhanced volume change accommodation and large electrode/electrolyte interface, but also improve the weight fraction of active species, thus dramatically enhancing the energy density of the electrode materials .…”