Superassembly of Porous Fe_tet(NiFe)_octO Frameworks with Stable Octahedron and Multistage Structure for Superior Lithium–Oxygen Batteries

Abstract

applications, especially portable electronic equipment and electric vehicles. [1][2][3][4][5][6][7] Rechargeable aprotic Li-O 2 batteries (LOBs) stand out for extremely high theoretical energy density (3623 Wh kg −1 based on the mass of oxygen and lithium), which is approaching that of gasoline and considerably ten times higher than that of current Li-ion batteries (LIBs). [8][9][10][11][12][13][14] According to previous reports, the operation of LOBs experiences the reversible formation (oxygen reduction reaction during discharge, ORR) and decomposition (oxygen evolution reaction during charge, OER) of discharge product Li 2 O 2 by means of the electrochemical reaction 2Li + + 2e − + O 2 ↔ Li 2 O 2 (2.98 V vs Li/Li + ). [15] The reactions between oxygen and lithium usually induce complicated growth pathways of Li 2 O 2 depending on the operating current density, electrolyte and catalyst, [16][17][18][19][20] which in turn resulting in a different mechanism and morphology of discharge products. The solution nucleation and growth of Li 2 O 2 particles are supposed to occur at a low current density, low overpotential, as well as in high donor number (DN) electrolyte solvent, whereas the surface growth mechanism takes place under the opposite factors then leading to quasiamorphous films on the cathode surfaces. [16,[21][22][23] For practical application of LOBs Promising lithium-oxygen batteries (LOBs) with extra-high capacities have attracted increasing attention for use in future electric devices. However, the challenges facing this complicated battery system still limit their practical applications. These challenges mainly consist of inefficient product evolution and low-activity catalysts. In present work, a cation occupying, modified 3D-architecture NiFeO cubic spinel is constructed via superassembly strategy to achieve a high rate, stable electrocatalyst for LOBs. The octahedron predominant spinel provides a stable polycrystal structure and optimized electronic structure, which dominates the discharge/charge products evolution with multiformation kinetics of crystal Li 2 O 2 and Li 2−x O 2 at low and high rate conditions and energetically favors the mass transport between the electrode/electrolyte interface. Simultaneously, the porous NiFeO framework provides adequate spaces for Li 2 O 2 accommodation and complex channels for sufficient electrolyte, oxygen, and ion transportation, which dramatically alter the cathode catalysis for an unprecedented performance. As a consequence, a large specific capacity of 23413 mAh g −1 and an excellent cyclability of 193 cycles at a high current of 1000 mA g −1 , and 300 cycles at a current of 500 mA g −1 , are achieved. The present work provides intrinsic insights into designing high-performance metal oxide electrocatalysts for Li-O 2 batteries with fine-tuned electronic and frame structure.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.

MoSe2@CNT Core–Shell Nanostructures as Grain Promoters Featuring a Direct Li2O2 Formation/Decomposition Catalytic Capability in Lithium‐Oxygen Batteries

“…Normally, the intensity of Li 2 O 2 Bragg peaks only represents crystalline peroxide, which suggests that the amorphous Li 2 O 2 films on CNT preferentially form at higher current rates. [ 11,13 ] The amorphous peroxide film would predict a restriction on the total electrochemistry capacity and limited cell life span by premature surface passivation, resulting in poor battery performance. [ 11 ] Since the formation of amorphous Li 2 O 2 in the MoSe 2 @CNT electrode can be fully excluded, layered MoSe 2 has reduced or suppressed the formation of amorphous thin Li 2 O 2 film significantly, even under a high current rate, whereas promoting the formation of crystalline Li 2 O 2 products and leading to a long cycle life.…”

“…For a new strategy to investigate an efficient catalyst, grain‐refining agents were suggested as an effective approach to control the growth of nanosized Li 2 O 2 and prevent the formation of passivating Li 2 O 2 film, as the agglomeration of amorphous Li 2 O 2 film could lead to premature cell death much earlier than their particle counterparts. [ 13–15 ] This type of agent could act as a substrate or seed for heterogeneous nucleation of discharge products, promoting the formation of nanosized Li 2 O 2 grain. Noble metals such as RuO 2 [ 16,17 ] and Pd [ 18,19 ] can promote the generation of Li 2 O 2 nanocrystalline to form micrometer‐sized Li 2 O 2 products.…”

Experimental And Theoretical Characteristic Of Single Atom Co-N-C Catalyst For Li-O2 Batteries

“…To further identify the mechanism of electrochemical reaction, DEMS (Fig. 6) was applied to figure out the gas evolution during charge process [52,53] with a fixed specific capacity of 500 mAh g -1 at a current of 200 mA g -1 . The curves of O 2 , CO 2 and H 2 O were selected from the gas mixture.…”

Highly Efficient Nb2C MXene Cathode Catalyst with Uniform O‐Terminated Surface for Lithium–Oxygen Batteries

“…and DMSO decomposition reaction exceeding 4.35 V, thereby relatively high charge overpotential and the amassment of byproducts during cycles contribute to the cell deterioration. [3,13,59]…”

“…However, due to the superoxide radicals generated during the ORR/OER process, a large amount of side products (Li 2 CO 3 ) is produced, which contributes to the poor cycle stability. [3] Researchers have been working on the development of novel catalysts with high efficiency and their electrochemical reaction mechanisms to reduce by-products and improve cycle life and efficiency, such as precious metals (Pt, [4][5][6][7] Au, [8] Pd, [4] and Ru [9,10] ), metal oxides (CeO 2 , [11] RuO 2 , [12] NiFeO, [13] NiCo 2 O 4 , [14] etc. ), metal carbides/nitrides (TiC, [15] Mo 2 C, [16] CoN, [17] etc.).…”