ZnFe₂O₄–Ni₅P₄ Mott–Schottky Heterojunctions to Promote Kinetics for Advanced Li–S Batteries

Abstract

The practical progress of lithium−sulfur batteries is hindered by the serious shuttle effect and the slow oxidation− reduction kinetics of polysulfides. Herein, the ZnFe 2 O 4 −Ni 5 P 4 Mott−Schottky heterojunction material is prepared to address these issues. Benefitting from a self-generated built-in electric field, ZnFe 2 O 4 −Ni 5 P 4 as an efficient bidirectional catalysis regulates the charge distribution at the interface and accelerates electron transfer. Meanwhile, the synergy of the strong adsorption capacity derived from metal oxides and the outstanding catalytic performance that comes from metal phosphides strengthens the adsorption of polysulfides, reduces the energy barrier during the reaction, accelerates the conversion between sulfur species, and further accelerates the reaction kinetics. Hence, the cell with ZnFe 2 O 4 −Ni 5 P 4 / S harvests a high discharge capacity of 1132.4 mAh g −1 at 0.5C and displays a high Coulombic efficiency of 99.3% after 700 cycles. The ZnFe 2 O 4 −Ni 5 P 4 /S battery still maintains a capacity of 610.1 mAh g −1 with 84.4% capacity retention after 150 cycles at 0.1C under a high sulfur loading of 3.2 mg cm −2 . This work provides a favorable reference and advanced guidance for developing Mott− Schottky heterojunctions in lithium−sulfur batteries.

Understanding the Catalytic Kinetics of Polysulfide Redox Reactions on Transition Metal Compounds in Li–S Batteries

“…The active sites of transition metal catalysts usually have an affinity for polysulfides, which results in a large amount of Li 2 S accumulating and reducing the oxidation kinetics during charging. This can be remedied through, in addition to the common structure modulation, the construction of heterogeneous structures, which can also enhance the bidirectional redox kinetics of Li–S batteies. − In contrast to individual TMCs, the heterogeneous structures designed by interface engineering combine the advantages of different materials to create synergistic effects that result in good physicochemical properties. − Recently, an increasing number of researchers found that the heterostructures could accelerate charge transfer and promote the bidirectional sulfur reaction kinetics to significantly improve the electrochemical performance of Li–S batteries. − Table shows the electrochemical performance of heterostructures as the sulfur host/separator modifier in Li–S batteries.…”

One-dimensional confined p–n junction Co3S4/MoS2 interface nanorods significantly enhance polysulfide redox kinetics for Li–S batteries

“…15,16 Interface engineering can fully combine the advantages of both components, and the strong interactions between interfaces enable manipulation of the surface electronic structure and accelerate electron transfer, opening a way to enhance the intrinsic conductivity and electrocatalytic activity of semiconductors. 17,18 Indeed, studies have shown that coupling p-type semiconductors with n-type semiconductors to form p-n heterojunction as catalytic materials (p-Co 3 O 4 /n-TiO 2 -HPs, NiO-Co 9 S 8 /rGO) considerably improves the performance of LSBs, and theoretical and experimental results indicate that the formed built-in electric eld at the p-n heterojunction interface can greatly enhance the adsorption of LiPSs and reaction kinetics of polysulde reduction and Li 2 S oxidation. 19,20 Therefore, it is feasible to increase the electroactivity and conductivity of MoS 2 by reasonably constructing p-n heterojunctions.…”

Improving the Electrochemical Performance of Li–S Batteries via a MnCo2S4–CoS1.097 Heterostructure with a Hollow Structure and High Catalytic Activity

“…Yang et al prepared the TiO 2 –TiN heterostructure and loaded it onto graphene, and LiPSs can realize a rapid “adsorption–diffusion–transformation” process at the interface, which greatly restrained the shuttle effect and upgraded the cycle performance . More recently, many burgeoning heterostructures, such as CoS 2 –Fe 7 S 8 , WS 2 –WO 3 , Co 9 S 8 –MoS 2 , ZnS–FeS, Co 3 S 4 /MnS, ZnFe 2 O 4 –Ni 5 P 4 , and CoMoS 3 –CoS, have been advanced into Li–S batteries as sulfur hosts or intermediate layer materials. Therefore, a reasonable design of the heterostructure is expected to be the most useful route for solving the shuttle effect of Li–S batteries based on the combination of chemical adsorption and catalytic conversion.…”

“…WS 2 −WO 3 ,22 Co 9 S 8 −MoS 2 ,23 ZnS−FeS,24 Co 3 S 4 /MnS,25 ZnFe 2 O 4 −Ni 5 P 4 ,26 and CoMoS 3 − CoS,27 have been advanced into Li−S batteries as sulfur hosts or intermediate layer materials. Therefore, a reasonable design of the heterostructure is expected to be the most useful route for solving the shuttle effect of Li−S batteries based on the combination of chemical adsorption and catalytic conversion.…”