Synthesis of the Ni₂P–Co Mott–Schottky Junction as an Electrocatalyst to Boost Sulfur Conversion Kinetics and Application in Separator Modification in Li-S Batteries

Abstract

To overcome the shuttling effect and sluggish conversion kinetics of polysulfides, a large number of catalysts have been designed for lithium−sulfur (Li−S) batteries. Herein, a Mott−Schottky junction catalyst composed of Co nanoparticles and Ni 2 P was designed to improve polysulfide kinetics. Our investigations reveal the rearrangement of charges at the Schottky junction interface and the construction of the built-in electric field are crucial for lowering the activation energy of the dissolved Li 2 S n reduction and Li 2 S nucleation reaction. Furthermore, a series of experimental and electrochemical tests were performed to demonstrate that the Schottky catalytic effect enhanced the synergistic catalytic effect. With a Ni 2 P−Co@CNT catalyst, the battery exhibits an initial specific capacity of 874 mAh g −1 at a rate of 4.0 C, and the decay rate per cycle is 0.049% in 700 cycles. Meanwhile, the battery shows 0.118% decay rate per cycle at 0.5 C in 100 cycles at a high sulfur loading of 10 mg cm −2 . The Schottky heterojunction structure proposed here has been shown to have a good catalytic effect on the reduction of Li 2 S n and nucleation of Li 2 S, which provides a profound guidance for efficient and rational catalyst design.

Co/CoS2 Heterojunction Embedded in N, S‐Doped Hollow Nanocage for Enhanced Polysulfides Conversion in High‐Performance Lithium–Sulfur Batteries

“…[24] Recently, Co atom doping method into the TMCs to construct heterojunction has gained an appreciation since the lower work function of Co atom could become an electron reservoir and build Mott-Schottky architecture, where the electronic state of d orbitals of the transition metal compound could be altered, thus manipulating the condition of anti-bonding state and bonding-state. The various Co-TMCs materials including Co-TiO 2 , [25] Co-VN, [26] Co-Ni 2 P, [27] and Co-CoSe [28] have reported the inner electron transfer would upshift the d-band center of TMCs, bringing about the reinforced binding ability for polysulfides. In terms of the interaction of LiPSs with the substrate, the adsorbates are readily prone to anchoring on the electron provider.…”

A strontium ferrite modified separator for adsorption and catalytic conversion of polysulfides for excellent lithium–sulfur batteries

“…[10][11][12] Unambiguously, functional modified separators offer significant advantages in terms of inhibiting polysulfide diffusion and avoiding complex synthesis, which is conducive to large-scale commercial production. [13][14][15] A variety of carbon materials [16][17][18] and polar materials [19][20][21][22] have been introduced for separator modification by virtue of their ability to efficiently trap and catalyze LiPSs during cycling. Carbon materials have good electrical conductivity and play a physical adsorption role for LiPSs.…”

Bifunctional Additive for Lithium–Sulfur Batteries Based on the Metal–Phthalocyanine Complex

“…Lithium–sulfur batteries (LSBs) are promising candidates for energy storage systems due to their superior theoretical specific capacity and energy density. − However, the following intractable challenges should be addressed for the successful realization of LSBs: (1) the shuttle effect originating from the dissolution and diffusion of long-chain polysulfides (Li 2 S 4 –Li 2 S 8 ) in ether-based electrolytes; − and (2) the sluggish redox kinetics and severe cathode passivation originating from insulating Li 2 S during the discharge reaction. ,, The shuttle effect from Li-based polysulfides (LiPS) leads to self-discharge, loss of active material, reduced coulomb efficiency, rapid capacity decay, and fast Li corrosion during cycling. − Moreover, the insulating products of the discharged Li 2 S result in sluggish redox kinetics, leading to severe cathode passivation and diminishing overall sulfur utilization. , …”