Three-Dimensional Porous Nitrogen-Doped Carbon Nanosheet with Embedded Ni_xCo_3–xS₄ Nanocrystals for Advanced Lithium–Sulfur Batteries

Abstract

The shuttle effect of lithium polysulfides (Li2S n ) in electrolyte and the low conductivity of sulfur are the two key hindrances of lithium sulfur (Li–S) batteries. In order to address the two issues, we propose a three-dimensional porous nitrogen-doped carbon nanosheet with embedded Ni x Co3–x S4 nanocrystals derived from metal–organic frameworks for the durable-cathode host material in Li–S batteries. Experiments and density functional theory simulations show that the large porosity, robust N-doped carbon framework, and evenly embedded Ni x Co3–x S4 nanocrystals with high polarity act as strong “traps” for the immobilization of Li2S n , which leads to an effective suppressing of the shuttle effect and promotes efficient utilization of sulfur. The Ni x Co3–x S4/N-doped carbon hybrid material exhibits a high reversible capacity of 1122 mAh g–1 at a current density of 0.5 C after 100 cycles. Even at high areal sulfur loadings of 10 and 12 mg cm–2, the hybrid cathode materials can maintain good areal capacities of 7.2 and 7.6 mAh cm–2 after 100 cycles. The present study sheds light on the principles of the anchoring behaviors of Li2S n species on bimetallic sulfide hybrid materials and reveals an attractive route to design the highly desirable cathode materials for Li–S batteries.

MXene‐Derived TinO2n−1 Quantum Dots Distributed on Porous Carbon Nanosheets for Stable and Long‐Life Li–S Batteries: Enhanced Polysulfide Mediation via Defect Engineering

“…In the C 1s spectrum (Figure 2d), there are two peaks located at 284.8 and 285.5 eV, which are attributable to the CC and CO bonds of PCN, respectively. [ 31 ] In addition, the high intensity ratio of CC/CO implies that PCN is mainly involved in carbon atoms, which is helpful for improving the conductivity of PCN. In the Ti 2p spectrum (Figure 2e), the pair of prominent peaks centered at 457.4/463.1 eV is ascribed to the Ti 3+ O bonds in Ti 2 O 3 and Ti 3 O 5 .…”

Crystalline Multi‐Metallic Compounds as Host Materials in Cathode for Lithium–Sulfur Batteries

“…It has been proved that the Ni 2+ and Co 3+ sites on Ni x Co 3−x S 4 nanocrystals surface can act synergistically with N sites on N-doped carbon nanosheet in anchoring polysulfides. [91] Also, the diffusion barrier of Li + ions at the Ni x Co 3−x S 4 /N-doped graphene interface is much lower than pure Ni x Co 3−x S 4 surface, which means that combining with carbon materials gives composite an overall better reaction kinetics. The obtained composite demonstrates excellent cycle stability by an initial capacity of 1162 mA h g −1 and low capacity degradation of 0.14% per cycle in 400 cycles at 1C, proving the good anchoring effects of the Li 2 S n on the bimetallic polar materials.…”

High‐performance nanostructure Fe 2 O 3 synthesized via novel direct current electric arc method as sulfur‐wrapping matrix for lithium‐sulfur batteries

“…To solve these problems, many researchers propose developing high-performance matrix materials to immobilize sulfur onto its surface via physical and chemical adsorption, so as to inhibit the shuttle effect of polysulfide and improve the sulfur conductivity. [5][6][7][8][9] Right now, the main types of matrix materials include carbon, inorganic metal compounds, conductive polymers, etc. [10][11][12][13] Carbon materials due to their stable structure, abundant pore structure and high conductivity are taken the lead in applying to the sulfurwrapping matrix material for many years.…”

“…However, the practicability has been seriously affected because of sulfur insulativity, volumetric expansion and “shuttle effect” caused by the solution of polysulfides (Li 2 S n [n = 4‐8]) during the electrochemical process, which results in low actual specific capacity and rapid capacity loss. To solve these problems, many researchers propose developing high‐performance matrix materials to immobilize sulfur onto its surface via physical and chemical adsorption, so as to inhibit the shuttle effect of polysulfide and improve the sulfur conductivity 5‐9 . Right now, the main types of matrix materials include carbon, inorganic metal compounds, conductive polymers, etc 10‐13 .…”