Controlling of Ni-Based Composites in Salt Melt Synthesis with High Sodium-Ion Storage Performance

Abstract

Owing to its fascinating properties (such as high theoretical specific capacity and considerable conductivity), nickel sulfide (NiS) was investigated comprehensively as an anode material in sodium-ion batteries. However, they still suffered from volume expansion and sluggish kinetics, resulting in serious cycle capabilities. Herein, through controlling the kind of molten salts (Na 2 SO 4 , NaCl, and Na 2 CO 3 ) in salt melt synthesis (SMS), a series of NiS with an N, S-codoped carbon layer was successfully prepared, accompanied with different morphologies and structures (earthworm-like belts and triangular and spherical particles). Tailored by the ionic strength and viscosity of molten salts, the as-prepared samples displayed different crystallization behaviors, bringing about a difference in electrochemical performance. As earthworm-like NiS@C was explored as an anode material for SIBs, an initial capacity of 712.5 mAh g −1 at 0.5 A g −1 could be obtained, and it still kept 527.4 mAh g −1 after 100 cycles. Even at 2.0 A g −1 , a capacity of 508.6 mAh g −1 could be achieved. Meanwhile, with the assistance of detailed kinetic analysis, the rapid diffusion behaviors of Na + and redox reaction mechanisms of as-fabricated samples were proven for the enhanced electrochemical properties. Given this, this work is expected to provide a method for designing the morphology and structure of metal sulfides, while shedding light on the orientation of fabricating advanced electrode materials for SIBs.

Large‐Scale and Homogenized Strategies of Spent LiFePO4 Recycling: Reconstruction of Targeted Lattice

“…[ 21a ] In Figure S6a–e (Supporting Information), with the assistance of the Gaussian function, the Raman spectrum among the range of 1000—1800 cm −1 could be divided into two peaks as follows: D‐band (related to defects of sp 3 ) and G‐band (ascribing to the graphitic carbon). [ 22 ] As shown in Figure S6f (Supporting Information), the I D / I G ‐values of as‐recovered samples were in order of LFP‐500 (1.052) < LFP‐400 (1.137) < LFP‐300 (1.440) < LFP‐600 (1.761) < LFP‐700 (1.813), indicating the carbon layer of LFP‐500 possessed the highest degree of graphitization. For the LFP cathode, a larger degree of graphitization was beneficial to improve the conductivity and further contribute to the Li ions diffusion behaviors.…”

Engineering Phase to Reinforce Dielectric Polarization in Nickel Sulfide Heterostructure for Electromagnetic Wave Absorption

“…[ 24 ] The high‐resolution S 2p spectra of three NiS x samples are illustrated in Figure 3e, and the C─S bond peak at 164.3 eV is deconvoluted in each spectrum. [ 20b,25 ] Additionally, in the S 2p spectrum of NiS 2 , the signals of S 2 2− 2p 3/2 and S 2 2− 2p 1/2 are detected at 162.4 and 163.6 eV. [ 26 ] For NiS, two peaks can be assigned to S 2− 2p 3/2 and S 2− 2p 1/2 , located at 161.4 and 162.8 eV, respectively.…”