A Lithium‐Ion Battery using a 3 D‐Array Nanostructured Graphene–Sulfur Cathode and a Silicon Oxide‐Based Anode

Abstract

An efficient lithium-ion battery was assembled by using an enhanced sulfur-based cathode and a silicon oxide-based anode and proposed as an innovative energy-storage system. The sulfur-carbon composite, which exploits graphene carbon with a 3 D array (3DG-S), was synthesized by a reduction step through a microwave-assisted solvothermal technique and was fully characterized in terms of structure and morphology, thereby revealing suitable features for lithium-cell application. Electrochemical tests of the 3DG-S electrode in a lithium half-cell indicated a capacity ranging from 1200 to 1000 mAh g at currents of C/10 and 1 C, respectively. Remarkably, the Li-alloyed anode, namely, Li SiO -C prepared by the sol-gel method and lithiated by surface treatment, showed suitable performance in a lithium half-cell by using an electrolyte designed for lithium-sulfur batteries. The Li SiO -C/3DG-S battery was found to exhibit very promising properties with a capacity of approximately 460 mAh g delivered at an average voltage of approximately 1.5 V over 200 cycles, suggesting that the characterized materials would be suitable candidates for low-cost and high-energy-storage applications.

Sulfur Loaded by Nanometric Tin as a New Electrode for High‐Performance Lithium/Sulfur Batteries

“…Instead, during the first anodic scan, the two oxidation peaks merge into a broad double peak, centered at about 2.4 and 2.45 V, by the conversion of the lithium polysulfides to the Li and S 8 species, as already observed previously for this kind of materials . The first CV cycle shows limited polarization and relevant reversibility, thus accounting for the fast kinetics of the electrochemical process compared with other electrodes, which further enhances during the subsequent cycles showing a shift of the cathodic peaks to higher potential values (2.35 and 2.05 V) and the anodic ones to lower values around 2.4 V. This suitable process, usually occurring from first to second cycle, is indicated in the literature by the term activation as it leads to an increased energy efficiency . This trend can be likely ascribed both to the formation of a stable solid electrolyte interphase (SEI) at the electrode surface by irreversible electrolyte degradation and to suitable modifications of the electrode structure during the first cycle leading to its gradual lithiation with partial formation of polysulfide and a decrease of the electrode/electrolyte interphase resistance .…”

Defect Control in the Synthesis of 2 D MoS2 Nanosheets: Polysulfide Trapping in Composite Sulfur Cathodes for Li–S Batteries

“…CV (Figure A–D) showed two distinct reduction peaks in the cathodic scan at approximately 2.0 and 2.4 V for all cells, which could be attributed to the formation of long‐chain (i.e., Li 2 S 8 , Li 2 S 6 , Li 2 S 4 ) and short‐chain (i.e., Li 2 S 2 , Li 2 S) PS, similar to previously reported peaks observed in ether‐based electrolyte . The oxidation process took place between 2.3 and 2.5 V, corresponding to the conversion of Li 2 S 2 or Li 2 S into soluble lithium PS and elemental sulfur . The two distinct oxidation peaks were noted in all cells, which have been reported previously only in some sulfur conductive matrix systems with high conductivity and low polarization .…”

“…[51] The oxidation process took place between 2.3 and 2.5 V, corresponding to the conversion of Li 2 S 2 or Li 2 Sintosoluble lithium PS and elemental sulfur. [65] The two distinct oxidation peaks were noted in all cells, whichh ave been reported previously only in some sulfur conductive matrix systems with high conductivity and low polarization. [66] The slight overpotential in the initial cathodic and anodics weep has previously been attributed to the polarization caused by the phase transition from the conversion-dissolution-diffusion process of the sulfur and PS.…”

The Role of Current Collector in Enabling the High Performance of Li/S Battery

“…Figure (a, b) shows the CV curves of 3DNG−S using Al and GDL support, respectively. Both samples show during cathodic scan the two typical reduction peaks at about 2.3 and 2 V, corresponding to the conversion of S 8 ring to long‐chain (Li 2 S x , 4 ≤ x < 8) and short chain (Li 2 S x , x =1,2) lithium polysulfides, which are reversed during anodic scan into merged peaks at potential higher than 2.2 V, by multiple step oxidation process of the polysulfides into sulfur . However, the cell using 3DNG−S cast into Al support (Figure a) shows a different reaction kinetics, peak broadening, higher polarization, and lower current intensity with respect to the same sulfur composite cast onto GDL (Figure b).…”

“…Very important factor influencing Li/S battery performance is the nature of the substrate used for the active material deposition, which actually improves the efficiency and the delivered capacity by the cell . Indeed, we have reported in previous works a variety of optimized sulfur composites benefitting of carbon nanotubes, and 3D‐graphene with improved performances in terms of delivered capacity, rate capability and stability, which were well promoted by the employment of a carbon paper, i. e., a gas diffusion layer (GDL), rather than conventional aluminum as the electrode support.…”