Fast charging sodium-ion batteries based on Te-P-C composites and insights to low-frequency limits of four common equivalent impedance circuits

2021

Nanomaterials

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Metallic phase 1T MoS2 is a well-known potential anode for enhancing the electrochemical performance of lithium-ion batteries owing to its mechanical/chemical stability and high conductivity. However, during the lithiation/delithiation process, MoS2 nanosheets (NSs) tend to restack to form bulky structures that deteriorate the cycling performance of bare MoS2 anodes. In this study, we prepared Ag nanoparticle (NP)-decorated 1T MoS2 NSs via a liquid exfoliation method with lithium intercalation and simple reduction of AgNO3 in NaBH4. Ag NPs were uniformly distributed on the MoS2 surface with the assistance of 3-mercapto propionic acid. Ag NPs with the size of a few nanometers enhanced the conductivity of the MoS2 NS and improved the electrochemical performance of the MoS2 anode. Specifically, the anode designated as Ag3@MoS2 (prepared with AgNO3 and MoS2 in a weight ratio of 1:10) exhibited the best cycling performance and delivered a reversible specific capacity of 510 mAh·g−1 (approximately 73% of the initial capacity) after 100 cycles. Moreover, the rate performance of this sample had a remarkable recovery capacity of ~100% when the current decreased from 1 to 0.1 A·g−1. The results indicate that the Ag nanoparticle-decorated 1T MoS2 can be employed as a high-rate capacity anode in lithium-ion storage applications.

Section: Resultsmentioning

confidence: 99%

Ag Nanoparticle-Decorated MoS2 Nanosheets for Enhancing Electrochemical Performance in Lithium Storage

Nguyen

2021

Nanomaterials

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“…The electrode with >2 layers of MoS 2 NSs showed the worst cyclic performance, retaining a discharge/charge capacity of only 103/102 mAh·g −1 at the 100th cycle ( Figure 7 c). Furthermore, the charge-transfer resistance of the cells was measured from the EIS analysis, as depicted in Figure 7 d. The modified Randles equivalent circuit was determined to contain a series resistance (R s ), a charge-transfer resistance (R ct ), an SEI resistance (R SEI ), and a Warburg impedance element (W) ( Figure 7 d inset) [ 4 ]. The extracted values of these resistances are shown in Table 1 .…”

Section: Resultsmentioning

confidence: 99%

“…The issues requiring attention in the development of LIBs are low anode capacity, degradation, and mechanical instability in LIB structures due to anode material expansion by the insertion and extraction of lithium ions. To improve LIB characteristics, several anode materials have been considered, such as metal alloys, metal oxides, and transition metal chalcogenides (TMCs) [ 3 , 4 , 5 ]. Recently, the use of metal oxide materials such as TiO 2 , SnO 2 , Fe 2 O 3 , and V 2 O 5 for lithium-ion storage anodes has attracted much attention owing to their chemical stability and high reversible capacity [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ].…”

Section: Introductionmentioning

confidence: 99%

Self-Assembled Few-Layered MoS2 on SnO2 Anode for Enhancing Lithium-Ion Storage

Nguyen

2020

Nanomaterials

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SnO2 nanoparticles (NPs) have been used as reversible high-capacity anode materials in lithium-ion batteries, with reversible capacities reaching 740 mAh·g−1. However, large SnO2 NPs do not perform well in charge–discharge cycling. In this work, we report the incorporation of MoS2 nanosheet (NS) layers with SnO2 NPs. SnO2 NPs of ~5 nm in diameter synthesized by a facile hydrothermal precipitation method. Meanwhile, MoS2 NSs of a few hundreds of nanometers to a few micrometers in lateral size were produced by top-down chemical exfoliation. The self-assembly of the MoS2 NS layer on the gas–liquid interface was first demonstrated to achieve up to 80% coverage of the SnO2 NP anode surface. The electrochemical properties of the pure SnO2 NPs and MoS2-covered SnO2 NP anodes were investigated. The results showed that the SnO2 electrode with a single-layer MoS2 NS film exhibited better electrochemical performance than the pure SnO2 anode in lithium storage applications.

“…By applying further constraints or considering secondary criteria, we could reduce the statistical uncertainty and increase the physical meaning of the refined parameters. Therefore, the low-frequency constraint suggested by Vo et al was applied to refine R ct [ 65 ]. In Figure 7 c and d, the trend line of the sum of impedances (Z real + Z imag ) at low frequency had a negative slope and an X-intercept of 882 Ω, which are the sum of resistances (R s + R SEI + R ct ).…”

Section: Resultsmentioning

confidence: 99%

GeTe-TiC-C Composite Anodes for Li-Ion Storage

2020

Materials

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Germanium boasts a high charge capacity, but it has detrimental effects on battery cycling life, owing to the significant volume expansion that it incurs after repeated recharging. Therefore, the fabrication of Ge composites including other elements is essential to overcome this hurdle. Herein, highly conductive Te is employed to prepare an alloy of germanium telluride (GeTe) with the addition of a highly conductive matrix comprising titanium carbide (TiC) and carbon (C) via high-energy ball milling (HEBM). The final alloy composite, GeTe-TiC-C, is used as a potential anode for lithium-ion cells. The GeTe-TiC-C composites having different combinations of TiC are characterized by electron microscopies and X-ray powder diffraction for structural and morphological analyses, which indicate that GeTe and TiC are evenly spread out in the carbon matrix. The GeTe electrode exhibits an unstable cycling life; however, the addition of higher amounts of TiC in GeTe offers much better electrochemical performance. Specifically, the GeTe-TiC (20%)-C and GeTe-TiC (30%)-C electrodes exhibited excellent reversible cyclability equivalent to 847 and 614 mAh g−1 after 400 cycles, respectively. Moreover, at 10 A g−1, stable capacity retentions of 78% for GeTe-TiC (20%)-C and 82% for GeTe-TiC (30%)-C were demonstrated. This proves that the developed GeTe-TiC-C anodes are promising for potential applications as anode candidates for high-performance lithium-ion batteries.