Highlights
N-Ti
3
C
2
@CNT microspheres are successfully synthesized by the simple spray drying and one-step pyrolysis.
Within the microsphere, MXene nanosheets intimately interact with CNTs ...constructing porous and highly conductive network, which can provide strong immobilization for polysulfides.
N-Ti
3
C
2
@CNT microsphere/S cathode shows highly cycling stability in lithium-sulfur battery.
Herein, N-Ti
3
C
2
@CNT microspheres are successfully synthesized by the simple spray drying method. In the preparation process, HCl-treated melamine (HTM) is selected as the sources of carbon and nitrogen. It not only realizes in situ growth of CNTs on the surface of MXene nanosheets with the catalysis of Ni, but also introduces efficient N-doping in both MXene and CNTs. Within the microsphere, MXene nanosheets interconnect with CNTs to form porous and conductive network. In addition, N-doped MXene and CNTs can provide strong chemical immobilization for polysulfides and effectively entrap them within the porous microspheres. Above-mentioned merits enable N-Ti
3
C
2
@CNT microspheres to be ideal sulfur host. When used in lithium–sulfur (Li–S) battery, the N-Ti
3
C
2
@CNT microspheres/S cathode delivers initial specific capacity of 927 mAh g
−1
at 1 C and retains high capacity of 775 mAh g
−1
after 1000 cycles with extremely low fading rate (FR) of 0.016% per cycle. Furthermore, the cathode still shows high cycling stability at high C-rate of 4 C (capacity of 647 mAh g
−1
after 650 cycles, FR 0.027%) and high sulfur loading of 3 and 6 mg cm
−2
for Li–S batteries.
Highlights
A facile NH
4
+
method was proposed to prepare Sn nanocomplex pillared few-layered Ti
3
C
2
T
x
MXene nanosheets.
The MXene nanosheets showed excellent lithium-ion storage performances ...among MXene-based materials, which can maintain 1016 mAh g
−1
after 1200 cycles at 2000 mA g
−1
and deliver a stable capacity of 680 mAh g
−1
at 5 A g
−1
.
MXenes have attracted great interest in various fields, and pillared MXenes open a new path with larger interlayer spacing. However, the further study of pillared MXenes is blocked at multilayered state due to serious restacking phenomenon of few-layered MXene nanosheets. In this work, for the first time, we designed a facile NH
4+
method to fundamentally solve the restacking issues of MXene nanosheets and succeeded in achieving pillared few-layered MXene. Sn nanocomplex pillared few-layered Ti
3
C
2
T
x
(STCT) composites were synthesized by introducing atomic Sn nanocomplex into interlayer of pillared few-layered Ti
3
C
2
T
x
MXenes via pillaring technique. The MXene matrix can inhibit Sn nanocomplex particles agglomeration and serve as conductive network. Meanwhile, the Sn nanocomplex particles can further open the interlayer spacing of Ti
3
C
2
T
x
during lithiation/delithiation processes and therefore generate extra capacity. Benefiting from the “pillar effect,” the STCT composites can maintain 1016 mAh g
−1
after 1200 cycles at 2000 mA g
−1
and deliver a stable capacity of 680 mAh g
−1
at 5 A g
−1
, showing one of the best performances among MXene-based composites. This work will provide a new way for the development of pillared MXenes and their energy storage due to significant breakthrough from multilayered state to few-layered one.
Due to easy re-stacking, low yield of few-layered MXenes (f-MXenes), the applications of MXenes are mainly restricted in multi-layered MXenes (m-MXenes) state. Although f-MXenes can be prepared from ...m-MXenes, after exfoliation process, a mass of sediments which are still essentially compact MXenes are usually directly discarded, leading to low utilization of raw m-MXenes. Herein, a classified preparation strategy is adopted to exploit the raw m-MXenes and traditional MXenes sediments, taking multi-layered Ti
3
C
2
T
x
MXene as an example. Via rational delamination and subsequent treatment to Ti
3
C
2
T
x
sediments, we succeed in achieving classified and large-scale preparation of various Ti
3
C
2
T
x
MXene derivatives, including few-layered Ti
3
C
2
T
x
(f-Ti
3
C
2
T
x
) powders, f-Ti
3
C
2
T
x
films, and Ti
3
C
2
T
x
MXene-derived nanowires with heterostructure of potassium titanate and Ti
3
C
2
T
x
. We demonstrate the necessity of “step-by-step delamination” towards traditional Ti
3
C
2
T
x
sediments to improve the yield of f-Ti
3
C
2
T
x
from 15% to 72%; the feasibility of “solution-phase flocculation (SPF)” to fundamentally solve the re-stacking phenomenon, and oxidation degradation issues of f-Ti
3
C
2
T
x
during storage; as well as the convenience of SPF to deal with time-consuming issues of fabricating Ti
3
C
2
T
x
films. What’s more, alkali-heat treatment of final Ti
3
C
2
T
x
sediments turns waste into treasure of Ti
3
C
2
T
x
-derived nanowires, leading to 100% utilization of raw Ti
3
C
2
T
x
. The content of one-dimensional (1D) nanowires in the hybrids can be adjusted by controlling alkalization time. The 3D architecture heterostructure composed of 1D nanowires and 2D nanosheets exhibits gorgeous application potential. This work can expand preparation and application of various MXenes derivatives, promoting process of various MXenes.
Highlights
Freestanding multicapsular carbon fibers (MCFs) cloth was synthesized by electrospinning and applied as interfacial layer to regulate the plating/stripping behavior of Zn anodes.
MCFs ...layer is supposed to uniformize the electric field and Zn
2+
flux, and the moderate zincophilicity enables the bottom-up deposition of Zn on Zn@MCFs anode, thereby leading to high-quality and rapid Zn deposition kinetics.
Superior electrochemical performance of Zn@MCFs is achieved in symmetrical, asymmetrical and Zn||MnO
2
batteries, including long cycling life, high coulombic efficiency and excellent rate performance.
Aqueous rechargeable zinc ion batteries are regarded as a competitive alternative to lithium-ion batteries because of their distinct advantages of high security, high energy density, low cost, and environmental friendliness. However, deep-seated problems including Zn dendrite and adverse side reactions severely impede the practical application. In this work, we proposed a freestanding Zn-electrolyte interfacial layer composed of multicapsular carbon fibers (MCFs) to regulate the plating/stripping behavior of Zn anodes. The versatile MCFs protective layer can uniformize the electric field and Zn
2+
flux, meanwhile, reduce the deposition overpotentials, leading to high-quality and rapid Zn deposition kinetics. Furthermore, the bottom-up and uniform deposition of Zn on the Zn-MCFs interface endows long-term and high-capacity plating. Accordingly, the Zn@MCFs symmetric batteries can keep working up to 1500 h with 5 mAh cm
−2
. The feasibility of the MCFs interfacial layer is also convinced in Zn@MCFs||MnO
2
batteries. Remarkably, the Zn@MCFs||α-MnO
2
batteries deliver a high specific capacity of 236.1 mAh g
−1
at 1 A g
−1
with excellent stability, and maintain an exhilarating energy density of 154.3 Wh kg
−1
at 33% depth of discharge in pouch batteries.
Rechargeable multivalent ion (Al 3+ , Mg 2+ and Zn 2+ ) batteries provide a viable alternative to lithium ion batteries because of the supply risk of lithium resources and safety concern. In this ...study, rechargeable metal–iodine batteries, particularly aluminum/iodine batteries, were fabricated with novel active carbon cloth/polyvinylpyrrolidone (ACC/PVPI) composite cathodes prepared via a facile solution-adsorption method combined with freeze-drying. The use of active carbon cloth (ACC) endows the composites superior electronic conductivity, and significantly decreases the weight of the electrode due to its function as a current collector. Hydrogen bonding interaction between PVP and iodine in PVPI guarantees the depression of the shuttle effect of polyiodide, thus lengthening the cycle life. The density functional theory (DFT) analysis shows that such shuttle depression occurs due to the hydrogen-bonded iodine species, and the relatively large formation energy hints at higher conversion reaction efficiency of Al ion batteries. These characteristics make the composites an ideal electrode in various metal ion batteries. To be specific, the Al/I 2 battery with a distinct working potential window achieves a high capacity of 180.1 mA h g −1 at 0.2C and can remain stable after 500 cycles with a stable capacity of 127 mA h g −1 at 0.6C. Moreover, at higher current density of 1C, the battery delivers a capacity of 102.7 mA h g −1 for up to 1050 cycles. These above-mentioned characteristics of metal–iodine (Li, Mg and Al/I 2 ) batteries, related electrochemical performance measurements and theoretical modeling analysis show that the rechargeable iodine-based batteries provide a promising direction in designing high-performance energy storage/transfer systems.
Silicon is investigated as one of the most prospective anode materials for next generation lithium ion batteries due to its superior theoretical capacity (3580 mAh g
), but its commercial application ...is hindered by its inferior dynamic property and poor cyclic performance. Herein, we presented a facile method for preparing silicon/tin@graphite-amorphous carbon (Si/Sn@G-C) composite through hydrolyzing of SnCl
on etched Fe-Si alloys, followed by ball milling mixture and carbon pyrolysis reduction processes. Structural characterization indicates that the nano-Sn decorated porous Si particles are coated by graphite and amorphous carbon. The addition of nano-Sn and carbonaceous materials can effectively improve the dynamic performance and the structure stability of the composite. As a result, it exhibits an initial columbic efficiency of 79% and a stable specific capacity of 825.5 mAh g
after 300 cycles at a current density of 1 A g
. Besides, the Si/Sn@G-C composite exerts enhanced rate performance with 445 mAh g
retention at 5 A g
. This work provides an approach to improve the electrochemical performance of Si anode materials through reasonable compositing with elements from the same family.
All-solid-state lithium batteries (ASSLBs) employ high-capacity lithium (Li) metal as the anode and exhibit a higher energy density than that of conventional Li-ion batteries. However, the problems ...arose from the Li dendrites induce severely parasitic reaction between Li and electrolytes, leading to low coulombic efficiency (CE) and poor cyclic stability. Herein, a poly(vinylidene-co-hexafluoropropylene)/lithium nitrate (PVDF-HFP/LiNO3, marked as PFH/LN) artificial layer is employed to modified Li and achieve high CE ASSLBs with polyethylene oxide-Li6.4La3Zr1.4Ta0.6O12 (PEO-LLZTO) electrolyte. LN serves as a functionalized additive to facilitate the formation of a robust solid electrolyte interface (SEI), efficiently suppressing the formation of Li dendrites. Additionally, LN as a “binder” effectively links PFH with Li, providing good contact. PFH possesses high mechanical strength and moderate flexibility, which can not only physically inhibit the growth of Li dendrites, but also maintain the structural integrity of artificial layer over long-term cycles. Finally, Li/Li cells with such artificial layer demonstrate ultralong cycle life of 1800 and 1000 h under 0.2 and 0.4 mA cm−1, respectively. Furtherly, high CE can be achieved when applied in both LiFePO4 full cells and Li-Cu half cells. This work offers a facile and efficient strategy to greatly promote CE in PEO-based ASSLBs.
Display omitted
•A robust artificial layer is constructed to modify Li metal through a simple solution casting strategy.•The artificial layer can induce the formation of highly stable SEI over cycles.•The artificial layer can ensure the uniform deposition of Li metal and the efficient suppression of Li dendrites.•High coulombic efficiency can be achieved in both LiFePO4 full cell and Li-Cu half cell.
Display omitted
•Few-layered Ti3C2 MXene is prepared by solution-phase flocculation strategy.•NiCo2Se4 nanoparticles are anchored on few-layered MXene forming 3D structures.•The hybrids exhibit ...superior sodium storage performance.•Dual sodium storage mechanisms have been verified by ex-situ XRD technique.
In order to facilitate the sluggish Na+ insertion/extraction kinetics and improve the poor structural durability of sodium-ion batteries (SIBs) anodes, we for the first time rationally fabricate few-layered Ti3C2/NiCo2Se4 3D architectures (f-Ti3C2/NiCo2Se4) as anodes for SIBs via a facile solvothermal approach with assistance of solution-phase flocculation strategy to avoid restacking issue of few-layered Ti3C2 MXene nanosheets (f-Ti3C2 MXene). The 0D bimetallic selenide NiCo2Se4 nanoparticles as a Na+ reservoir with higher redox activity are uniformly decorated on f-Ti3C2 MXene, effectively preventing the self-restacking of f-Ti3C2 MXene. A fast electron/Na+ transport ability and high surface-to-volume ratio provided by the unique f-Ti3C2 MXene substrate endow the composites with rapid charge transfer kinetics and intimate contact between electrolyte and electrode. Meanwhile, f-Ti3C2 MXenes are able to act as a flexible skeleton to facilitate strain relief and restrain pulverization of NiCo2Se4 nanoparticles during cycling. As a result, the 0D/2D NiCo2Se4/f-Ti3C2 hybrids exhibit superior cyclic stability and outstanding rate performance when applied in SIBs. Furthermore, dual sodium storage mechanisms of conversion reaction for NiCo2Se4 and intercalation/de-intercalation for f-Ti3C2 MXene among the hybrids have been verified by ex-situ XRD technique. The presented strategy can also be used to tackle the intrinsic problems of various bimetallic selenides by integrating them with few-layered MXene to fabricate hybrids for SIBs anodes.
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