A peculiar nanostructure consisting of nitrogen-doped, carbon-encapsulated (N–C) SnO2@Sn nanoparticles grafted on three-dimensional (3D) graphene-like networks (designated as N–C@SnO2@Sn/3D-GNs) has ...been fabricated via a low-cost and scalable method, namely an in situ hydrolysis of Sn salts and immobilization of SnO2 nanoparticles on the surface of 3D-GNs, followed by an in situ polymerization of dopamine on the surface of the SnO2/3D-GNs, and finally a carbonization. In the composites, three-layer core–shell N–C@SnO2@Sn nanoparticles were uniformly grafted onto the surfaces of 3D-GNs, which promotes highly efficient insertion/extraction of Li+. In addition, the outermost N–C layer with graphene-like structure of the N–C@SnO2@Sn nanoparticles can effectively buffer the large volume changes, enhance electronic conductivity, and prevent SnO2/Sn aggregation and pulverization during discharge/charge. The middle SnO2 layer can be changed into active Sn and nano-Li2O during discharge, as described by SnO2 + Li+ → Sn + Li2O, whereas the thus-formed nano-Li2O can provide a facile environment for the alloying process and facilitate good cycling behavior, so as to further improve the cycling performance of the composite. The inner Sn layer with large theoretical capacity can guarantee high lithium storage in the composite. The 3D-GNs, with high electrical conductivity (1.50 × 103 S m–1), large surface area (1143 m2 g–1), and high mechanical flexibility, tightly pin the core–shell structure of the N–C@SnO2@Sn nanoparticles and thus lead to remarkably enhanced electrical conductivity and structural integrity of the overall electrode. Consequently, this novel hybrid anode exhibits highly stable capacity of up to 901 mAh g–1, with ∼89.3% capacity retention after 200 cycles at 0.1 A g–1 and superior high rate performance, as well as a long lifetime of 500 cycles with 84.0% retention at 1.0 A g–1. Importantly, this unique hybrid design is expected to be extended to other alloy-type anode materials such as silicon, germanium, etc.
Full text
Available for:
IJS, KILJ, NUK, PNG, UL, UM
A three-dimensional Li4Ti5O12/carbon nanotubes/graphene composite (LTO-CNT-G) was prepared by ball-milling method, followed by microwave heating. The as-prepared LTO-CNT-G composite as anode material ...in lithium-ion battery exhibited superior rate capability and cycle performance under relative high current density compared with that of Li4Ti5O12/CNTs (LTO-CNT) and Li4Ti5O12/graphene (LTO-G) composites. Graphene nanosheets and CNTs were used to construct 3D conducting networks, leading to faster electron transfer and lower resistance during the lithium ion reversible reaction, which significantly enhanced the electrochemical activity of LTO-CNT-G composite. The synergistic effect of graphene and CNTs can greatly improve the rate capability and cycling stability of Li4Ti5O12-based anodes. The LTO-CNT-G composite exhibited a high initial discharge capacity of 172 mAh g−1 at 0.2 C and 132 mAh g−1 at 20 C, as well as an excellent cycling stability. The electrochemical impedance spectroscopy demonstrated that the LTO-CNT-G composite has the smallest charge-transfer resistance compared with the LTO-CNT and LTO-G composites, indicating that the fast electron transfer from the electrolyte to the LTO-CNT-G active materials during the lithium ion intercalation/deintercalation owing to the three-dimensional networks of graphene and CNTs.
•A three-dimensional Li4Ti5O12/CNTs/graphene (LTO-CNT-G) composite was prepared by simple ball-milling method.•The CNTs/graphene conducting networks can greatly improve the conductivity of LTO-CNT-G anode.•The three-dimensional CNTs/graphene conducting networks can greatly improve the reversible capacity and rate capability in lithium ion batteries.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Lithium-sulfur batteries (LSBs) have been regarded as a prospective candidate for next-generation late-model energy storage device due to their merits in gravimetric/ volumetric capacity. However, ...the practical use of LSBs is still severely limited by the shuttle behavior and extremely slow bidirectional sulfur redox kinetics. Herein, a dual-functional conductive 1T-MoSe2/MXene bidirectional catalyst as a high-efficiency sulfur host was constructed by few-layer 1T-MoSe2 in-situ growth on MXene nano-flakes through one-step solvothermal reaction. Experimental and DFT theoretical analysis reveal that 1T-MoSe2/MXene possess a high electronic conductivity, strong adsorption ability, and abundant active sites, which can provide the strong capture and catalytic conversion ability for LiPSs and uniform deposition and dissolution of Li2S, thus effectively inhibiting the LiPSs shuttle behavior in LSBs. Benefiting from the enhanced bidirectional sulfur redox kinetics and adsorption capacity, the S/1T-MoSe2/MXene cathode delivers a stable long cycling stability with a capacity retention of64.2% (capacity fading per cycle of 0.07%) after 500 cycles at 0.2 C. Furthermore, a high areal capacity of 6.9 mAh cm−2 and good capacity retention of ∼73.1% were obtained after 200 cycles at 0.1 C. This work provides a novel way for the development of dual-functional conductive catalyst to accelerate the catalytic conversion of LiPSs.
Display omitted
•A conductive 1T-MoSe2/MXene bidirectional catalyst as a high-efficiency sulfur host was constructed by few-layer 1T-MoSe2 in-situ growth on MXene.•1T-MoSe2/MXene possess a high electronic conductivity, strong adsorption ability and abundant active sites.•1T-MoSe2/MXene catalyst can accelerate bidirectional sulfur redox kinetics, regulate Li2S nucleation and decomposition, and depress polysulfide shuttling.•S/1T-MoSe2/MXene cathode gives a stable long-term lifespan with 500 cycles and a high areal capacity of 6.9 mAh cm−2.•Experimental and calculation results verified its excellent adsorption and catalytic conversion ability.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Although metal-cation doping into transition-metal dichalcogenides (TMDCs) has been investigated for promoting stepwise sulfur redox in lithiumsulfur batteries (LSBs), a rational design principle and ...a systematic theoretical study on how to select a suitable metal-cation dopant for doping into TMDCs to tune their catalytic activity are lacking in LSBs. Herein, we demonstrate a general electron affinity/ionic radius (
E
A
/
r
) rule as a new selection criterion of metal-cation dopants to guide the design of efficient metal-cation-doped LiS catalysts. And a series of metal-cation dopants with different
E
A
/
r
values into WSe
2
as a model to engineer their electronic structure and catalytic activity for manipulating sulfur redox kinetics are systematically investigated. Theoretical and experimental results reveal that a low
E
A
/
r
value of metal-cation dopant easily induces more Se vacancies and lattice defects, increases active sites and more electron accumulation on surface Se sites for stronger binding with lithium polysulfides (LiPSs), but it also weakens the competing LiS bonds in LiPSs/Li
2
S captured on the host surface, thereby increasing LiPSs adsorption yet decreasing the Li
2
S nucleation and decomposition energy barrier. As expected, the V-doped WSe
2
/MXene catalyst with a minimum
E
A
/
r
value as a high-efficiency sulfur host exhibits the highest reversible capacity (1402.5 mAh g
1
), a long-term cycling stability with 800 cycles (70% retention), and a large areal capacity (6.4 mAh cm
2
). This work provides a general design rule as the selection criterion of metal-cation dopants to tune the catalytic activity for designing advanced LiS catalysts.
A general affinity/ionic radius (
E
A
/
r
) rule as the selection criteria of cation dopants for designing efficient cation doped LiS catalysts is proposed, and a low
E
A
/
r
value of doped cations greatly promotes sulfur redox in LiS batteries.
Thick electrode engineering greatly enhances the areal loading of electroactive materials and gravimetric energy density of batteries, but it brings sluggish electron/ion diffusion kinetics and ...fluffy structure (high porosity) owing to its prolonged electronic/ionic diffusion length. Herein, we develop a general soft chemical strategy to fabricate a series of ultrathick yet dense electrodes with high conductivity, which achieves high utilization of electroactive materials, ultrahigh areal and volumetric capacities. Specifically, the ultrathick dense graphene-encapsulated Na3V2(PO4)3 electrode (loading: 120 mg cm−2, thickness: 492 μm) and graphene-encapsulated LiFePO4 (HD-LFP@G) electrode (loading: 152 mg cm−2, thickness: 623 μm) achieve the utilization ratios of 73 and 90%, and the ultrahigh areal capacities of 9.3 and 21 mAh cm−2, respectively. Importantly, the ultrathick and dense HD-LFP@G//graphene-encapsulated graphite (HD-graphite@G) full batteries also displayed a high areal capacity of 9.4 mAh cm−2. Detailed mechanism analysis revealed that such superior electrochemical performance stems from its 3D high-conductivity and network-like graphene-encapsulated structure, which maintains good electronic/ionic diffusion kinetics and structural stability, while the dense structure endows high volumetric performance in the ultrathick dense electrodes. This work provides an universal strategy to design ultrathick, dense electrodes towards compact energy storage with high volumetric and gravimetric energy density in practical applications.
Display omitted
•Ultrathick dense electrodes were obtained by a general soft chemical strategy.•Ultrathick dense graphene-encapsulated LiFePO4 (152 mg cm−2) gave 90% utilization.•The ultrathick electrode also gave ultrahigh areal and volumetric capacities.•An ultrathick, dense full battery gave a high areal capacity of 9.4 mAh cm−2.•Superior performance stems from its 3D conductive, dense encapsulated structure.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Uncontrollable dendrite growth and a lack of safety and reliability in lithium-metal batteries (LMBs) severely restrict their commercial progress; therefore, designing highly safe and stable LMBs ...still face huge challenges. Herein, we in situ constructed highly nitrogen-rich triazine-based covalent organic frameworks (COFs) (N content: 47.04 at%) with a high Young's modulus (3.51 GPa) on a Li-metal surface with multiple lithiophilic sites and artificial SEI layers to reduce side reactions, induce uniform Li + flux and Li plating/stripping, and suppress dendrite growth. Theoretical and experimental analysis confirmed that the strongly lithiophilic and highly nitrogen-rich structure of COFs has multiple adsorption sites and high Li adsorption energy, which spontaneously forms a rigid organic/inorganic hybrid protection layer with rich Li–N and highly ordered pore structures, thereby inducing uniform Li + flux and Li plating/stripping, decreasing Li + migration energy barrier, enhancing Li + mobility, and suppressing Li-dendrite growth. As expected, COF@Li symmetric cells achieved an ultra-long cycling stability of over 8000 h at 5 mA cm −2 (5 mA h cm −2 ) and 1600 h at 20 mA cm −2 (20 mA h cm −2 ). Importantly, the LiFePO 4 ||COF@Li full cell exhibited an excellent cycling stability of over 1000 cycles at 5 C. This work provides an effective in situ interface engineering strategy to fabricate highly nitrogen-rich COFs as rigid, multiple-site lithiophilic protection layers on the Li metal surface for ultra-stable, dendrite-free LMBs.
The tremendous volume change and severe pulverization of micro‐sized Sb anode generate no stable capacity in potassium‐ion batteries (PIBs). The honeycomb‐like porous structure provides free spaces ...to accommodate its volume expansion and offers efficient ion transport, yet complex synthesis and low yield limits its large‐scale application. Here, a green, scalable template‐free method for designing a 3D honeycomb‐like interconnected porous micro‐sized Sb (porous‐Sb) is proposed. Its honeycomb‐like porous formation mechanism is also verified. Under hydrothermal conditions, Sb reacts with water and dissolved oxygen in water, undergoing non‐homogeneous and continuous corrosion at grain boundaries, and producing soluble H2Sb2O6 (H2O), which regulates the porous structure of Sb by controlling reaction time. Benefiting from its porous structure and micron size, porous‐Sb anode displays large gravimetric and volumetric capacities with 655.5 mAh g−1 and 2,001.9 mAh cm−3 at 0.05 A g−1 and superior rate performance of 441.9 mAh g−1 at 2.0 A g−1 in PIBs. Furthermore, ex situ characterization and kinetic analysis uncover the small volume expansion and fast K+ reaction kinetics of porous Sb during potassiation/depotassiation, originating from its large electrolyte contact area and internal expansion mechanism. It verifies a green, scalable template‐free strategy to construct honeycomb‐like porous metals for energy storage and conversion.
The authors develop a green and scalable template‐free strategy to fabricate a honeycomb‐like interconnected porous micro‐sized layered Sb, and the porous‐Sb anode presents a superior gravimetric and volumetric potassium storage performance and a high utilization. Its formation mechanism of honeycomb‐like porous structure and superior potassium storage mechanism are also uncovered.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Various P-Ge compounds including GeP5 and GeP3 can be easily synthesized by a direct ball milling method while GeP can not. Herein, we successfully synthesize binary-phase Ge2P3 composite which ...derived from layered GeP and black P. When applied as anodes for Li-ion batteries, the as-synthesized binary-phase composite delivers a large reversible capacity of 1605 mA h g−1 with a high initial Coulombic efficiency of 89%, retains 1380 mA h g−1 after 100 cycles and even achieves 920 mA h g−1 at a current density of at 5 A g−1. Also, for sodium-storage it shows a reversible capacity of 970 mA h g−1 with an initial Coulombic efficiency of 88% and retains 890 mA h g−1 after 100 cycles. The performance can be attributed to the following merits: the binary Li/Na-storage components host more Li/Na ions, the layered structure favors Li/Na-ion transportation and the abundant heterointerfaces increase the amount of active sites.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Uncontrollable dendrite growth and a lack of safety and reliability in lithium-metal batteries (LMBs) severely restrict their commercial progress; therefore, designing highly safe and stable LMBs ...still face huge challenges. Herein, we
in situ
constructed highly nitrogen-rich triazine-based covalent organic frameworks (COFs) (N content: 47.04 at%) with a high Young's modulus (3.51 GPa) on a Li-metal surface with multiple lithiophilic sites and artificial SEI layers to reduce side reactions, induce uniform Li
+
flux and Li plating/stripping, and suppress dendrite growth. Theoretical and experimental analysis confirmed that the strongly lithiophilic and highly nitrogen-rich structure of COFs has multiple adsorption sites and high Li adsorption energy, which spontaneously forms a rigid organic/inorganic hybrid protection layer with rich Li-N and highly ordered pore structures, thereby inducing uniform Li
+
flux and Li plating/stripping, decreasing Li
+
migration energy barrier, enhancing Li
+
mobility, and suppressing Li-dendrite growth. As expected, COF@Li symmetric cells achieved an ultra-long cycling stability of over 8000 h at 5 mA cm
−2
(5 mA h cm
−2
) and 1600 h at 20 mA cm
−2
(20 mA h cm
−2
). Importantly, the LiFePO
4
||COF@Li full cell exhibited an excellent cycling stability of over 1000 cycles at 5 C. This work provides an effective
in situ
interface engineering strategy to fabricate highly nitrogen-rich COFs as rigid, multiple-site lithiophilic protection layers on the Li metal surface for ultra-stable, dendrite-free LMBs.
Highly N-rich triazine-based COFs as a multiple lithiophilic SEI layer is designed
via in situ
interface engineering, which induces uniform Li
+
flux and plating/stripping, decreases the Li
+
migration barrier, and suppresses Li-dendrite growth.
2D alloy‐based anodes show promise in potassium‐ion batteries (PIBs). Nevertheless, their low tap density and huge volume expansion cause insufficient volumetric capacity and cycling stability. ...Herein, a 3D highly dense encapsulated architecture of 2D‐Bi nanosheets (HD‐Bi@G) with conducive elastic networks and 3D compact encapsulation structure of 2D nano‐sheets are developed. As expected, HD‐Bi@G anode exhibits a considerable volumetric capacity of 1032.2 mAh cm−3, stable long‐life span with 75% retention after 2000 cycles, superior rate capability of 271.0 mAh g−1 at 104 C, and high areal capacity of 7.94 mAh cm−2 (loading: 24.2 mg cm−2) in PIBs. The superior volumetric and areal performance mechanisms are revealed through systematic kinetic investigations, ex situ characterization techniques, and theorical calculation. The 3D high‐conductivity elastic network with dense encapsulated 2D‐Bi architecture effectively relieves the volume expansion and pulverization of Bi nanosheets, maintains internal 2D structure with fast kinetics, and overcome sluggish ionic/electronic diffusion obstacle of ultra‐thick, dense electrodes. The uniquely encapsulated 2D‐nanosheet structure greatly reduces K+ diffusion energy barrier and accelerates K+ diffusion kinetics. These findings validate a feasible approach to fabricate 3D dense encapsulated architectures of 2D‐alloy nanosheets with conductive elastic networks, enabling the design of ultra‐thick, dense electrodes for high‐volumetric‐energy‐density energy storage.
A 3D dense encapsulated architecture of 2D Bi nanosheets is designed. It displayed superior 3D structural stability, large volumetric capacity (1032.2 mAh g−1), ultra‐high loading (24.2 mg cm−2), large areal capacity (7.94 mAh cm−2), and long lifespan of 2000 cycles (75.0% retention) in potassium‐ion batteries.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
