Two-dimensional (2D) MoS2 nanomaterials have been extensively studied due to their special structure and high theoretical capacity, but it is still a huge challenge to improve its cycle stability and ...achieve superior fast charge and discharge performance. Herein, a facile one-step hydrothermal method is proposed to synthetize an ordered and self-assembled MoS2 nanoflower (MoS2/C NF) with expanded interlayer spacing via embedding a carbon layer into the interlayer. The carbon layer in the MoS2 interlayer can speed the transfer of electrons, while the nanoflower structure promotes the ions transport and improves the structural stability during the charging/discharging process. Therefore, MoS2/C NF electrode exhibits exceptional rate performance (318.2 and 302.3 mA·h·g−1 at 5.0 and 10.0 A·g−1, respectively) and extraordinary cycle durability (98.8% retention after 300 cycles at a current density of 1.0 A·g−1). This work provides a simple and feasible method for constructing high-performance anode composites for sodium ion batteries with excellent cycle durability and fast charge/discharge ability.
As an intercalation–conversion cathode, iron fluoride cathode with ultrahigh energy density has been extensively studied. Nevertheless, the intrinsic low electric conductivity induced by the ionic ...nature of F-Fe restricts its electrochemical activity and results in poor electrochemical reversibility, thus preventing its practical application in Li-ion batteries. Hence, it is important to enhance the electric conductivity of FeF
3
·0.33H
2
O for improving its electrochemical properties. Herein, first-principles calculations elucidate that the electric conductivity of FeF
3
·0.33H
2
O can be enhanced owing to the band gap reduction by Al-doping. Then, Fe
1-
x
Al
x
F
3
·0.33H
2
O/C (
x
= 0 and 0.08) nanocomposites are prepared by a simple solvothermal approach and ball-milling route. Electrochemical tests demonstrate that Al-doping can greatly enhance the electrochemical properties of FeF
3
·0.33H
2
O/C. Based on the synergistic effect of Al-doping and ball milling, the Fe
0.92
Al
0.08
F
3
·0.33H
2
O/C sample delivers a high reversible capacity of 164.0 mAh g
-1
at 40 mA g
-1
in the region of 2.0-4.5 V after 100 cycles and good rate capability.
Graphical abstract
With the proliferation of energy storage and power applications, electric vehicles particularly, solid-state batteries are considered as one of the most promising strategies to address the ...ever-increasing safety concern and high energy demand of power devices. Here, we demonstrate the Al
4
B
2
O
9
nanorods-modified poly(ethylene oxide) (PEO)-based solid polymer electrolyte (ASPE) with high ionic conductivity, wide electrochemical window, decent mechanical property and nonflammable performance. Specifically, because of the longer-range ordered Li
+
transfer channels conducted by the interaction between Al
4
B
2
O
9
nanorods and PEO, the optimal ASPE (ASPE-1) shows excellent ionic conductivity of 4.35×10
−1
and 3.1×10
−1
S cm
−1
at 30 and 60°C, respectively. It also has good electrochemical stability at 60°C with a decomposition voltage of 5.1 V. Besides, the assembled LiFePO
4
//Li cells show good cycling performance, delivering 155 mA h g
−1
after 300 cycles at 1 C under 60°C, and present excellent low temperature adaptability, retaining over 125 mA h g
−1
after 90 cycles at 0.2 C under 30°C. These results verify that the addition of Al
4
B
2
O
9
nanorods can effectively promote the integrated performance of solid polymer electrolyte.
The dissolution of LiNO3 in carbonate electrolytes is achieved by introducing pyridine as a new carrier solvent owing to its higher Gutmann donor number than NO3−. The Li metal anode in ...LiNO3-containing carbonate electrolyte demonstrates a much enhanced reversibility due to the preferential reduction of LiNO3 and the formation of an inorganic-rich SEI.
Phthalocyanine-based covalent organic frameworks (NA-NiPc, PPDA-NiPc and DAB-NiPc) with different pore sizes are synthesized by a catalyst-free coupling reaction, which inhibits dissolution in the ...electrolyte and provides large specific surface area and open mesoporous channels for Li+. As the pore size of the frame increases, the surface area of the material increases accordingly, resulting in improved electrochemical behaviors. The NA-NiPc, PPDA-NiPc and DAB-NiPc electrodes display high capacity, long cycling stability, and excellent rate capability both in LIBs and NIBs.
Display omitted
•Pc-based frameworks with different pore sizes of 1.55, 2.11 and 2.74 nm are synthesized.•No solubility in electrolyte and large specific surface areas are observed.•The surface area increases with the pore size, resulting in improved electrochemical behaviors.•Excellent capacity, cycle stability, and rate capability both in LIBs and NIBs are observed.
In this work, three kinds of phthalocyanine-based covalent organic frameworks, NA-NiPc (4-nitronickel phthalocyanine + 4-aminonickel phthalocyanine), PPDA-NiPc (4-nitronickel phthalocyanine + p-phenylenediamine) and DAB-NiPc (4-nitronickel phthalocyanine + 4,4′-diaminobiphenyl), with different pore sizes are synthesized by a catalyst-free coupling reaction. The X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and Transmission electron microscopy (TEM) test results indicate that the pore sizes of the NA-NiPc, PPDA-NiPc and DAB-NiPc frameworks are approximately 1.55 nm, 2.11 nm and 2.74 nm, respectively, which is consistent with the simulated results after optimizing the geometric conformation by HyperChem software; additionally, the specific surface areas are 382, 471 and 575 m2 g−1 respectively. As the pore size of the frame increases, the surface area of the material increases accordingly, resulting in different electrochemical behaviors. The initial capacities of the NA-NiPc, PPDA-NiPc and DAB-NiPc electrodes in lithium-ion batteries are 422, 469 and 566 mAh/g, respectively, and after 700 cycles, the capacities remain at 557, 670 and 941 mAh/g, demonstrating capacity retention rates of 131.8%, 142.9% and 166%, respectively, at a current density of 100 mA/g. Even at a high current density of 2 A/g, high specific capacities of 385, 512 and 767 mAh/g can still be observed. Moreover, the use of the NA-NiPc, PPDA-NiPc and DAB-NiPc electrodes in sodium-ion batteries also display excellent behaviors, such as high capacities, stable cycling performances and excellent rate capabilities. With increasing framework porosity, the performances of both lithium-ion and sodium-ion batteries gradually improve, fully indicating that the size of the framework is the key factor in determining the performance of a battery.
The dissolution of LiNO 3 in carbonate electrolytes is achieved by introducing pyridine as a new carrier solvent owing to its higher Gutmann donor number than NO 3 − . The Li metal anode in LiNO 3 ...-containing carbonate electrolyte demonstrates a much enhanced reversibility due to the preferential reduction of LiNO 3 and the formation of an inorganic-rich SEI.
Heterostructures have gained intensive attentions in various energy storage fields due to their diverse physicochemical properties and functions, originating from the synergistic effects and ...interfacial interaction between the different components. However, it is still a great challenge to employ simple methods to design an advanced heterostructure for superior sodium storage performances. Herein, a facile in situ localized phase transformation strategy has been developed to transfer MoO3 nanoparticles anchored on rGO nanosheets into MoO2@MoS2 heterostructures (MoO2@MoS2/rGO). Benefiting from faster ion transport at the heterogeneous interface, higher conductivity as well as more active sites for Na storage than that of single component, MoO2@MoS2/rGO electrode exhibits distinguished reversible capacity (604.1 mAh g−1 at 0.1 A g−1) and remarkable rate performance (420.8 mAh g−1 at 5.0 A g−1) when evaluated as an anode for SIBs. This work provides a simple and feasible method for constructing stable heterostructures for high-performance energy storage materials.
The electrochemical properties and thermal stability of the LiNi0.6Co0.2Mn0.2O2 (NCM622) material have been significantly improved by Nb2O5 nanocoating. The electrochemical properties were researched ...systematically by various electrochemical tests, and the molar ratio of Nb2O5 to NCM622 was evaluated as 0.5 mol%. Results showed that Nb2O5 nanocoated sample exhibited good cyclic performance, whose capacity retention was 92.36%, whereas that of the bare NCM was only 87.59% after 200 cycles under 1C at 25 °C. In addition, the Nb2O5 surface-coated sample exhibited a good discharge capacity of 164.05 mAh g−1 after 200 cycles under 1C at 60 °C. The result owing to the nano coating of Nb2O5, which greatly increased the thermal stability, thereby maintaining remarkable specific capacity even in high-temperature environments. The modified sample could maintain a relatively complete structure after cycling, whereas the bare sample had already collapsed. Based on the transmission electron microscopic images, the thickness of the coating layer was about 15 nm. The nanocoating of Nb2O5 was prepared by solid-phase reaction. This method is simple and convenient, which is conducive to industrial production and commercialisation promotion. The Nb2O5 surface coating can enhance the electrochemical properties of the cathode materials, as well as strengthen the thermal and structural stability, which can extend the battery life.
A novel modified reagent of butyl acrylate (BA) is introduced to improve the low-temperature performance of lithium-ion batteries (LIBs). Although the BA reagent has a slightly higher viscosity, it ...has a very low melting point and a very high dielectric constant, which makes the electrolyte have a high ionic conductivity, and finally the low temperature performance of lithium ion battery is obviously improved. The discharge capacities of BA0% were 116.67, 107.79, 95.65 and 74.31 mAh g−1 at −10 °C, −20 °C, −30 °C and −40 °C, respectively. After adding 16% BA to the electrolyte, the discharge capacities of BA16% were 127.89, 125.13, 113.28 and 91.50 mAh g−1 at −10 °C, −20 °C, −30 °C and −40 °C, with the increase of 9.6%, 16.1%, 18.4% and 23.1%, respectively. Moreover, ethylene carbonate (EC) is added as another modification reagent which can further improve the conductivity, increase the low-temperature capacity and achieve a better cyclic stability. As a result, the largest capacity could reach 169.12, 149.05, 138.15 and 108.94 mAh g−1 for the EC16% + EC10% battery, with the room-temperature capacity (identified as 180 mAh g−1) retention rates of 94.0%, 82.8%, 76.8% and 60.5% at −10, −20, −30 and −40 °C respectively, which are much higher than those of BA0%, BA 8%, BA12% and 16% batteries. The mixed additives of BA + EC can not only improve the low temperature discharge capacity, but also enhance the discharge voltage platform, which provides a new insight to improve the low-temperature performance of LIBs.
Display omitted
•Novel butyl acrylate (BA) with low melting point and high dielectric constant was introduced.•The BA can effectively improve the ionic conductivity and low temperature performance.•EC with high dielectric constant is used to further improve the ionic conductivity.•The capacity, discharge voltage platform, cycle and rate performance are obviously improved.•The additives of BA + EC can effectively improve the low temperature performance of LIBs.
Li4Ti5O12 (LTO) anode materials have attracted attention owing to its structural stability and negligible volume change. However, its application is still restricted due to the low conductivity and ...Li+ diffusion coefficient. To address these disadvantages, herein, Y3+ doped Li4Ti5-xYxO12 (LYTO) with Y2Ti2O7 surface modification anode materials have been synthesized by an easy solid-state reaction with ball milling activating method using Y(NO3)3 as the dopant. The structural analysis shows that Y3+ doping does not change the crystal structure of LTO and exhibits a uniform particle size distribution. When applied to the anodes of lithium ion batteries, Li4Ti4.8Y0.2O12 possess outstanding long-cycle stability and excellent rate performance. The discharge specific capacity achieves 173 mAh g−1 after 300 cycles at a current density of 1 A g−1 and the voltage range of 1–3 V and 92 mAh g−1 after 1000 cycles at the current density of 7 A g−1 (40C), respectively. In addition, full cells are assembled using Li4Ti4.8Y0.2O12 as anodes and LiCoO2 as cathodes. The specific capacity of coin full cell remains 150 mAh g−1 after 100 cycles at 0.2C, while the pouch full cell exhibits 149 mAh g−1 under the same conditions. These results clearly confirm that LYTO can be considered as a promising electrode material for high performance lithium-ion batteries.
Display omitted
•Y3+ doped Li4Ti5-xYxO12 with Y2Ti2O7 surface modification have been synthesized.•Li4Ti5-xYxO12 anodes in half-cells possess superior rate capability and ultra-long life.•Y20 anodes exhibit a prominent full cell performances.
PDF
