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The improvements of cyclability and rate capability of lithium ion batteries with spinel LiMn2O4 as cathode are imperative demands for the large-scale practical applications. Herein, ...a nickel (Ni) and magnesium (Mg) co-doping strategy was employed to synthesize LiNi0.03Mg0.05Mn1.92O4 cathode material via a facile solid-state combustion approach. The effects of the Ni-Mg co-doping on crystalline structure, micromorphology and electrochemical behaviors of the as-prepared LiNi0.03Mg0.05Mn1.92O4 are investigated by a series of physico-chemical characterizations and performance tests at high-rate and elevated-temperature. The resultant LiNi0.03Mg0.05Mn1.92O4 has the intrinsic spinel structure with no any impurities, and exhibits an elevated average valence of manganese in comparison to the pristine LiMn2O4. Owing to the Ni and Mg dual-doped merits, the LiNi0.03Mg0.05Mn1.92O4 sample demonstrates a robust spinel structure and high first discharge specific capacity of 112.3 mAh g−1, whilst undergoing a long cycling of 1000 cycles at 1 C. At a high current rate of 20 C, the capacity of 91.2 mAh g−1 with an excellent retention of 77% is obtained after 1000 cycles. Even at 10 C under 55 °C, an excellent capacity of 97.6 mAh g−1 is also delivered. These results offer a new opportunity for developing high-performance lithium ion batteries with respect to the Ni-Mg co-doping strategy.
A series of aluminum and nickel (Al–Ni) co-doped LiAl
0.15
Ni
x
Mn
1.85−
x
O
4
composites are prepared through a facile solid-state combustion method. All the as-obtained materials show a spinel ...structure and analogous spherical morphology with uniform particle distribution. Moreover, the synergistic merits of Al and Ni dual substitutions endow the spinel LiMn
2
O
4
with an elevated Mn average valence state of 3.59 and relatively alleviative Jahn–Teller distortion. Among these samples, the LiAl
0.15
Ni
0.03
Mn
1.82
O
4
(LANMO-0.03) cathode exhibits an optimal electrochemical performance with the discharge capacities of 103.3 mAh g
−1
and 102 mAh g
−1
at 1 C and 5 C in the first cycle, and the capacity retentions are 72.0% and 68.6% after 1000 cycles, respectively. Even at 1 C and high temperature of 55 °C, an excellent capacity retention remained to be 76.6% after 200 cycles. Furthermore, the LANMO-0.03 has good Li
+
diffusion capability during charge/discharge, the D
Li
+
value of the LANMO-0.03 (1.65 × 10
–11
cm
2
∙s
−1
) is higher than that of the LiAl
0.15
Mn
1.85
O
4
(LAMO) (8.12 × 10
–12
cm
2
∙s
−1
), and the charge transfer resistances of the LAMO and LANMO-0.03 samples are almost the same at 150 Ω before cycling but decrease to 130 Ω and 95 Ω after 1000 cycles at 1 C, respectively. These results demonstrate that the Al–Ni co-doped strategy can enhance the structural stability and provide stable Li
+
diffusion channel during the long cycles even at elevated temperature. Meanwhile, the facile solid-state combustion approach can also be extended to the preparation of other dual cation-doped electrode materials.
The recycle and utilization of expired drugs is a challenge for many countries at present. The employment of expired drugs as green corrosion inhibitors is expected to address both drug recycling and ...corrosion prevention issues, with significant economic and environmental value. Herein, the individually and combination corrosion inhibition performance of expired amoxicillin (AMC) and penicillin V potassium tablets (PVP) for lowcarbon steel in 20% acetic acid solution containing 600 mg L-1 chloride ion are evaluated by electrochemistry and weight loss method. Both the AMC and PVP present the mixed-type corrosion inhibitors mainly affect the cathode process when used individually. The optimum inhibition efficiency is 61.22% (AMC) and 79.21% (PVP), which all appear in 5.0 × 10-3 mol L-1. The AMC and PVP are adsorbed on the steel surface by mixed physisorption and chemisorption, which are consistent with the Langmuir adsorption isotherm. The corrosion inhibition rate drops sharply when AMC and PVP are combined use with a close mole ratio. But a small amount of PVP significantly enhance the corrosion inhibition effect of AMC, the corrosion inhibition rate from 61.22 to 79.72%. The corrosion inhibition rate of AMC and PVP combination inhibitor decreased with the increase of temperature.
Li
1.05
Cu
0.05
Mn
1.90
O
4
cathode materials were synthesized by liquid phase combustion method at different temperatures from 400 to 700 °C. All samples show good crystallinity and conform to the ...Fd3m space group of spinel LiMn
2
O
4
. The Li
1.05
Cu
0.05
Mn
1.90
O
4
sample prepared at 600 °C has a sharp diffraction peak compared to the pristine LiMn
2
O
4
, while no impurities are detected. Both the Li–Cu co-doping and calcination temperature have effects on the morphology and particle size distribution. The electrochemical properties reveal that initial discharge capacity of the Li
1.05
Cu
0.05
Mn
1.90
O
4
is 102.4 mAh g
−1
and pristine LiMn
2
O
4
electrode is 105.3 mAh g
−1
. After 1000 cycles, the capacity retention rate of the pristine LiMn
2
O
4
(63.0%) has less than 74.3% of the Li
1.05
Cu
0.05
Mn
1.90
O
4
sample. The lithium-ion diffusion coefficient indicates that the as-prepared Li
1.05
Cu
0.05
Mn
1.90
O
4
electrode (1.58 × 10
−10
cm
2
s
−1
) at 600 °C displays better Li
+
diffusion ability when compared with the pristine LiMn
2
O
4
(8.06 × 10
−11
cm
2
s
−1
). Simultaneously, the apparent activation energy further demonstrates that the Li
1.05
Cu
0.05
Mn
1.90
O
4
(22.84 kJ/mol) electrode has lower polarization when compared with the LiMn
2
O
4
(34.95 kJ/mol) electrode. These results show that synergistic effect of the Li
+
and Cu
2+
enhances the cycle reversibility and kinetics properties in cycle of the electrode.
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The treatment of solid waste carbide slag (CS) poses an urgent challenge in terms of its resolution. This study presented an efficient and cost-effective method for simultaneous ...desulfurization and denitrification at low temperatures using different modified potassium compounds (KOH, K2CO3, and KHCO3) as adsorbents. The experimental results revealed the significant impact of potassium modification on the performance of the CS, leading to a significant improvement in its denitrification activity while maintaining the same desulfurization effect. The denitrification rates of the modified CS demonstrated increases by 30 % (KOH), 25 % (K2CO3), and 40 % (KHCO3), respectively, compared to the unmodified CS at 200 ℃. The NO adsorption capacities were 2.48 (KOH), 2.24 (K2CO3), and 3.05 (KHCO3) times that of CS, respectively. Subsequent investigations suggested that the potassium modification process induced changes in the microstructure of CS, augmenting the abundance of oxygen vacancies, KOx, C = O, and Oads, thereby enhancing the intensity and quantity of basic sites. This reduced the activation energy of the CS during simultaneous desulfurization and denitrification. In addition, it was observed that certain byproducts formed during the desulfurization and denitrification processes, such as sulfate, sulfite, and nitrate, accumulated on the surface and within the inner pores of the adsorbents, ultimately resulting in a decline in catalytic activity. This study aims to embrace the “treat waste with waste” approach and is expected to provide guidance for the advancement of simultaneous desulfurization and denitrification technologies targeting solid waste CS.
Graphene oxide dispersed multi-walled carbon nanotubes composite modified glassy carbon electrode (GO-MWNTs/GCE) was prepared and the GO-MWNTs/GCE was employed for the electrochemical determination ...of anticancer drug cisplatin. A pair of well-defined redox peak of cisplatin was observed at the GO-MWNTs/GCE in 0.05 M KCl solution (pH 7.4) and electrode process is adsorption- controlled. The result indicates that the GO-MWNTs composite materials can effectively improve the sensibility and performance of the electrode for cisplatin. Based on the GO-MWNTs/GCE, a differential pulse voltammetry (DPV) method for the determination of cisplatin was proposed. The analytical performance of the method was further evaluated in the presence of human 5% serum. A good linear relationship was obtained within the concentration range from 1.30 μM to 26.0 μM in the presence of 5% serum, with the linear regression equation Ipa (qA)= 345947c+3.2421 (r=0.9990). The detection limit for cisplatin in the presence of 5% human serum can reach to 0.113 μM.
Spinel LiMn2O4 cathode material was rapidly synthesized in 1h by solid-state combustion synthesis using metal carbonates as metal ion sources and glucose as a fuel. The effect of different amounts of ...glucose on the structure and electrochemical performance of as-prepared LiMn2O4 was investigated by X-ray diffraction (XRD), scanning electron micrographs (SEM), galvanostatic charge–discharge test, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). LiMn2O4 spinel was identified as the main crystalline phase with the presence of minor Mn3O4. The amount of glucose greatly affected the formation of Mn3O4. The optimal content of glucose was found to be 10wt%. Under this condition, the Mn3O4 peaks almost disappeared, and high-purity spinel LiMn2O4 was obtained. Its initial discharge specific capacity of was 125.9mAh/g, and discharge specific capacity retained at 105.2mAh/g after 40 cycles. The detail influence of glucose on the electrochemical activity, reversibility and cycling performance of LiMn2O4 was discussed.
One of the critical challenges to develop advanced lithium‐sulfur (Li‐S) batteries lies in exploring a high efficient stable sulfur cathode with robust conductive framework and high sulfur loading. ...Herein, a 3D flexible multifunctional hybrid is rationally constructed consisting of nitrogen‐doped carbon foam@CNTs decorated with ultrafine MgO nanoparticles for the use as advanced current collector. The dense carbon nanotubes uniformly wrapped on the carbon foam skeletons enhance the flexibility and build an interconnected conductive network for rapid ionic/electronic transport. In particular, a synergistic action of MgO nanoparticles and in situ N‐doping significantly suppresses the shuttling effect via enhanced chemisorption of lithium polysulfides. Owing to these merits, the as‐built electrode with an ultrahigh sulfur loading of 14.4 mg cm−2 manifests a high initial areal capacity of 10.4 mAh cm−2, still retains 8.8 mAh cm−2 (612 mAh g−1 in gravimetric capacity) over 50 cycles. The best cycling performance is achieved upon 800 cycles with an extremely low decay rate of 0.06% at 2 C. Furthermore, a flexible soft‐packaged Li‐S battery is readily assembled, which highlights stable electrochemical characteristics under bending and even folding. This cathode structural design may open up a potential avenue for practical application of high‐sulfur‐loading Li‐S batteries toward flexible energy‐storage devices.
A 3D, flexible, multifunctional hybrid comprised of nitrogen‐doped carbon foam@carbon nanotubes decorated with ultrafine MgO nanoparticles (CF@CNTs/MgO) is designed by a structural engineering strategy. This hybrid is used as the self‐supported current collector for high‐performance Li‐S batteries with high sulfur‐loading.
The Li1.02Ni0.05Mn1.93O4 cathode material exhibits a better rate capability than that of the LiNi0.05Mn1.95O4. Moreover, the Li1.02Ni0.05Mn1.93O4 shows the well-developed crystal structure with the ...(111), (110) and (100) crystal planes. The (111) crystal planes possess the minimum Mn dissolution and the (110) and (100) crystal planes are well consistent with the Li+ diffusion channel.
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Various Li-rich spinel Li1+xNi0.05Mn1.95-xO4 (0 ≤ x ≤ 0.10) cathode materials with a truncated octahedron were synthesized by a solution combustion method. The relationship of crystalline structure, particles morphology and electrochemical properties of the as-prepared samples was investigated via a series of physicochemical characterizations. The Li-Ni co-doping changes the lattice parameters and atomic configuration, whilst resulting in a contraction of unit cell dimension and giving rise to a variation of bond length. In this regard, the shrinkage of octahedral MnO6 provides a robust structure and the expansion of tetrahedral LiO4 facilitates a fast electrochemical process. Additionally, the resulted polyhedral Li1+xNi0.05Mn1.95-xO4 samples present the exposed (110), (100), and (111) crystal planes, which provide the favorable Li+ ions diffusion/transmission channel and alleviate Mn dissolution. Owing to these merits of polyhedral structure and Li-Ni co-doping, the optimized Li1.02Ni0.05Mn1.93O4 exhibits good electrochemical performance with high initial discharge capacity of 119.8, 107.1 and 97.9 mAh·g−1 at 1, 5 and 10 C, respectively. Even at a high current rate of 15 C, an excellent capacity retention of 91.7% is obtained after 1000 cycles, whilst the high temperature performance was also improved.
