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P2-layered metal oxide cathodes exhibit great promise for use in sodium ion batteries due to their unique two-dimensional tunnel structure, high energy density and high redox potential, etc. However, the inferior structural stability and irreversible phase change of P2-layered cathodes inhibit their development. The best effective strategies to improve their structural stability and sodium storage properties are via the optimization of the P2-layered tunnel structure and morphology by adjusting the Na+ contents, lithium substitution and rational element doping. Herein, the first sub-group element (Cu2+, Ag+ and Au+) doped Na0.5Li0.07Mn0.61Co0.16Ni0.16O2 cathodes were successfully prepared and systematically studied using operando X-ray powder diffraction (XRD), Rietveld refinement with corresponding Fourier electron cloud maps and the galvanostatic intermittent titration technique (GITT). These data indicate that the lattice parameters (a/b, c and V), energy barrier, and Na+ diffraction coefficient of sub-group element-doped Na0.5Li0.07Mn0.61Co0.16Ni0.16O2 cathodes are gradually improved in line with an increase in the sub-group element radii, which facilitate the kinetics of Na+ migration due to the synergistic effect between the valence and radius. Additionally, the structural stability and sodium storage mechanism of the optimized hybrid Na0.5Li0.07Mn0.6Co0.16Ni0.16Au0.01O2 electrode was revealed via operando XRD.

Summary Metal organic framework (MOF) derivatives have been extensively used as bifunctional oxygen electrocatalysts. However, the utilization of active sites is still not satisfactory owing to the sluggish mass transport within their narrow pore channels. Herein, interconnected macroporous channels were constructed inside MOFs-derived Co-Nx-C electrocatalyst to unblock the mass transfer barrier. The as-synthesized electrocatalyst exhibits a honeycomb-like morphology with highly exposed Co-Nx-C active sites on carbon frame. Owing to the interconnected ordered macropores throughout the electrocatalyst, these active sites can smoothly “exhale/inhale” reactants and products, enhancing the accessibility of active sites and the reaction kinetics. As a result, the honeycomb-like Co-Nx-C displayed a potential difference of 0.773 V between the oxygen evolution reaction potential at 10 mA cm−2 and the oxygen reduction reaction half-wave potential, much lower than that of bulk-Co-Nx-C (0.842 V). The rational modification on porosity makes such honeycomb-like MOF derivative an excellent bifunctional oxygen electrocatalyst in rechargeable Zn-air batteries., Graphical Abstract, Highlights • A deep-breathing oxygen electrocatalyst with highly dispersed active sites was built • Sculpturing ordered macropores in MOF derivatives enables fast mass transport • The honeycomb-like Co-Nx-C nanopolyhedron worked well in rechargeable Zn-air battery, Catalysis; Inorganic Materials; Electrochemical Energy Storage.

In this communication, in order to develop superior electrode materials for advanced energy storage devices, a new strategy is proposed and then verified by the (Si@MnO)@C/RGO anode material for lithium ion batteries. The core idea of this strategy is the use of a positive cycling trend (gradually increasing Li-storage capacities of the MnO-based constituent during cycling) to compensate the negative one (gradually decreasing capacities of the Si anode) to achieve ultralong cycling stability. As demonstrated in both half and full cells, the as-prepared (Si@MnO)@C/RGO nanocomposite exhibits superior Li-storage properties in terms of ultralong cycling stability (no obvious increase or decrease of capacity when cycled at 3 A g−1 after 1500 cycles) and excellent high-rate capabilities (delivering a capacity of ca. 540 mA h g−1 at a high current density of 8 A g−1) as well as a good full-cell performance. In addition, the structure of the electrodes is stable after 200 cycles. Such a strategy provides a new idea to develop superior electrode materials for next-generation energy storage devices with ultralong cycling stabilities.

Coaxial nanotubes are a significant class of nanoscale building blocks for advanced electrodes of secondary batteries. Herein, one-dimensional (1D) coaxial double nanotubes (DNTs) consisting of α-MnSe inner tubes and N-doped carbon (N–C) outer tubes (abbreviated as α-MnSe@N–C DNTs) are successfully prepared and are demonstrated to be promising anode material for Li-ion and Na-ion batteries (LIBs/NIBs). When used in LIBs, it was revealed by ex situ XRD/HRTEM studies and electrode kinetics that a new electrochemical α → β phase transition plays a crucial role in improving the cycling stability. As a result, the α-MnSe@N–C DNTs electrode delivers a high Li-storage capacity (800 mA h g−1 at 50 mA g−1), excellent rate capability (405 mA h g−1 at 14 A g−1) and ultra-long cycling stability (a high capacity retention of 87.2% even after 9000 cycles at 2 A g−1) with retained 1D morphology. In addition, the outer N–C nanotube can effectively protect the active α-MnSe inner nanotube to realize such outstanding electrochemical properties owing to the high electrical conductivity and particular 1D coaxial nanoarchitecture of the inner nanotube. Moreover, α-MnSe@N–C DNTs also exhibit excellent Li/Na-storage properties and full-cell performances when coupled with commercial LiFePO4 and LiNi0.6Co0.2Mn0.2O2 cathodes in LIBs as well as with the Na3V2(PO4)2O2F cathode in NIBs.

Sodium-ion batteries (SIBs) represent a promising alternative to lithium-ion batteries, owing to the much higher abundance and lower cost of sodium resources in comparison with lithium. However, the electrode materials of SIBs usually suffer from more severe issues, such as low specific capacity and poor cyclability, owing to the much larger Na+ diameter and drastic volumetric variations during sodiation/desodiation. Hence, it is still a huge challenge to develop superior electrode materials for reversible Na storage. In comparison with the crystalline materials conventionally used in batteries, amorphous ones may offer a more stable framework for the uptake of Na. To address these issues, a porous composite composed of amorphous Co2P and N,B-co-doped carbon (A-Co2P/CxNyBz-650) is prepared by controlling the annealing temperature at 650 °C after freeze-drying the precursors. As-prepared A-Co2P/CxNyBz-650 exhibits much better Na-storage properties in terms of higher Na-storage capacity, longer cycling stability, and excellent rate performance compared with the crystalline counterparts. These may benefit from the fact that the amorphous framework can provide easier Na+ accessibility and better strain accommodation, originating from volumetric variations during sodiation/desodiation. More importantly, the electrolyte for all of the electrochemical tests are NaPF6 based, which is more accessible for practical applications because of its higher safety compared with the commonly used NaClO4-based electrolyte.

Metallic antimony (Sb) is one promising candidate as anode material for sodium-ion batteries (SIBs) due to its high theoretical capacity of 660 mAh/g. However, the electrochemical formation of Na 3 Sb alloy makes it will suffer from tremendous volume variation during Na-uptake/release cycling and hence poor practical Na-storage properties. The incorporation of reduced graphene oxide (rGO) should be one effective strategy to overcome this issue. Herein, it is excitingly discovered that in-situ preparation micro/nanocomposite composed of Sb and rGO has played an effective role on improving Na-storage performance, especially fast energy storage and cycle life. The in-situ -prepared micro/nanocomposite (I-Sb/rGO) can deliver a superior capacity of 112 mAh/g even at an ultrahigh current density of 6 A/g compared to the ex-situ -prepared one (E-Sb/rGO). And it also exhibits outstanding cycle life with a residual capacity of 173 mAh/g after 150 cycles at current density of 0.5 A/g, much higher than that (36 mAh/g) of the ex-situ one. Those enhanced performance can be attributed to the advanced in-situ -prepared process.

As is well known, a gradual increase in capacity during cycling is a common phenomenon in previously reported oxide-based anodes for lithium-ion batteries. However, not only may this be superfluous for practical applications, but it may also imply the presence of some electrochemical instabilities and side reactions. To achieve ultrastable Li storage without such a gradual increase in capacity, the mechanism of this increase by using a MnO/graphene-based nanohybrid (MnO@C/RGO) as an example was comprehensively explored. Then, the gradual increase behavior of the specific capacity was effectively restrained by rationally optimizing the cutoff voltage, which resulted in the MnO@C/RGO electrode maintaining a nearly constant capacity during cycling at different current densities. Taking the high current density of 2 A g−1 as an example, there was no clear capacity change (increase/attenuation) even over 2000 cycles with stable coulombic efficiencies of around 99.7 %. This ultrastable Li-storage capability should mainly benefit from rational testing parameters and an optimal 3D conductive network. More importantly and interestingly, full cells were also assembled and tested by coupling MnO@C/RGO and commercial LiFePO4 as the anode and cathode materials, respectively. The full cells impressively exhibited superior rate performance and excellent cycling stability.

Dual-carbon enhanced Si-based composite (Si/C/G) has been prepared via employing the widely distributed, low-cost and environmentally friendly Diatomite mineral as silicon raw material. The preparation processes are very simple, non-toxic and easy to scale up. Electrochemical tests as anode material for lithium ion batteries (LIBs) demonstrate that this Si/C/G composite exhibits much improved Li-storage properties in terms of superior high-rate capabilities and excellent cycle stability compared to the pristine Si material as well as both single-carbon modified composites. Specifically for the Si/C/G composite, it can still deliver a high specific capacity of about 470 mAh g−1 at an ultrahigh current density of 5 A g−1, and exhibit a high capacity of 938 mAh g−1 at 0.1 A g−1 with excellent capacity retention in the following 300 cycles. The significantly enhanced Li-storage properties should be attributed to the co-existence of both highly conductive graphite and amorphous carbon in the Si/C/G composite. While the former can enhance the electrical conductivity of the obtained composite, the latter acts as the adhesives to connect the porous Si particulates and conductive graphite flakes to form robust and stable conductive network.

In recent years, graphene-incorporated micro-/nanocomposites represent one of the hottest developing directions for the composite materials. However, a large number of active nanoparticles (NPs) are still in the unprotected state in most constructed graphene-containing designs, which will seriously impair the effects of the graphene additives. Here, a fully protected Fe3O4-based micro-/nanocomposite (G/Fe3O4@C) is rationally developed by carbon-boxing the common graphene/Fe3O4 microparticulates (G/Fe3O4). The processes and results of full protection are tracked in detail and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and nitrogen absorption–desorption isotherms, as well as scanning and transition electron microscopy. When used as the anode for lithium-ion batteries, the fully protected G/Fe3O4@C exhibits the best lithium-storage properties in terms of the highest rate capabilities and the longest cycle life compared to the common G/Fe3O4 composites and commercial Fe3O4 products. These much improved properties are mainly attributed to its novel structural features including complete protection of active Fe3O4 nanoparticles by the surface carbon box, a robust conductive network composed of nitrogen-doped graphene nanosheets, ultra-small Fe3O4 NPs of 4–5 nm, abundant mesopores to accommodate the volume variation during cycling, and micrometer-sized secondary particles.

Among the transition metal oxides as anode materials for lithium ion batteries (LIBs), the MnO material should be the most promising one due to its many merits mainly relatively low voltage hysteresis. However, it still suffers from inferior rate capabilities and poor cycle life arising from kinetic limitations, drastic volume changes and severe agglomeration of active MnO particulates during cycling. In this paper, by integrating the typical strategies of improving the electrochemical properties of transition metal oxides, we had rationally designed and successfully prepared one superior MnO-based nanohybrid (MnO@C/RGO), in which carbon-coated MnO nanoparticles (MnO@C NPs) were electrically connected by three-dimensional conductive networks composed of flexible graphene nanosheets. Electrochemical tests demonstrated that, the MnO@C/RGO nanohybrid not only showed the best Li storage performance in comparison with the commercial MnO material, MnO@C NPs and carbon nanotube enhanced MnO@C NPs, but also exhibited much improved electrochemical properties compared with most of the previously reported MnO-based materials. The superior electrochemical properties of the MnO@C/RGO nanohybrid included a high specific capacity (up to 847 mA h g−1 at 80 mA g−1), excellent high-rate capabilities (for example, delivering 451 mA h g−1 at a very high current density of 7.6 A g−1) and long cycle life (800 cycles without capacity decay). More importantly, for the first time, we had achieved the discharging/charging of MnO-based materials without capacity increase even after 500 cycles by adjusting the voltage range, making the MnO@C/RGO nanohybrid more possible to be a really practical anode material for LIBs.

The enthalpies of dissolution of gemcitabine hydrochloride in 0.9 % normal saline (medical) and citric acid solution were measured using a microcalorimeter at 309.65 K under atmospheric pressure. The differential enthalpy $$ \left( {\Updelta_{\text{dif}} H_{\text{m}}^{{{\theta}}} } \right) $$ and molar enthalpy $$ \left( {\Updelta_{\text{sol}} H_{\text{m}}^{{{\theta}}} } \right) $$ of dissolution were determined, respectively. The corresponding kinetic equation described the dissolution were elucidated to be da/dt = 10−3.84(1 − a)0.92 and da/dt = 10−3.80(1 − a)1.21. Besides, the half-life, $$ \Updelta_{\text{sol}} H_{\text{m}}^{{{\theta}}} ,\;\Updelta_{\text{sol}} G_{\text{m}}^{{{\theta}}} $$ and $$ \Updelta_{\text{sol}} S_{\text{m}}^{{{\theta}}} $$ of the dissolution were also obtained. Obviously, it will provide a simple and reliable method for the clinical application of gemcitabine hydrochloride.

The dissolution enthalpy of Cisplatin and Etoposide in the appropriate solvent were measured by RD496-2000 microcalorimeter under the conditions of atmospheric pressure and 309.65 K. The differential heat and the integral heat of the process are obtained, thereby establishing the relationship between the heat and the amount of solute, knowing that the dissolution process is the pseudo-first order reaction. In turn, the half-life, △solHm, △solGm, △solSm are also can obtained.

Although graphene oxide (GO) has large interlayer spacing, it is still inappropriate to use it as an anode for sodium-ion batteries (SIBs) because of the existence of H-bonding between the layers and ultralow electrical conductivity which impedes the Na(+) and e(-) transformation. To solve these issues, chemical, thermal, and electrochemical procedures are traditionally employed to reduce GO nanosheets. However, these strategies are still unscalable, consume high amounts of energy, and are expensive for practical application. Here, for the first time, we describe the superior Na storage of unreduced GO by a simple and scalable alkali-metal-ion (Li(+) , Na(+) , K(+) )-functionalized process. The various alkali metals ions, connecting with the oxygen on GO, have played different effects on morphology, porosity, degree of disorder, and electrical conductivity, which are crucial for Na-storage capabilities. Electrochemical tests demonstrated that sodium-ion-functionalized GO (GNa) has shown outstanding Na-storage performance in terms of excellent rate capability and long-term cycle life (110 mAh g(-1) after 600 cycles at 1 A g(-1) ) owing to its high BET area, appropriate mesopore, high degree of disorder, and improved electrical conductivity. Theoretical calculations were performed using the generalized gradient approximation (GGA) to further study the Na-storage capabilities of functionalized GO. These calculations have indicated that the Na-O bond has the lowest binding energy, which is beneficial to insertion/extraction of the sodium ion, hence the GNa has shown the best Na-storage properties among all comparatives functionalized by other alkali metal ions.