Strategy for enhanced performance of silicon nanoparticle anodes for lithium-ion batteries

The modification of silicon nanoparticles for lithium-ion battery anode materials has been a hot exploration subject in light of their excellent volume buffering performance. However, huge volume expansion leads to an unstable solid electrolyte interface (SEI) layer on the surface of the silicon anode material, resulting in short cell cycle life, which is an important factor limiting the application of silicon nanoparticles. Herein, a dual protection strategy to improve the cycling stability of commercial silicon nanoparticles is demonstrated. Specifically, the Si/s-C@TiO₂ composite was produced by the hydrothermal method to achieve the embedding of commercial silicon nanoparticles in spherical carbon and the coating of the amorphous TiO₂ shell on the outer surface. Buffering of silicon nanoparticle volume expansion by spherical carbon and also the stabilization of the TiO₂ shell with high mechanical strength on the surface constructed a stable outer surface SEI layer of the new Si/s-C@TiO₂ electrode during longer cycling. In addition, the spherical carbon and lithiated TiO₂ further enhanced the electronic and ionic conductivity of the composite. Electrochemical measurements showed that the Si/s-C@TiO₂ composite exhibited excellent lithium storage performance (780 mA h g⁻¹ after 100 cycles at a current density of 0.2 A g⁻¹ with a coulombic efficiency of 99%). Our strategy offers new ideas for the production of high stability and high-performance anode materials for lithium-ion batteries.

The rational structural design of the spherical carbon and TiO₂ shell results in a significant improvement in the lithium storage performance of commercial silicon nanoparticles, particularly in terms of cycling stability.     

Dimethylacrylamide,a novel electrolyte additive,can improve the electrochemical performances of silicon anodes in lithium-ion batteries

To enhance the electrochemical properties of silicon anodes in lithium-ion batteries, dimethylacrylamide (DMAA) was selected as a novel electrolyte additive. The addition of 2.5 wt% DMAA to 1.0 M LiPF₆/EC : DMC : DEC : FEC (3 : 3 : 3 : 1 weight ratio) electrolyte significantly enhanced the electrochemical properties of the silicon anode including the first coulombic efficiency, rate performance and cycle performance. The solid electrolyte interphase (SEI) layers developed on the silicon anode in different electrolytes were investigated by a combination of electrochemical and spectroscopic studies. The improved electrochemical performances of the Si anode were ascribed to the effective passivation of DMAA on the silicon anode. The addition of DMAA helped develop a uniform SEI layer, which prevented side reactions at the interface of silicon and electrolyte.

To enhance the electrochemical properties of silicon anodes in lithium-ion batteries, dimethylacrylamide (DMAA) was selected as a novel electrolyte additive.     

CuFeO2–NiFe2O4 hybrid electrode for lithium-ion batteries with ultra-stable electrochemical performance

Stable electrode materials with guaranteed long-term cyclability are indispensable for advanced lithium-ion batteries. Recently, delafossite CuFeO₂ has received considerable attention, due to its relative structural integrity and cycling stability. Nevertheless, the low conductivity of delafossite and its relatively low theoretical capacity prevent its use as feasible electrodes for next-generation batteries that require higher reversible capacities. In this work, we suggest a simple and straightforward approach to prepare CuFeO₂–NiFe₂O₄ by introducing Ni precursor into Cu and Fe precursor to form NiFe₂O₄, which exhibits higher capacity but suffers from capacity fading, through sol–gel process and subsequent heat treatments. The presence of both NiFe₂O₄ and CuFeO₂ is apparent, and the heterostructure arising from the formation of NiFe₂O₄ within CuFeO₂ renders some synergistic effects between the two active materials. As a result, the CuFeO₂–NiFe₂O₄ hybrid sample exhibits excellent cycling stability and improved rate capability, and can deliver stable electrochemical performance for 800 cycles at a current density of 5.0 A g⁻¹. This work is an early report on introducing a foreign element into the sol–gel process to fabricate heterostructures as electrodes for batteries, which open up various research opportunities in the near future.

Novel NiFe₂O₄–CuFeO₂ heterostructures were synthesized by sol–gel process and subsequent heat treatments, which exhibit excellent long-term high-rate cyclability.     

Rapid fabrication of porous silicon/carbon microtube composites as anode materials for lithium-ion batteries

Herein, we present a simple and rapid method to synthesize porous silicon/carbon microtube composites (PoSi/CMTs) by adopting a unique configuration of acid etching solution. The CMTs can act as both conductive agent and buffer for Si volume change during the charge and discharge process. The highly reversible capacity and excellent rate capability can be ascribed to the structure, where porous silicon powders are wrapped by a network of interwoven carbon microtubes. The composites show specific capacities of more than 1712 mA h g⁻¹ at a current density of 100 mA g⁻¹, 1566 mA h g⁻¹ at 200 mA g⁻¹, 1407 mA h g⁻¹ at 400 mA g⁻¹, 1177 mA h g⁻¹ at 800 mA g⁻¹, 1107 mA h g⁻¹ at 1000 mA g⁻¹, 798 mA hg⁻¹ at 2000 mA g⁻¹, and 581 mA h g⁻¹ at 3000 mA g⁻¹ and maintain a value of 1127 mA h g⁻¹ after 100 cycles at a current density of 200 mA g⁻¹. Electrochemical impedance spectroscopy (EIS) measurements prove that charge transfer resistance of PoSi/CMT composites is smaller than that of pure PoSi. In this study, we propose a quick, economical and feasible method to prepare silicon-based anode materials for lithium-ion batteries.

We added additives to the acid etching solution and prepared the silicon/carbon microtubes composites using a simple and fast method.     

Synergetic effect of Na-doping and carbon coating on the electrochemical performances of Li3−xNaxV2(PO4)3/C as cathode for lithium-ion batteries

Carbon coated Li_3−xNa_xV₂(PO₄)₃/C (x = 0.04, 0.06, 0.10, 0.12, 0.18) cathode materials for lithium-ion batteries were synthesized via a simple carbothermal reduction reaction route using methyl orange as the reducing agent, which also acted as the Na and carbon sources. The influence of various Na-doping levels on the structure and electrochemical performance of the Li_3−xNa_xV₂(PO₄)₃/C composites was investigated. The valence state of vanadium, the form of residual carbon and the overall morphology of the Li_2.90Na_0.10V₂(PO₄)₃/C, which showed the highest initial specific discharge capacity of 128 mA h g⁻¹ at the current density of 0.1C (1C = 132 mA g⁻¹) among this series of composites, were further examined by X-ray photoelectron spectroscopy, Raman spectroscopy, scanning electron microscopy and high-resolution transmission electron microscopy, respectively. The results indicated that a well crystallized structure of Na-doped Li_2.90Na_0.10V₂(PO₄)₃ coated by a carbon matrix is obtained. In the further electrochemical measurements, the Li_2.90Na_0.10V₂(PO₄)₃/C cathode material shows superior discharge capacities of 124, 118, 113, 106 and 98 mA h g⁻¹ at 0.3, 0.5, 1, 2 and 5C, respectively. High capacity retention of 97% was obtained after 1100 cycles in long-term cyclic performance tests at 5C. The reason for such a promising electrochemical performance of the as-prepared Li_2.90Na_0.10V₂(PO₄)₃/C has also been explored, which revealed that the synergetic effect of the Na-doping and carbon coating provide enlarged Li⁺ diffusion channels and the increased electronic conductivity.

Carbon coated Li_3−xNa_xV₂(PO₄)₃/C (x = 0.04, 0.06, 0.10, 0.12, 0.18) cathode materials for lithium-ion batteries were synthesized via a simple carbothermal reduction reaction route using methyl orange as the reducing agent.     

The electrochemical performance of fluorinated ketjenblack as a cathode for lithium/fluorinated carbon batteries

The inferior rate capacity of lithium/fluorinated carbon (Li/CF_x) batteries limits their application in the field, requiring large discharge current and high power density. Herein, we report a novel type of fluorinated carbon with superior performance through gas-phase fluorination of ketjenblack. The investigation shows that the F/C ratio of the fluorinated ketjenblack (FKB) increases with the fluorination temperature, whereas the discharge voltage decreases due to the lowered content of semi-ionic C–F bonds. Accordingly, a suitable fluorination temperature of 520 °C was selected, under which the product exhibits the largest specific capacity of 924.6 mA h g⁻¹ with discharge potential exceeding 3.1 V (vs. Li/Li⁺) and the highest energy density of 2544 W h kg⁻¹ with power density of 27 493 W kg⁻¹. This energy density is higher than the theoretical energy density of commercial fluorinated graphite (2180 W h kg⁻¹). In addition, the sample delivers good rate capability demonstrated by a specific capacity retention ratio of 79.5% even at a current density of 20C. Therefore, the FKB material may have very promising practical applications in lithium primary batteries.

Fluorinated kejtenblack as the cathode of Li/CF_x batteries exhibits excellent energy density and power density with high rate capability.     

A self-assembled silicon/phenolic resin-based carbon core–shell nanocomposite as an anode material for lithium-ion batteries

Silicon, with advantages such as high theoretical capacity and relatively low working potential, has been regarded as promising when it is used for lithium-ion battery anodes. However, its practical application is impeded by the intrinsic low electrical conductivity and the dramatic volume change during the lithiation/delithiation process, which leads to a rapid capacity fading of the electrode. In this regard, we design silicon nanoparticles homogeneously coated with a phenolic resin-based carbon layer as a core–shell nanocomposite via a facile self-assembly method followed by carbonization. The surrounding carbon shell, confirmed by transmission electron microscopy and Raman spectroscopy, is not only beneficial to the formation of a stable solid electrolyte interface film, but the electrical conductivity of the electrode is also enhanced. A high and stable specific capacity of nearly 1000 mA h g⁻¹ is achieved at C/3 after 200 cycles with a coulombic efficiency of >99.6%. The entire synthesis process is quite simple and easy to scale up, thus having great potential for commercial applications.

A self-assembled silicon/phenolic resin-based carbon core–shell nanocomposite is reported, which exhibits a high and stable reversible capacity and good rate capability.     

Role of polyvinylpyrrolidone in the electrochemical performance of Li2MnO3 cathode for lithium-ion batteries

While Li₂MnO₃ as an over-lithiated layered oxide (OLO) shows a significantly high reversible capacity of 250 mA h g⁻¹ in lithium-ion batteries (LIBs), it has critical issues of poor cycling performance and deteriorated high rate performance. In this study, modified OLO cathode materials for improved LIB performance were obtained by heating the as-prepared OLO at different temperatures (400, 500, and 600 °C) in the presence of polyvinylpyrrolidone (PVP) under an N₂ atmosphere. Compared to the as-prepared OLO, the OLO sample heated at 500 °C with PVP exhibited a high initial discharge capacity of 206 mA h g⁻¹ and high rate capability of 111 mA h g⁻¹ at 100 mA g⁻¹. The superior performance of the OLO sample heated at 500 °C with PVP is attributed to an improved electronic conductivity and Li⁺ ionic motion, resulting from the formation of the graphitic carbon structure and increased Mn³⁺ ratio during the decomposition of PVP.

The modified OLO cathode materials for improved LIB performance were obtained by heating the as-prepared OLO in the presence of polyvinylpyrrolidone (PVP) under an N₂ atmosphere.     

Improving the electrochemical performance of a natural molybdenite/N-doped graphene composite anode for lithium-ion batteries via short-time microwave irradiation

In the present work, low-cost natural molybdenite was used to make a MoS₂/N-doped graphene composite through coulombic attraction with the aid of (3-aminopropyl)-triethoxysilane and the electrochemical performance was greatly improved by solvent-free microwave irradiation for tens of seconds. The characterization results indicated that most (3-aminopropyl)-triethoxysilane can decompose and release N atoms to further improve the N-doping degree in NG during the microwave irradiation. In addition, the surface groups of N-doped graphene were removed and the particle size of MoS₂ was greatly decreased after the microwave irradiation. As a result, the composite electrode prepared with microwave irradiation exhibited a better rate performance (1077.3 mA h g⁻¹ at 0.1C and 638 mA h g⁻¹ at 2C) than the sample prepared without microwave irradiation (1013.6 mA h g⁻¹ at 0.1C and 459.1 mA h g⁻¹ at 2C). Therefore, the present results suggest that solvent-free microwave irradiation is an effective way to improve the electrochemical properties of MoS₂/N-doped graphene composite electrodes. This work also demonstrates that natural molybdenite is a promising low-cost anode material for lithium-ion batteries.

In this work, low-cost natural molybdenite was used to make a MoS₂/N-doped graphene composite with the aid of (3-aminopropyl)-triethoxysilane and the electrochemical performance was greatly improved by solvent-free microwave irradiation.     

Investigation of the soft carbon microstructure in silicon/carbon anodes for superior lithium storage

It is essential to consider the controllable microstructure of soft carbon and its enhancement effect on the electrochemical performance of silicon (Si) active materials. In this study, a series of Si@mesocarbon microbead (Si@MCMB) composites were prepared using mesophase pitch as the soft carbon source to coat nano-Si. The results showed that the ordered carbon layer stacking of soft carbon increased slightly with increasing heat treatment temperature in the range of 800–1400 °C. The Si@MCMB composites at higher temperature had a turbostratic carbon layer texture with rich porosity and smaller specific surface area, and had good cycle stability and high rate performance. These results highlighted that the co-existing structure of turbostratic carbon arrays with abundant porosity from soft carbon, provided the electron/ion transfer channels, underwent Si alloy volume change and enhanced the mechanical stability. Importantly, the relationship between the capacity retention rate of the Si@MCMB anodes and the microstructural characteristics (carbon layer and porosity) of soft carbon was established, which provided effective guidance for the design of high-performance silicon/carbon (Si/C) anode materials.

It is essential to consider the controllable microstructure of soft carbon and its enhancement effect on the electrochemical performance of silicon (Si) active materials.     

Degradation of hybrid material l,d-PLA : 5CB : SWCN under the influence of neutral,acidic, and alkaline environments

The aim of the study was to investigate the influence of the environment''s pH on the degradation of the layers of the ternary composite l,d-PLA : 5CB : SWCN (10 : 1 : 0.5, w/w/w), where l,d-PLA (poly(lactic acid)) is a biodegradable polymer, 5CB is a well-known liquid crystal (4′-pentyl-4-biphenylcarbonitrile), and SWCN are single-walled carbon nanotubes. For this purpose, the samples were stored in air, distilled water, and solutions of 0.1 M NaOH and 0.1 M HCl, for up to 62 days. Using differential scanning calorimetry, atomic force microscopy, and infra-red spectroscopy methods it was observed that for both neat l,d-PLA and composite layers there was a poor degradation process after the storage under standard air conditions, distilled water, and 0.1 M HCl solution, while the erosion of the surface layer kept in 0.1 M NaOH solution was revealed just after 6 days. The longer storage in 0.1 M NaOH solution resulted in complete degradation of the l,d-PLA polymer layer, while the composite layer survived for up to 62 days. The solubilization of the polymeric l,d-PLA matrix in the composite after 62 days was so severe that it resulted in the vanishing of thermal effects on the DSC curve except for one that was probably connected with the glass transition of the residual quantity of the polymer that remained in the layer or the isotropisation of 5CB. As a result, we have shown that admixtures of 5CB and SWCN accelerate the degradation of l,d-PLA in the composite layer due to the hydrophilic/hydrophobic interface in the layer and act as plasticizers. The mechanism of the degradation process is also discussed.

We have shown that admixtures of 5CB and SWCN accelerate the degradation of l,d-PLA in the composite layer due to hydrophilic/hydrophobic interface in the layer and act as plasticizers. The mechanism of the degradation process is also discussed.     

Role of Al-doping with different sites upon the structure and electrochemical performance of spherical LiNi0.5Mn1.5O4 cathode materials for lithium-ion batteries

Al-doped spinel LiNi_0.5Mn_1.5O₄ materials with different sites and contents were synthesized by rapid precipitation combined with hydrothermal treatment and calcination. The roles of Al on structural stability and electrochemical performance were studied by utilizing a series of techniques. XRD patterns indicated lower ion diffusion and no impure phased in doped samples. FT-IR and CV results reveal that Al-doped materials possess a Fd$\bar{3}$m space group with increased disorder and increasing amounts of Mn³⁺. SEM and TEM equipped with EDS were used to characterize the regular morphology accompanied by a complete crystal structure and homogeneous distribution of elements. The Al content at the Ni, Mn, and Ni/Mn sites was optimized to be 5%, 3% and 5% (in total), respectively. The cycling stability was considerably enhanced at an ambient temperature (25 °C) and high temperature (55 °C). A typical Al dual-doped sample at Ni/Mn sites with 5% content delivered a reversible capacity of 113.5 mA h g⁻¹ after 200 cycles at 0.5C. The discharge capacity at 5, 10 and 20C was 127.3, 125.5 and 123.1 mA h g⁻¹, respectively. The discharge capacity remained at 126 mA h g⁻¹ after 50 cycles (55 °C, 0.5C). Subsequent EIS and analytical results of the cycled electrode showed improved structural stability with a lower resistance, stable cathode/electrolyte interface, and reduced dissolution of Mn. These data further demonstrated the feasibility and reliability of preparing high-performance spinel LiNi_0.5Mn_1.5O₄ cathode materials by doping with a suitable amount of Al.

Al-doped spinel LiNi_0.5Mn_1.5O₄ materials with different sites and contents were synthesized by rapid precipitation combined with hydrothermal treatment and calcination.     

Effect of Ti3C2Tx–PEDOT:PSS modified-separators on the electrochemical performance of Li–S batteries

Lithium–sulfur (Li–S) batteries have attracted much attention due to their high theoretical energy density, environmental friendliness, and low cost. However, the practical application of Li–S batteries is impeded by a severe shuttle effect. Using polar and conductive materials to prepare a modified separator as the second collector is an effective strategy to solve the shuttle effect. Herein, a Ti₃C₂T_x–PEDOT:PSS hybrid for modifying PP separators is successfully fabricated. In this hybrid, PEDOT:PSS can effectively prevent Ti₃C₂T_x nanosheets from restacking and enhance the electrical conductivity of Li–S batteries, thereby promoting fast Li⁺/electron transport and improving the sulfur utilization. Meanwhile, the introduction of Ti₃C₂T_x–PEDOT:PSS makes Ti₃C₂T_x nanosheets effectively anchor polysulfide, thus inhibiting the shuttle effect. As a result, Li–S cells with Ti₃C₂T_x–PEDOT:PSS modified-separators exhibit superior performances, including a high discharge capacity of 1241.4 mA h g⁻¹ at 0.2C, a long cycling stability, and a low decay rate of 0.030% per cycle at 0.5C for 1000 cycles.

Lithium–sulfur (Li–S) batteries have attracted much attention due to their high theoretical energy density, environmental friendliness, and low cost.     

The effect of graphitization degree of carbonaceous material on the electrochemical performance for aluminum-ion batteries

Aluminum-ion batteries are currently regarded as the most promising energy storage batteries. The recent development of aluminum-ion batteries has been greatly promoted based on the use of graphitic carbon materials as a positive electrode. However, it remains unclear whether all carbonaceous materials can achieve excellent electrochemical behaviour similar to graphite. In this study, the correlation between the graphitization degree and capacity of a graphite electrode is systematically investigated for aluminum-ion batteries. The results show that the higher the graphitization degree, the larger the charge/discharge capacity and the better the cycling stability. Moreover, graphite nanoflakes with the highest graphitization degree deliver an initial discharge capacity of 66.5 mA h g⁻¹ at a current density of 100 mA g⁻¹, eventually retaining 66.3 mA h g⁻¹ after 100 cycles with a coulombic efficiency of 96.1% and capacity retention of 99.7%, exhibiting an ultra-stable cycling performance. More importantly, it can be concluded that the discharge capacity of different kinds of graphite materials can be predicted by determining the graphitization degree.

The discharge capacity of graphitic carbon from non-graphitizable carbon strongly depends on the graphitization degree when used for aluminum-ion batteries.     

Improving the electrochemical performance of cathode composites using different sized solid electrolytes for all solid-state lithium batteries

We studied the efficiency of different particle-sized sulfide solid electrolyte-based cathode composites. First, we prepared the Li₇P₂S₈I solid electrolytes with different particle sizes through a high energy ball milling process and solution method. The structural details of the prepared solid electrolytes were studied by powder X-ray diffraction. The surface morphologies and particle size of the electrolytes were studied by field emission electron microscopy. The ionic conductivity of the prepared solid electrolytes was studied by the electrochemical impedance spectroscopy technique. Finally, we have prepared a LiNi_0.8Co_0.1Mn_0.1O₂ (NCM 811) based cathode composite and studied the electrochemical performance of the fabricated all-solid-state lithium batteries. The mixed particle-sized solid electrolyte-based cathode composite exhibited higher specific capacitance (127.2 mA h g⁻¹) than the uniform-sized solid electrolyte-based cathode composite (117.1 mA h g⁻¹). The electrochemical analysis confirmed that the sulfide solid electrolytes with mixed particle size exhibited better electrochemical performance.

Improving the electrochemical performance of a cathode composite using different sized solid electrolytes for all-solid-state lithium batteries.     

Controlled sol–gel synthesis of oxygen sensing CdO : ZnO hexagonal particles for different annealing temperatures

CdO : ZnO hexagonal particles were synthesized by a sol–gel precipitation method at different annealing temperatures. A mixed crystal phase of cubic and wurtzite structures was observed from X-ray diffraction patterns. The micrographs showed hexagonal shapes of the CdO : ZnO nanocomposites particles. The energy dispersive X-ray spectroscopy mapping images showed a uniform distribution of the Cd and Zn. The CdO : ZnO nanocomposite pallet annealed at 550 °C has an electrical resistance of 0.366 kΩ at room temperature. The nanocomposites showed an excellent sensing response against oxygen gas with a sensing response of 47% at 200 °C for the CdO : ZnO particles annealed at 550 °C. The sensor response and recovery times were found to be 43s and 45s, respectively. The sensor response was due to the sorption of oxygen ions on the surfaces of the CdO : ZnO hexagonal particles.

CdO : ZnO hexagonal particles were synthesized by a sol–gel precipitation method at different annealing temperatures.     

Improved electrochemical performance and solid electrolyte interphase properties of electrolytes based on lithium bis(fluorosulfonyl)imide for high content silicon anodes

Electrodes containing 60 wt% micron-sized silicon were investigated with electrolytes containing carbonate solvents and either LiPF₆ or lithium bis(fluorosulfonyl)imide (LiFSI) salt. The electrodes showed improved performance, with respect to capacity, cycling stability, rate performance, electrode resistance and cycle life with the LiFSI salt, attributed to differences in the solid electrolyte interphase (SEI). Through impedance spectroscopy, cross sectional analysis using transmission electron microscopy (TEM) and focused ion beam (FIB) in combination with scanning electron microscopy (SEM), and electrode surface characterization by X-ray photoelectron spectroscopy (XPS), differences in electrode morphological changes, SEI composition and local distribution of SEI components were investigated. The SEI formed with LiFSI has a thin, inner, primarily inorganic layer, and an outer layer dominated by organic components. This SEI appeared more homogeneous and stable, more flexible and with a lower resistivity than the SEI formed in LiPF₆ electrolyte. The SEI formed in the LiPF₆ electrolyte appears to be less passivating and less flexible, with a higher resistance, and with higher capacitance values, indicative of a higher interfacial surface area. Cycling in LiPF₆ electrolyte also resulted in incomplete lithiation of silicon particles, attributed to the inhomogeneous SEI formed. In contrast to LiFSI, where LiF was present in small grains in-between the silicon particles, clusters of LiF were observed around the carbon black for the LiPF₆ electrolyte.

Lithiation of silicon in an LiFSI electrolyte results in a bilayer SEI, with an inner, inorganic layer, and an outer, organic. This SEI is more conductive, flexible and homogeneous compared to the SEI formed in an LiPF₆ electrolyte.     

A Role for Endogenous Transforming Growth Factor β1 in Langerhans Cell Biology: The Skin of Transforming Growth Factor β1 Null Mice Is Devoid of Epidermal Langerhans Cells

Transforming growth factor β1 (TGF-β1) regulates leukocytes and epithelial cells. To determine whether the pleiotropic effects of TGF-β1, a cytokine that is produced by both keratinocytes and Langerhans cells (LC), extend to epidermal leukocytes, we characterized LC (the epidermal contingent of the dendritic cell [DC] lineage) and dendritic epidermal T cells (DETC) in TGF-β1 null (TGF-β1 −/−) mice. I-A⁺ LC were not detected in epidermal cell suspensions or epidermal sheets prepared from TGF-β1 −/− mice, and epidermal cell suspensions were devoid of allostimulatory activity. In contrast, TCR-γδ⁺ DETC were normal in number and appearance in TGF-β1 −/− mice and, importantly, DETC represented the only leukocytes in the epidermis. Immunolocalization studies revealed CD11c⁺ DC in lymph nodes from TGF-β1 −/− mice, although gp40⁺ DC were absent. Treatment of TGF-β1 −/− mice with rapamycin abrogated the characteristic inflammatory wasting syndrome and prolonged survival indefinitely, but did not result in population of the epidermis with LC. Thus, the LC abnormality in TGF-β1 −/− mice is not a consequence of inflammation in skin or other organs, and LC development is not simply delayed in these animals. We conclude that endogenous TGF-β1 is essential for normal murine LC development or epidermal localization.     

Surface chemical functionality of carbon dots: influence on the structure and energy storage performance of the layered double hydroxide

As a kind of zero-dimensional material, carbon dots (CDs) have become a kind of promising novel material due to their incomparable unique physical and chemical properties. Despite the optical properties of CDs being widely studied, their surface chemical functions are rarely reported. Here we propose an interesting insight into the important role of surface chemical properties of CDs in adjusting the structure of the layered double hydroxide (LDH) and its energy storage performance. It was demonstrated that CDs with positive charge (p-CDs) not only reduce the size of the flower-like LDH through affecting the growth of LDH sheets, but also act as a structure stabilizer. After calcination, the layered double oxide (LDO) maintained the morphology of the LDH and prevented the stacking of layers. And the superiority of the composite in lithium-ion batteries (LIBs) was demonstrated. When used as an anode of LIBs, composites possess outstanding specific capacity, cycle stability and rate performance. It presents the discharge capacity of 1182 mA h g⁻¹ and capacity retention of 94% at the current density of 100 mA g⁻¹ after 100 cycles. Our work demonstrates the important chemical functions of CDs and expands their future applications.

As a kind of zero-dimensional material, carbon dots (CDs) have become a kind of promising novel material due to their incomparable unique physical and chemical properties.     

Rational construction of yolk–shell CoP/N,P co-doped mesoporous carbon nanowires as anodes for ultralong cycle life sodium-ion batteries

Owing to the natural abundance and low-cost of sodium, sodium-ion batteries offer advantages for next-generation portable electronic devices and smart grids. However, the development of anode materials with long cycle life and high reversible capacity is still a great challenge. Herein, we report a yolk–shell structure composed of N,P co-doped carbon as the shell and CoP nanowires as the yolk (YS–CoP@NPC) for a hierarchically nanoarchitectured anode for improved sodium storage performance. Benefitting from the 1D hollow structure, the YS–CoP@NPC electrode exhibits an excellent cycling stability with a reversibly capacity of 211.5 mA h g⁻¹ at 2 A g⁻¹ after 1000 cycles for sodium storage. In-depth characterization by ex situ X-ray photoelectron spectroscopy and work function analysis revealed that the enhanced sodium storage property of YS–CoP@NPC might be attributed to the stable solid electrolyte interphase film, high electronic conductivity and better Na⁺ diffusion kinetics.

Owing to the natural abundance and low-cost of sodium, sodium-ion batteries offer advantages for next-generation portable electronic devices and smart grids.