Fire-Retardant, Stable-Cycling and High-Safety Sodium Ion Battery.

The safety of energy storage equipment has always been a stumbling block to the development of battery, and sodium ion battery is no exception. However, as an ultimate solution, the use of non-flammable electrolyte is susceptible to the side effects, and its poor compatibility with electrode, causing failure of batteries. Here, we report a non-flammable electrolyte design to achieve high-performance sodium ion battery, which resolves the dilemma via regulating the solvation structure of electrolyte by hydrogen bonds and optimizing the electrode-electrolyte interphase. The reported non-flammable electrolyte allows stable charge-discharge cycling of both sodium vanadium phosphate@hard carbon and Prussian blue@hard carbon full pouch cell for more than 120 cycles with a capacity retention of >85 % and high cycling Coulombic efficiency (99.7 %).

A Single Electronic Tattoo for Multisensory Integration.

Wearable electronics are garnering growing interest in various emerging fields including intelligent sensors, artificial limbs, and human-machine interfaces. A remaining challenge is to develop multisensory devices that can conformally adhere to the skin even during dynamic-moving environments. Here, a single electronic tattoo (E-tattoo) based on a mixed-dimensional matrix network, which integrates two-dimensional  MXene nanosheets and one-dimensional cellulose nanofibers/Ag nanowires, is presented for multisensory integration. The multidimensional configurations endow the E-tattoo with excellent multifunctional sensing capabilities including temperature, humidity, in-plane strain, proximity, and material identification. In addition, benefiting from the satisfactory rheology of hybrid inks, the E-tattoos are able to be fabricated through multiple facile strategies including direct writing, stamping, screen printing, and three-dimensional printing on various hard/soft substrates. Especially, the E-tattoo with excellent triboelectric properties also can serve as a power source for activating small electronic devices. It is believed that these skin-conformal E-tattoo systems can provide a promising platform for next-generation wearable and epidermal electronics.

Achieving All-Plateau and High-Capacity Sodium Insertion in Topological Graphitized Carbon.

Hard carbon anodes with all-plateau capacities below 0.1 V are prerequisites to achieve high-energy-density sodium-ion storage, which holds promise for future sustainable energy technologies. However, challenges in removing defects and improving the insertion of sodium ions head off the development of hard carbon to achieve this goal. Herein, a highly cross-linked topological graphitized carbon using biomass corn cobs through a two-step rapid thermal-annealing strategy is reported. The topological graphitized carbon constructed with long-range graphene nanoribbons and cavities/tunnels provides a multidirectional insertion of sodium ions whilst eliminating defects to absorb sodium ions at the high voltage region. Evidence from advanced techniques including in situ XRD, in situ Raman, and in situ/ex situ transmission electron microscopy (TEM) indicates that the sodium ions' insertion and Na cluster formation occurred between curved topological graphite layers and in the topological cavity of adjacent graphite band entanglements. The reported topological insertion mechanism enables outstanding battery performance with a single full low-voltage plateau capacity of 290 mAh g-1 , which is almost 97% of the total capacity.

High-Voltage, Highly Reversible Sodium Batteries Enabled by Fluorine-Rich Electrode/Electrolyte Interphases.

High energy density and long-term cycling stability are crucial factors for the commercialization of sodium batteries in large scale. In this regard, cathode materials that can operate at high voltage have attracted great interest owing to their high energy density. However, traditional electrolytes cannot be used in high-voltage sodium batteries due to their limited oxidative stability. Therefore, there is a great challenge to develop appropriate electrolytes for high-voltage cathode materials. Herein, a diluted fluoroethylene carbonate (FEC)-based electrolyte (1 m NaPF6 in FEC/DMC = 2/8 by volume) is designed for Na4 Co3 (PO4 )2 P2 O7 (NCPP) cathode with a high operation voltage of 4.7 V to achieve superior electrochemical performance with a capacity retention of 90.10% after 500 cycles at 0.5 C and capacity retention of 89.99% after 1000 cycles at 1 C. The excellent electrochemical performance of the NCPP||Na cells can be attributed to the formation of inorganic and robust NaF-rich cathode electrolyte interphase and F-rich solid electrolyte interface on high voltage NCPP cathode and Na metal anode, respectively. This work points out a very promising strategy to develop high-voltage sodium batteries toward practical applications.

Na1.51 Fe[Fe(CN)6 ]0.87 ·1.83H2 O Hollow Nanospheres via Non-Aqueous Ball-Milling Route to Achieve High Initial Coulombic Efficiency and High Rate Capability in Sodium-Ion Batteries.

Prussian blue analogues (PBAs) have attracted extensive attention as cathode materials in sodium-ion batteries (SIBs) due to their low cost, high theoretical capacity, and facile synthesis process. However, it is of great challenge to control the crystal vacancies and interstitial water formed during the aqueous co-precipitation method, which are also the key factors in determining the electrochemical performance. Herein, an antioxidant and chelating agent co-assisted non-aqueous ball-milling method to generate highly-crystallized Na2- x Fe[Fe(CN)6 ]y with hollow structure is proposed by suppressing the speed and space of crystal growth. The as-prepared Na2- x Fe[Fe(CN)6 ]y hollow nanospheres show low vacancies and interstitial water content, leading to a high sodium content. As a result, the Na-rich Na1.51 Fe[Fe(CN)6 ]0.87 ·1.83H2 O hollow nanospheres exhibit a high initial Coulombic efficiency, excellent cycling stability, and rate performance via a highly reversible two-phase transition reaction confirmed by in situ X-ray diffraction. It delivers a specific capacity of 124.2 mAh g-1 at 17 mA g-1 , presenting ultra-high rate capability (84.1 mAh g-1 at 3400 mA g-1 ) and cycling stability (65.3% capacity retention after 1000 cycles at 170 mA g-1 ). Furthermore, the as-reported non-aqueous ball-milling method could be regarded as a promising method for the scalable production of PBAs as cathode materials for high-performance SIBs.

Binders for sodium-ion batteries: progress, challenges and strategies.

Binders as a bridge in electrodes can bring various components together thus guaranteeing the integrity of electrodes and electronic contact during battery cycling. In this review, we summarize the recent progress of traditional binders and novel binders in the different electrodes of SIBs. The challenges faced by binders in terms of bond strength, wettability, thermal stability, conductivity, cost, and environment are also discussed in details. Correspondingly, the designing principle and advanced strategies of future research on SIB binders are also provided. Moreover, a general conclusion and perspective on the development of binder design for SIBs in the future are presented.

Soft-Carbon-Coated, Free-Standing, Low-Defect, Hard-Carbon Anode To Achieve a 94% Initial Coulombic Efficiency for Sodium-Ion Batteries.

Developing hard carbon with a high initial Coulombic efficiency (ICE) and very good cycling stability is of great importance for practical sodium-ion batteries (SIBs). Defects and oxygen-containing groups grown along either the carbon edges or the layers, however, are inevitable in hard carbon and can cause a tremendous density of irreversible Na+ sites, decreasing the efficiency and therefore causing failure of the battery. Thus, eliminating these unexpected defect structures is significant for enhancing the battery performance. Herein, we develop a strategy of applying a soft-carbon coating onto free-standing hard-carbon electrodes, which greatly hinders the formation of defects and oxygen-containing groups on hard carbon. The electrochemical results show that the soft-carbon-coated, free-standing hard-carbon electrodes can achieve an ultrahigh ICE of 94.1% and long cycling performance (99% capacity retention after 100 cycles at a current density of 20 mA g-1), demonstrating their great potential in practical sodium storage systems. The sodium storage mechanism was also investigated by operando Raman spectroscopy. Our sodium storage mechanism extends the "adsorption-intercalation-pore filling-deposition" model. We propose that the pore filling in the plateau area might be divided into two parts: (1) sodium could fill in the pores near the inner wall of the carbon layer; (2) when the sodium in the inner wall pores is close to saturation, the sodium could be further deposited onto the existing sodium.

[Preliminary study on human bone marrow mesenchymal stem cells differentiation into epithelial-like cells].

OBJECTIVE: To investigate the differentiation potential of human bone marrow mesenchymal stem cells (hMSC) inducing into epithelial-like cells, even corneal epithelial-like cells, and to discuss the plasticity that make hMSC the seed cells used in corneal tissue engineering. METHODS: hMSC were isolated and purified by density gradient centrifugation combined with an attachment culture method and passaged in vitro. hMSC were identified by flow cytometry. The passaged hMSC were planted on fresh pig corneal Bowman's membrane. The expression of CK12, ABCG2 and CK19 in hMSC was identified by immunofluorescence staining. We used in vitro method to obtain a multilayer culture of hMSC. When hMSC formed a monolayer, the cells were inserted to Millicell culture and grew into multilayers by using the air-lifting cultivation methodology. Four weeks later, after fixed and dehydrated, the hMSC were observed under the light microscope after hemotoxylin and eosin (HE) and immunohistochemistry staining. RESULTS: hMSC could be cultured, expanded in vitro, and showed great potential of proliferation. The result of flow cytometry showed that the positive staining percentage was 0.06% for CD45, 0.41% for CD34, 86.43% for CD44, 85.72% for CD29 and 90.72% for CD105. This indicated that hMSC expressed CD44, CD29, CD105 but not CD45 and CD34. After four weeks induction, part of hMSC expressed CK12 and CK19 but not ABCG2. In the in vitro stratification, HE and immunohistochemical staining showed that there were one or two layers epithelial-like cells, even corneal epithelial-like cells after using the air-lifting cultivation. CONCLUSIONS: This study suggests that hMSC have the potential to differentiate into epithelial cells, even corneal epithelial cells. hMSC could be the option of cells used to reconstruct the corneal epithelium by tissue engineering technology.