Metal-organic cage as fluorescent probe for LiPF_(6)in lithium batteries

Lithium hexafluorophosphate(LiPF_(6)),the most commonly used lithium battery electrolyte salt,is vulnerable to heat and humidity.Quantitative and qualitative determination the variation of LiPF_(6)have always relied on advanced equipment.Herein,we develop a fast,convenient,high-selective fluorescence detection method based on metal-organic cages(MOC),whose emission is enhanced by nearly 20 times in the presence of LiPF_(6)with good stability and photobleaching resistance.The fluorescent probe can also detect moisture in battery electrolyte.We propose and verify that the luminescence enhancement is due to the presence of hydrogen bond-induced enhanced emission effect in cages.Fluorescent excitation-emission matrix spectra and variable-temperature nuclear magnetic resonance spectroscopy are employed to clarify the role of hydrogen bonds in guest-loaded cages.Density functional theory(DFT)calculation is applied to simulate the structure of host-guest complexes and estimate the adsorption energy involved in the system.The precisely matched lock-and-key model paves a new way for designing and fabricating novel host structures,enabling specific recognition of other target compounds.

Depolarization of Li-rich Mn-based oxide via electrochemically active Prussian blue interface providing superior rate capability

The high-rate cyclability of Li-rich Mn-based oxide(LMO)is highly limited by the electrochemical polarization resulting from the slow kinetic of the Li2MnO3 phase.Herein,the Prussian blue(PB)coating layer with specific redox potential is introduced as a functionalized interface to overcome the side effect and the escaping of O on the surface of LMO,especially its poor rate capability.In detail,the PB layer can restrict the large polarization of LMO by sharing overloaded current at a high rate due to the synchronous redox of PB and LMO.Consequently,an enhanced high rate performance with capacity retention of 87.8%over 300 cycles is obtained,which is superior to 50.5%of the pristine electrode.Such strategies on the high-rate cyclability of Li-rich Mn-based oxide compatible with good low-rate performances may attract great attention for pursuing durable performances.

Casting structure of pure aluminum by electric pulse modification at different superheated temperatures

Electric pulse modification （EPM） is a novel technique that reduces grain size by altering the structure of a melt. It was investigated that the response of the casting structure of high pure aluminum to EPM in different superheated melts. The results indicate that the grain refining effect of a given pulse electric field holds an optimal temperature range, moreover, a lower or higher superheated temperature will both disadvantage the improvements of casting structure. It essentially lies in the cooperative action between the distorted absorption of clusters and the activated capability of atoms in the aluminum melt.

Skin care design for lithium metal protection with cosmetics introduction

Lithium metal anode(LMA)is the ultimate"Holy Grail"electrode for next generation high-energy-density batteries.Nevertheless,its instinct high reactivity is a formidable challenge and has intensified side reactions,destabilized the electrode/electrolyte interface and restricted the operating conditions strictly,thus hampering its practical application.Here,we"make up"the Li metal(M-Li)by constructing vaselinecoated layer by a simple dip-coating or casting method.With the chemically stable and hydrophobic vaseline protective layer,the stability of Li towards humid and corrosive atmosphere has been greatly improved.The M-Li guaranteed stable and prolonged cycling life after the anode suffering from corrosion in moist air(relative humidity-65%)or corrosive electrolyte(with 10,000 ppm H2O or S)both in symmetric cells and LiFePO4 full cells.This work illustrates a convenient,economic,and industrial applicable method for stable LMA.

Processable Potassium Metal Anode for Stable Batteries

The future of high-energy density electrochemical energy storage systems relies on the advancement of rechargeable batteries that utilize reactive metals as anodes.In the alkaline metal,secondary battery systems because of abundant resource,high capacity and low redox potential,potassium(K)metal secondary battery(KMB)is expected to replace the existing lithiumion battery as a versatile platform for high-energy density,cost-effective energy storage devices.However,the difficulty in processing metal K results in nonstandard electrodes and hinders the development of KMBs.Furthermore,the mobility of the K metal anode due to its unique lowmelting point character at elevated temperatures in practical conditions leads to severe instability and risks in chemical/electrochemical processes.Herein,we fabricate a processable and moldable composite K metal anode by encapsulating K into reduced graphene oxide(rGO).The composite electrode can be engineered into various shapes discretionarily with precise sizes and stabilize the K metal anode at relatively high temperatures.Remarkably,the composite anode exhibits excellent cycling performance at high current density(8 mA cm^(-2)) with dendrite-free morphology.Paired with a Prussian blue cathode,the rGO-K composite anode shows much improved electrochemical performance and extended lifetime.

Revealing the solid electrolyte interface on calcium metal anodes

Owing to its low potential, crustal abundances and environmental friendliness, calcium metal anode(CMA) is emerging as a powerful contender in post-lithium era. However, the passivation of CMA fatally hinders its development. Recently, several feasible electrolytes have been developed. Nevertheless, as a pivotal part, the solid electrolyte interface(SEI) formed on CMA has not been paid enough attention to. In this review, based on the passivation mechanism of CMA, the favorable composition of SEI is emphasized with the corresponding electrolytes. It is considered that boron-containing and organic–inorganic hybrid SEI might be preferred. By comparing electrolytes and SEI on CMA with lithium and magnesium metal anodes, the root causes of CMA passivation are further elaborated, enlightening rational design rules of suitable SEI. Furthermore, some noteworthy details when assembling secondary calcium metal batteries(CMBs) are put forward. It is expected that deeper understanding of SEI on CMA will promote the development of CMBs.

Disulfide Crosslinking-Induced Aggregation:Towards Solid-State Fluorescent Carbon Dots with Vastly Different Emission Colors

Solid-state fluorescent multi-color carbon dots(SFM-CDs),prepared using the same precursor(s)without the need for dispersion in a solid matrix,are highly demanded for a wide range of applications.Herein,we report a microwave-assisted strategy for the prepara-tion of SFM-CDs with blue,yellow and red emissions within 5 min from the same precursors.The as-prepared B-CDs,Y-CDs,and R-CDs possessed bright fluorescence at 425 nm,550 nm,and 640 nm,and photoluminescence quantum yields(PLQYs)of 54.68%,17.93%,and 2.88%,respectively.The structure of SFM-CDs consisted of 5-oxo-3,5-dihydro-2H-thiazolo[3,2-a]pyridine-7-carboxylic acid(TPCA)immobilized on the surface of a carbon core,with the size of the carbon core and degree of disulfide crosslinking between CDs both increasing on going from the B-CDs to the R-CDs,as verified by mechanochromic experiments.The excellent solid-state fluorescence performance of the SFM-CDs allowed their utilization as the fluorescent converter layer in multi-color LEDs and white LEDs with a high color rendering index.

Recent advances in solid polymer electrolytes for lithium batteries

Solid polymer electrolytes are light-weight, flexible, and non-flammable and provide a feasible solution to the safety issues facing lithium-ion batteries through the replacement of organic liquid electrolytes. Substantial research efforts have been devoted to achieving the next generation of solid-state polymer lithium batteries. Herein, we provide a review of the development of solid polymer electrolytes and provide comprehensive insights into emerging developments. In particular, we discuss the different molecular structures of the solid polymer matrices, including polyether, polyester, polyacrylonitrile, and polysiloxane, and their interfacial compatibility with lithium, as well as the factors that govern the properties of the polymer electrolytes. The discussion aims to give perspective to allow the strategic design of state-of-the-art solid polymer electrolytes, and we hope it will provide clear guidance for the exploration of high-performance lithium batteries.

Dendrite-free all-solid-state lithium batteries with lithium phosphorous oxynitride-modified lithium metal anode and composite solid electrolytes

Dendrite formation on lithium (Li) metal anode is a key issue which hinders the development of rechargeable Li battery seriously. A novel method for suppress!ng Li dendrites via using Li phosphorous oxynitride (UPON) modified Li anode and Li1.5Al0.5Ge1.5(PO4)3-poly(ethylene oxide)(Li bistrifluoromethane-sulfonimide)(LAGP-PEO(LiTFSI)) composite solid electrolyte in all-solid-state Li battery is proposed, and the effect of the thickness of UPON on Li anode performarice is also studied. LiPON film with a thickness of 500 nm exhibits satisfactory interface property between Li metal anode and the LAGP-PEO(LiTFSI) solid electrolyte. The LiPON film provides a uniform Li^+ flux across the interface and effectively inhibits the formation of Li dendrites in all-solid-state Li batteries. The assembled all-solid-state Li cell Li(LiPON)/LAGP-PEO(LiTFSI)/LiFePO4 delivers an initial discharge capacity of 152.4 mAh·g^-1 and exhibits good cycling stability and rate performanee at 50 ℃.

A novel monoclinic manganite/multi-walled carbon nanotubes composite as a cathode material of lithium-air batteries

A novel composite of monoclinic manganite/multi-walled carbon nanotubes(c-MnOOH/MWCNTs)composite as a cathode material of lithium-air batteries was successfully synthesized by a simple one-step hydrothermal method.Owing to the unique three-dimensional network of c-MnOOH embedded in the porous structure of MWCNTs,the c-MnOOH/MWCNTs composite could have an advantage of high electrocatalytic activities over those of two other kinds of cathode materials(MWCNTs and c-MnOOH/MWCNTs mixture).The results of chargedischarge tests showed that the c-MnOOH/MWCNTs composite as a cathode material of lithium-air batteries could effectively enhance the catalytic activity for the oxygen evolution reduction(OER)process.The lithium-air battery based on c-MnOOH/MWCNTs composite exhibits low charge potential and high discharge capacity.

Advanced Electrode Materials in Lithium Batteries:Retrospect and Prospect

Lithium-(Li-)ion batteries have revolutionized our daily life towards wireless and clean style,and the demand for batteries with higher energy density and better safety is highly required.The next-generation batteries with innovatory chemistry,material,and engineering breakthroughs are in strong pursuit currently.Herein,the key historical developments of practical electrode materials in Li-ion batteries are summarized as the cornerstone for the innovation of next-generation batteries.In addition,the emerging electrode materials for next-generation batteries are discussed as the revolving challenges and potential strategies.Finally,the future scenario of high-energy-density rechargeable batteries is presented.The combination of theory and experiment under multiscale is highlighted to promote the development of emerging electrode materials.

A red-emitting water-soluble fluorescent probe for biothiol detection with a large Stokes shift

In this work, we presented a fluorescent probe(MCQ-DNBS) for selective and sensitive detection of biothiols based on a methylated chromenoquinoline(MCQ) derivative. Probe MCQ-DNBS was constructed by masking the OH group in MCQ with a common sensing unit, 2,4-dinitrobezensulfonate group(DNBS) for biothiols. Due to the photo-induced electron transfer(PET) process between MCQ and DNBS, this probe was weekly fluorescent. Upon the addition of biothiols(Cys, Hcy and GSH), this probe emitted a strong red fluorescence(λ_(em max)=613 nm) with a large Stokes shift(115 nm). In addition,fluorescence imaging of biothiols in living cells was successfully realized using MCQ-DNBS as a detector.

Anti-corrosive, weatherproof and self-healing polyurethane developed from hydrogenated hydroxyl-terminated polybutadiene toward surface-protective applications

Self-healing polyurethane(PU)faces aging deterioration due to active dynamic bonds,which remain a challenging predicament for practical use.In this work,a novel strategy is developed to address this predicament by leveraging the hydrophobicity and gas barrier of hydrogenated hydroxyl-terminated polybutadiene(HHPB).The dynamic oxime-carbamate bonds derived from 2,4-pentanedione dioxime(PDO)enable the elastomer to exhibit surface self-repairability upon applied mild heat and achieve~99.5%mechanical self-healing efficiency.The mechanical properties remained nearly intact after 30-d exposure to thermal oxidation,xenon lamp,acids,bases,and salts.Gas permeability,positron annihilation lifetime spectroscopy(PALS),and contact angle measurements reveal the pivotal role of gas barrier,free volume,and hydrophobicity in blocking undesirable molecules and ions which effectively protects the elastomer from deterioration.HHPB-PU also exhibits excellent adhesion to steel substrate.The shear strength achieves(3.02±0.42)MPa after heating at 80°C for 4 h,and(3.06±0.2)MPa after heating at 130°C for 0.5 h.Regarding its outstanding anti-corrosive and weatherproof performances,this self-healable elastomer is a promising candidate in surface-protective applications.