Revealing the effect of electrolyte coordination structures on the intercalation chemistry of batteries

In-depth understanding of the electrolyte-dependent intercalation chemistry in batteries through direct operando/in situ characterizations is crucial for the development of the high-performance batteries.Herein,taking the Al/graphite battery as a model system,the effect of electrolyte coordination structure on the intercalation processes has been investigated over the batteries with either 1-hexyl-3-methylimidazolium chloride(HMICl)-AlCl_(3) or 1-ethyl-3-methylimidazolium chloride(EMICl)-AlCl_(3) ionic liquid electrolyte using operando X-ray photoelectron spectroscopy(XPS)and X-ray diffraction.With a weaker anion-cation interaction in HMI-based electrolyte,the XPS-derived atomic ratio between cointercalated N and intercalated Al is 0.9,which is lower than 1.6 for EMI-based electrolyte.Attributed to the additional de-solvation process,the batteries with the HMI-based electrolyte show a lower ionic diffusion rate,capacity,and cycling performance,which agree with the operando characterization results.Our findings highlight the critical role of the electrolyte coordination structure on the(co-)intercalation chemistry.

Fast and extensive intercalation chemistry in Wadsley-Roth phase based high-capacity electrodes

Wadsley-Roth (W-R) structured oxides featured with wide channels represent one of the most promising material families showing compelling rate performance for lithium-ion batteries.Herein,we report an indepth study on the fast and extensive intercalation chemistry of phosphorus stabilized W-R phase PNb_(9)O_(25) and its application in high energy and fast-charging devices.We explore the intercalation geometry of PNb_(9)O_(25) and identify two geometrical types of stable insertion sites with the total amount much higher than conventional intercalation-type electrodes.We reveal the ion transportation kinetics that the Li ions initially diffuse along the open type Ⅲ channels and then penetrate to edge sites with low kinetic barriers.During the lithiation,no remarkable phase transition is detected with nearly intact host phosphorous niobium oxide backbone.Therefore,the oxide framework of PNb_(9)O_(25) keeps almost unchanged with all the fast diffusion channels and insertion cavities well-maintained upon cycling,which accomplishes the unconventional electrochemical performance of W-R structured electrodes.

Oxyvanite V3O5:A new intercalation-type anode for lithium-ion battery

In the present study,V3O5 microcrystals that synthesized via vacuum calcination are employed as anodes for lithium-ion batteries(LIBs)for the first time.Despite the widely observed sluggish reaction kinetics and poor cycling stability in most microsized transition metal oxides,the V3O5 microcrystals exhibit excellent rate capability(specific capacities of 144 and 125 mAh g^−1 are achieved at extremely high current densities of 20 and 50 A g^−1,respectively)and long-term cycling performance(specific capacity of 117 mAh g^−1 is sustained over 2000 cycles at 50 A g^−1).It is ascribed to the three-dimensional open-framework structure of the V3O5 microcrystals as a major factor in dictating the fast reaction kinetics(lithium diffusion coefficient:~10−9 cm^2 s^−1).In addition,significant insight into the reaction mechanism of the V3O5 microcrystals in concomitant its phase evolution are obtained from ex-situ XRD study,revealing that the V3O5 microcrystals undergo intercalation reaction with insignificant structural change in response to lithiation/delithiation.

Preparation,luminescence and photofunctional performances of a hybrid layered gadolinium-europium hydroxide

The design and fabrication of rare earth ions incorporated into the inorganic/organic hybrid materials have attracted growing attention for seeking improved optical properties and photofunctional performances.In this paper,a novel hybrid composite based on the layered rare earth hydroxides was successfully prepared by the ion-exchange and intercalation chemical process.The rare earth elements in the composite contain gadolinium(Gd)and europium(Eu)and the molar ratio of Gd to Eu is kept constant at 1.9:0.1.Organic sodium dodecyl sulfonate and dye coumarin-3-carboxyllc acid are simultaneously incorporated into the layered rare earth hydroxides as supporting agent and light-harvesting antenna,respectively.The resulting hybrid layered rare earth hydroxides exhibit the enlarged interlayer distance with about 2.60 nm,and the chemical composition was confirmed through X-ray diffraction,carbon,hydrogen and nitrogen(CHN)elemental analysis,infrared spectroscopy,and thermogravimetric analysis.The layered solid compound shows the characteristic red emission corresponding to the^(5)D_(0)→^(7)F_(2)transition of Eu^(3+)ion,and the luminescence intensity of the optimized compound is greatly enhanced as compared to its corresponding nitrate and the hybrid composite without the introduction of dye molecule.The hybrid layered rare earth hydroxides can be exfoliated into bright colloidal solution,which show superior recognition capability to Cu^(2+)ion with the distinct luminescence quenching.The large quenching constant(1.4×10^(4)L/mol)and low detection limit(0.35μmol/L)are achieved for Cu^(2+)ion,implying a"turn-off"fluorescent sensor for Cu^(2+)detection.Moreover,a transparent film was prepared based on the colloidal solution and displays the typical red emission in folded shape.The new hybrid compound with enhanced luminescence and excellent photofunctional performances is expected to be applied in the fields of fluorescent sensing and flexible optical devices.