Layered Birnessite Cathode with a Displacement/Intercalation Mechanism for High-Performance Aqueous Zinc-Ion Batteries

Mn-based rechargeable aqueous zinc-ion batteries(ZIBs)are highly promising because of their high operating voltages,attractive energy densities,and eco-friendliness.However,the electrochemical performances of Mn-based cathodes usually suffer from their serious structure transformation upon charge/discharge cycling.Herein,we report a layered sodium-ion/crystal water co-intercalated Birnessite cathode with the formula of Na0.55Mn2O4·0.57H2O(NMOH)for high-performance aqueous ZIBs.A displacement/intercalation electrochemical mechanism was confirmed in the Mn-based cathode for the first time.Na+and crystal water enlarge the interlayer distance to enhance the insertion of Zn^2+,and some sodium ions are replaced with Zn^2+ in the first cycle to further stabilize the layered structure for subsequent reversible Zn^2+/H^+ insertion/extraction,resulting in exceptional specific capacities and satisfactory structural stabilities.Additionally,a pseudo-capacitance derived from the surface-adsorbed Na^+ also contributes to the electrochemical performances.The NMOH cathode not only delivers high reversible capacities of 389.8 and 87.1 mA h g^−1 at current densities of 200 and 1500 mA g^−1,respectively,but also maintains a good long-cycling performance of 201.6 mA h g^−1 at a high current density of 500 mA g^−1 after 400 cycles,which makes the NMOH cathode competitive for practical applications.

Synthesis,Crystal Structure and Photoluminescent Property of a Novel Dy^(3+) Coordination Compound Containing Rare(H_2O)_(22) Clusters

A novel Dy^（3＋） coordination compound,（H_2pipz）（H_3O）[Dy（pydc）_3]·11H_2O（1,pipz = piperazine and H_2pydc = pyridine-2,6-dicarboxylic acid）,has been hydrothermally synthesized and characterized by X-ray single-crystal diffraction,elemental analysis. It is interesting that the packing structure of compound 1 contains 22-core water clusters. Compound 1 is extended into a threedimensional supramolecular structure via O···H···O hydrogen bonding interactions. Furthermore,the luminescent property of compound 1 was also investigated.

Regulating dissolution chemistry of nitrates in carbonate electrolyte for high-stable lithium metal batteries

Lithium metal batteries(LMBs)have received increasing attention due to the high energy density.However,the practical application of LMBs is limited due to the incompatibility of ester electrolytes.Transition metal(TM)nitrates have been reported as effective additives in ester electrolyte to improve the stability of lithium anode.Unfortunately,the nitrates are restricted to use due to their poor solubility.We find that the nitrates containing crystal water have high solubility in ester electrolytes.Considering that most TM nitrates contain crystal water and the crystal water can be used as a perfect solubilizer of nitrates,thus,the method is of universality and facile without introducing any solubilizing agent.Herein,In(NO_(3))_(3.6)H_(2)O is chosen as one typical case with increased solubility up to 0.2 M compared with In(NO_(3))_(3)which hardly dissolves in ester electrolyte.The additive promotes the rapid and stable formation of the solid electrolyte interface(SEI),which effectively inhibits the lithium dendrites formation.Moreover,the induced cathode electrolyte interface(CEI)maintains the structural stability of Li Ni_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811).As a result,the electrochemical performance of Li|NCM811 cell is obviously improved.Our study provides a new idea for dissolving nitrates in ester electrolytes and discloses the synergistic function of TM-ions.

Eliminating crystal water enables enhanced sodium storage performance in an oxalate-phosphate cathode material

The oxalate-phosphate polyanion-mixed cathode materials are promising for sodium-ion batteries(SIBs)due to their unique open-framework structures and high voltage property.However,materials of this type generally contain crystal water molecules in the lattice frameworks,which may affect their energy storage properties.This work aims to disclose the impacts of crystal water on physiochemical and electrochemical properties of Na_(2)(VO)_(2)(HPO_(4))_(2)(C_(2)O_(4))·2H_(2)O(NVPC-W).It shows that the water molecules can be eliminated by vacuum drying at 150°C.The elimination of water molecules does not change the crystal phase of the material,while the obtained Na_(2)(VO)_(2)(HPO_(4))_(2)(C_(2)O^(4))(NVPC)exhibits significant improvements in cycling stability,Coulombic efficiency,as well as rate performances.Kinetics analysis indicates that the existence of lattice water molecules hinders sodium-ion diffusion and promotes the degradation of electrodes.We believe the findings can help to develop high-performance cathode materials.

Deposition behavior of residual aluminum in drinking water distribution system：Effect of aluminum speciation

Finished drinking water usually contains some residual aluminum.The deposition of residual aluminum in distribution systems and potential release back to the drinking water could significantly influence the water quality at consumer taps.A preliminary analysis of aluminum content in cast iron pipe corrosion scales and loose deposits demonstrated that aluminum deposition on distribution pipe surfaces could be excessive for water treated by aluminum coagulants including polyaluminum chloride（PACl）.In this work,the deposition features of different aluminum species in PACl were investigated by simulated coil-pipe test,batch reactor test and quartz crystal microbalance with dissipation monitoring.The deposition amount of non-polymeric aluminum species was the least,and its deposition layer was soft and hydrated,which indicated the possible formation of amorphous Al（OH）3.Al（13） had the highest deposition tendency,and the deposition layer was rigid and much less hydrated,which indicated that the deposited aluminum might possess regular structure and self-aggregation of Al（13）could be the main deposition mechanism.While for Al（30）,its deposition was relatively slower and deposited aluminum amount was relatively less compared with Al（13）.However,the total deposited mass of Al（30） was much higher than that of Al（13）,which was attributed to the deposition of particulate aluminum matters with much higher hydration state.Compared with stationary condition,stirring could significantly enhance the deposition process,while the effect of pH on deposition was relatively weak in the near neutral range of 6.7 to 8.7.