Electrodeposition of a dendrite-free 3D Al anode for improving cycling of an aluminum-graphite battery

Aluminum-metal batteries show great potential as next-generation energy storage due to their abundant resources and intrinsic safety.However,the crucial limitations of metallic Al anodes,such as dendrite and corrosion problems in conventional aluminum-metal batteries,remain challenging and elusive.Here,we report a novel electrodeposition strategy to prepare an optimized 3D Al anode on carbon cloth with an uniform deposition morphology,low local current density,and mitigatory volume change.The symmetrical cells with the 3D Al anode show superior stable cycling(>450 h)and low-voltage hysteresis(~170 mV)at 0.5 mA cm^(−2).High reversibility(~99.7%)is achieved for the Al plating/stripping.The graphite||Al‐4/CC full batteries show a long lifespan of 800 cycles with 54 mAh g^(−1) capacity at a high current density of 1000 mA g^(−1),benefiting from the high capacitive-controlled distribution.This study proposes a novel strategy to design 3D Al anodes for metallic-Al-based batteries by eliminating the problems of planar Al anodes and realizing the potential applications of aluminum-graphite batteries.

Surficial modification enabling planar Al growth toward dendrite-free metal anodes for rechargeable aluminum batteries

Al metal possesses ultrahigh theoretical volumetric capacity of 8,040 m Ah cm^(-3),and gravimetric capacity of 2,980 m Ah g^(-1),and thus is highly attractive for electrochemical energy storage.However,it suffers from several issues,such as the dendrite formation,during Al stripping-deposition cycling,which has been verified to account for the short circuit and limited cyclic performance.Herein,we use a facile and applicable method to in-situ reconstruct the Al anode surface with F-Al-O chemical bonds,which could preferentially induce the planar growth of Al along the interface plane,thus leading to the dendrite-free morphology evolution during the cycling.Benefiting from F-Al-O chemical bonds on the surface of Al anodes,long lifespan of symmetric cells can be realized even under 1 m A cm^(-2)and 1 m Ah cm^(-2).Coupling the F-Al anode with graphite-based cathodes,high-voltage dual-ion Al metal batteries can be achieved with long-term cycle stability up to 1,200 cycles(at 0.5 m A cm^(-2)),surpassing the counterparts using pristine Al metal anode.Furthermore,the effectiveness of this surficial modification strategy is also elucidated with the aid of theoretical calculation.This work provides novel insights on low-cost and facile strategies against the Al dendrite growth in aluminum batteries.

Preparation of Hydroxyapatite-titanium Dioxide Coating on Ti6Al4V Substrates using Hydrothermal-electrochemical Method

Ti6Al4V substrates were anodized in a 0.5 mol/L H_2SO_4 solution at applied voltages of 90-140 V.A hydroxyapatite-titanium oxide（HA-TiO2）coating was then deposited on the anodized Ti6Al4 V substrates via a hydrothermal-electrochemicalmethod at a constant current.The obtained films and coatings were characterized by X-ray diffraction,scanning electron microscopy,energy-dispersive X-ray spectroscopy,and Fourier-transform infrared spectrometry.The microstructures of the porous films on the Ti6Al4 V substrates were studied to investigate the effect of the anodizing voltage on the phase and morphology of the HATiO_2 coating.The results indicated that both the phase composition and the morphology of the coatings were significantly influenced by changes in the anodizing voltage.HA-TiO_2 was directly precipitated onto the surface of the substrate when the applied voltage was between 110 and 140 V.The coatings had a gradient structure and the HA exhibited both needle-like and cotton-like structures.The amount of cotton-like HA structures decreased with an increase in voltage from 90 to 120 V,and then increased slightly when the voltage was higher than 120 V.The orientation index of the（002）plane of the coating was at a minimum when the Ti6Al4 V substrate was pretreated at 120 V.

Formation of Ultrafine Metal Particles and Metal Oxide Precursor on Anodized Al by Electrolysis Deposition

Nickel was deposited by ac electrolysis deposition in the pores of the porous oxide film of Al produced by anodizing in phosphoric acid. Ultrafine rod-shaped Ni particles were formed in the pores. At the same time a film of Ni oxide precursor was developed on the surface of the porous oxide film. The Ni particles and the Ni oxide precursor were examined by SEM, TEM and X-ray diffraction. The thickness of the barrier layer of the porous oxide film was thin and it attributed to the formation of the metal particles, while the formation of the oxide precursor was associated with the surface pits which were developed in the pretreatment of Al.