Aqueous Zn-MnO_(2) battery: Approaching the energy storage limit with deep Zn^(2+) pre-intercalation and revealing the ions insertion/extraction mechanisms

Rechargeable aqueous zinc ion batteries(AZIBs)were considered as one of the most promising candidates for large-scale energy storage due to the merits of high safety and inexpensiveness.As AZIBs cathode material,Mn O_(2)possesses great merits but was greatly hindered due to the sluggish diffusion kinetic of Zn^(2+) during electrochemical operations.Herein,deep Zn^(2+) ions intercalatedδ-Mn O_(2)(Zn-Mn O_(2))was achieved by the in situ electrochemical deposition route,which significantly enhanced the diffusion ability of Zn^(2+) due to the synergistic effects of Zn^(2+) pillars and structural H;O.The resultant Zn-Mn O_(2)based AZIBs delivers a record capacity of 696 m Ah/g(0.5 m Ah/cm^(2))based on the initial mass loading,which is approaching the theoretical capacity of Mn O_(2)with a two-electrons reaction.In-situ Raman studies reveal highly reversible Zn^(2+)ions insertion/extraction behaviors and here the Zn-Mn O_(2)plays the role of a container during the charge–discharge process.Further charge storage mechanism investigations point out the insertion/extraction of Zn^(2+) and H^(+) coincides,and such process is significantly facilitated results from superior interlayered configurations of Zn-Mn O_(2)The excellent electrochemical performance of Zn-Mn O_(2)achieved in this work suggests the deep ions pre-intercalation strategy may aid in the future development of advanced cathodes for AZIBs.

High-performance magnesium ion asymmetric Ppy@FeOOH//Mn3O4 micro-supercapacitor

Micro-supercapacitors(MSCs)are attractive electrochemical energy storage devices owing to their high power density and extended cycling stability.However,relatively low areal energy density still hinders their practical applications.Here,an asymmetric Mg ion MSC with promising high energy density is fabricated.Firstly,indium tin oxide(ITO)NWs were synthesized by chemical vapor deposition as the excellent current collector.Subsequently,nanostructured Mn_(3)O_(4)and Ppy@FeOOH were deposited on the laser-engraved interdigital structure ITO NWs electrodes as the positive and negative electrodes,respectively.Beneficial from the hierarchical micro-nano structures of active materials,high conductive electron transport pathways,and charge-balanced asymmetric electrodes,the obtained MSC possesses a high potential window of 2.2 V and a high areal capacitance of 107.3 mF cm^(-2)at 0.2 mA cm^(-2).The insitu XRD,VSM,and ex-situ XPS results reveal that the primary energy storage mechanism of Mg ions in negative FeOOH electrode is Mg ions de-/intercalation and phase transition reaction of FeOOH.Furthermore,the MSC exhibits a high specific energy density of 71.18μWh cm^(-2)at a power density of 0.22 mWh cm^(-2)and capacitance retention of 85%after 5000 cycles with unvaried Coulombic efficiency.These results suggest promising applications of our MSC in miniaturized energy storage devices.

The thermodynamically directed dendrite-free lithium metal batteries on LiZn alloy surface

Metical lithium(Li)is one of the most promising alternatives as an anode in next-generation high energy batteries for its high theoretical specific capacity and low redox potential.However,severe Li dendrite growth leading to poor stability and safety issues hinders its practical implementation.Herein,three-dimensional carbon cloth(CC)with full zinc oxide quantum dots(ZnO QDs)covering is rationally chosen as the substrate for the suppression of Li dendrite.Owing to the spontaneous reaction between ZnO QDs and molten Li,LiZn alloy is formed and covered on CC,which endows substrate with high affinity for Li adsorption and suitable barrier energy for Li diffusion.This thermodynamic regulation on substrate is beneficial for homogeneous Li nucleation and deposition,thus enabling high stability for over 1,900 h at ultrahigh current density of 10 mA∙cm^(−2) in symmetrical cell and delivering superior performance in full batteries.