An effective strategy for dendrite free Li metal anodes:Nickel foam decorated with high lattice-matching CoN and CoF_(2) nanosheets for dense deposition

The notorious dendrite and infinite volume change seriously restrict the advancement of lithium metal anodes(LMAs),during the long-term process of stripping/plating.Herein,the nanosheets of metal fluoride(CoF_(2))and metal nitride(CoN)with magnificent lithiophilicity on the nickel(Ni)foam are designed as the“regulator”to uniform the Li plating and build stronger solid electrolyte interface(SEI)layer for dendrite free LMAs.The Ni foam offers abundant space to receive deposited Li metal.The CoN nanosheets can guarantee the fast transfer of electrons,which provides a stable interface of Li^(+)reduction.Moreover,the nanosheet structure with lithiophilicity would accelerate the move of Li+and decrease the nucleation barrier,due to the high lattice-matching of Li and CoN.Meanwhile,the CoF_(2) could increase the content of F(LiF)in the SEI layer,which enhances the strength and avoids the destruction of SEI layer.With the cooperation of CoN and CoF_(2),the composited anode(Li/NF@CNCF)exhibits ultra-long cycle performance(more than 1200 h)and fantastic structure stability at 1 mA·cm^(-2) with 1 mAh·cm^(-2).Based on the LiFePO_(4) and Li/NF@CNCF,the full cells deliver excellent specifical capacity and steady coulombic efficiency.The strategy contributes an effective approach to alleviate the issues of lithium metal anodes in the field of LMAs.

Tunable oxygen vacancy concentration in vanadium oxide as mass-produced cathode for aqueous zinc-ion batteries

Oxygen vacancy(Vö)is important in the modification of electrode for rechargeable batteries.However,due to the scarcity of suitable preparation strategy with controllable Vöincorporation,the impact of Vöconcentration on the electrochemical performances remains unclear.Thus,in this work,Vö-V_(2)O_(5)-PEDOT(VöVP)with tunable Vöconcentration is achieved via a spontaneous polymerization strategy,with the capability of mass-production.The introduction of poly(2,3-dihydrothieno-1,4-dioxin)(PEDOT)not only leads to the formation of Vöin V_(2)O_(5),but it also results in a larger interlayer spacing.The as-prepared Vö-V_(2)O_(5)-PEDOT-20.3%with Vöconcentration of 20.3%(denoted as VöVP-20)is able to exhibit high capacity of 449 mAh·g^(−1) at current density of 0.2 A·g^(−1),with excellent cyclic performance of 94.3% after 6,000 cycles.It is shown in the theoretical calculations that excessive Vöin V_(2)O_(5) will lead to an increase in the band gap,which inhibits the electrochemical kinetics and charge conductivity.This is further demonstrated in the experimental results as the electrochemical performance starts to decline when Vöconcentration increases beyond 20.3%.Thus,based on this work,scalable fabrication of high-performance electrode with tunable Vöconcentration can be achieved with the proposed strategy.

Direct synthesis of tin spheres/nitrogen-doped porous carbon composite by self-formed template method for enhanced lithium storage

To inhibit the agglomeration of tin-based nanomaterials and simplify the complicated synthesis process,a facile and eco-friendly self-formed template method is reported to synthesize tin submicron spheres dispersed in nitrogen-doped porous carbon(Sn/NPC)by pyrolysis of a mixture of disodium stannous citrate and urea.The vital point of this strategy is the formation of Na_(2)CO_(3)templates during pyrolysis.This self-formed Na_(2)CO_(3)acts as porous templates to support the formation of NPC.The obtained NPC provides good electronic conductivity,ample defects,and more active sites.Serving as anode for Li-ion batteries,the Sn/NPC electrode obtains a stable discharge capacity of 674.1 mAh/g after 150 cycles at 0.1 A/g.Especially,a high discharge capacity of 331.2 mAh/g can be achieved after 1100 cycles at 3 A/g.Additionally,a full cell coupled with LiCoO_(2)as cathode yields a discharge capacity of 524.8 mAh/g after 150 cycles at 0.1 A/g.In-situ XRD is implemented to investigate the alloying/dealloying reaction mechanisms.Density functional theory calculation ulteriorly explicates that NPC heightens intrinsic electronic conductivity,and NPC especially pyrrolic-N and pyridinic-N doping facilitates the Li-adsorption ability.Climbing image nudged elastic band method reveals low Li~+diffusion energy barrier in presence of N atoms,which accounts for the terrific electrochemical properties of Sn/NPC electrode.