Powder metallurgical 3D nickel current collectors with plasma-induced Ni3N nanocoatings enabling long-life and dendrite-free lithium metal anode

Building three-dimensional(3D) current collectors is a promising strategy to surmount the bottlenecks of lithium metal anodes(LMAs), but the regulation methodology of a 3D current collector has seldom been considered comprehensively concerning both skeleton architectures and surface coatings. Herein, a robust porous 3D nickel skeleton(NS) with lithiophilic NiN nanocoatings(NiN@NS) is synthesized via an integrative route of powder metallurgy/plasma-enhanced nitridation technics. The facile powder metallurgical method facilitates the adjustment of NS architectures toward sufficient electrolyte adsorption and even current density distribution, while the followed plasma-enhanced chemical vapor deposition(PECVD) method can induce compact NiN nanocoatings on NS, which reduces the Li nucleation overpotential, accelerates the Li-ion transfer, and facilitates a highly reversible oriented texture of Li deposition morphology owing to the dense and homogenous deposition of Li into the pores. The optimized NiN@NS current collector shows a high averaged Coulombic efficiency(CE) of 98.8% over 350cycles, a prolonged lifespan of 1000 h(at 2 mA cm^(-2)) in symmetrical cells, together with the significant performance in full cells. The ingenious methodology reported in this work can also be broadly applicable for the controllable production of other 3D skeletons with nitride nanocoatings for various applications.

Wire-Shaped 3D-Hybrid Supercapacitors as Substitutes for Batteries

We report a wire-shaped three-dimensional(3D)-hybrid supercapacitor with high volumetric capacitance and high energy density due to an interconnected 3D-configuration of the electrode allowing for large number of electrochemical active sites,easy access of electrolyte ions,and facile charge transport for flexible wearable applications.The interconnected and compact electrode delivers a high volumetric capacitance(gravimetric capacitance)of 73 F cm−3(2446 F g−1),excellent rate capability,and cycle stability.The 3D-nickel cobalt-layered double hydroxide onto 3D-nickel wire(NiCo LDH/3D-Ni)//the 3D-manganese oxide onto 3D-nickel wire(Mn3O4/3D-Ni)hybrid supercapacitor exhibits energy density of 153.3 Wh kg−1 and power density of 8810 W kg−1.The red lightemitting diode powered by the as-prepared hybrid supercapacitor can operate for 80 min after being charged for tens of seconds and exhibit excellent electrochemical stability under various deformation conditions.The results verify that such wire-shaped 3D-hybrid supercapacitors are promising alternatives for batteries with long charge–discharge times,for smart wearable and implantable devices.

Highly elastic wrinkled structures for stable and low volume-expansion lithium-metal anodes

Lithium(Li)metal is promising for high energy density batteries due to its low electrochemical redox potential and high specific capacity.However,the formation of dendrites and its tendency for large volume expansion during plating/stripping restrict the application of Li metal in practical scenarios.In this work,we developed reduced graphene oxide-graphitic carbon nitride(rGO-C3N4,GCN)with highly elastic and wrinkled structure as the current collector.Lithiophilic site C3N4 in GCN could reduce the nucleation overpotential.In addition,this material effectively inhibited electrode expansion during cycling.At the same time,due to its high elasticity,GCN could release the stress induced by Li deposition to maintain structural integrity of the electrode.Limetal anodes with GCN exhibited small volume expansion,high Coulombic efficiency(CE)of 98.6%within 300 cycles and long cycling life of more than 1700 h.This work described and demonstrated a new approach to construct flexible current collectors for stable lithium-metal anodes.