Homogenous metallic deposition regulated by abundant lithiophilic sites in nickel/cobalt oxides nanoneedle arrays for lithium metal batteries

Although lithium(Li)metal delivers the highest theoretical capacity as a battery anode,its high reactivity can generate Li dendrites and"dead"Li during cycling,resulting in poor reversibility and low Li utilization.Inducing uniform Li plating/stripping is the core of solving these problems.Herein,we design a highly lithiophilic carbon film with an outer sheath of the nanoneedle arrays to induce homogeneous Li plating/stripping.The excellent conductivity and 3D framework of the carbon film not only offer fast charge transport across the entire electrode but also mitigate the volume change of Li metal during cycling.The abundant lithiophilic sites ensure stable Li plating/stripping,thereby inhibiting the Li dendritic growth and"dead"Li formation.The resulting composite anode allows for stable Li stripping/plating under 0.5 mA cm^(-2) with a capacity of 0.5 mA h cm^(-2) for 4000 h and 3 mA cm^(-2) with a capacity of3 mA h cm^(-2) for 1000 h.The Ex-SEM analysis reveals that lithiophilic property is different at the bottom,top,or channel in the structu re,which can regulate a bottom-up uniform Li deposition behavior.Full cells paired with LFP show a stable capacity of 155 mA h g^(-1) under a current density of 0.5C.The pouch cell can keep powering light-emitting diode even under 180°bending,suggesting its good flexibility and great practical applications.

Unveiling the role of lithiophilic sites denseness in regulating lithium ion deposition

The construction of lithiophilic sites is an effective way to achieve uniform lithium(Li)ion deposition for stably cycling Li metal batteries.However,in-depth investigations involving lithiophilic sites denseness(LSD)in impacting Li ion deposition remain unknown.Herein we propose an insight into this issue by probing the effect of LSD on determining the Li ion deposition.Experimental characterization and theoretical simulation demonstrate that rational LSD plays a vital role in both Li nucleation and the subsequent Li ion plating behaviors.By tailoring the LSD from low to high,the accompanied Li nucleation overpotentials continuously decrease.Additionally,the Li ion mobility increases first and then weakens in the subsequent Li ion plating stage.Consequently,the Li metal with a moderate LSD allows a dendritefree morphology and satisfactory long-term cycling performances.This work affords a deeper fundamental understanding of lithiophilic chemistry that directs the development of efficient strategies to realize dendrite-free Li metal batteries.

Single-atomic Zn-(C/N/O)lithiophilic sites induced stable lithium plating/stripping in anode-free lithium metal battery

For anode-free lithium metal battery,lithiophilic surface modification on the current collector can effectively reduce the lithium nucleation barrier,so as to regulate the electrodeposition of lithium.Here,atomically dispersed Zn-(C/N/O)lithiophilic sites in the amorphous carbon medium were introduced onto Cu by an in-situ induced ion coordination chemistry strategy to get the modified Zn@NC@RGO@Cu current collector.X-ray absorption spectroscopy(XAS)combined with scanning transmission electron microscopy in high angle annular dark field(STEM-HAADF)analysis proved the single atomic state of the zinc sites surrounded by C,N,and O with a coordination number of~3.According to the electrochemical tests and first principle calculations,the ultra-uniformly dispersed Zn-(C/N/O)sites at the atomic level can effectively improve the lithium affinity,reduce the energy barrier for lithium nucleation,homogenize the lithium nucleation,and enhance an inorganic lithium compounds rich solid electrolyte interphase layer.As a result,the nucleation overpotential of lithium on the modified current collector was reduced to 7.7 mV,which was 5.4 times lower than that on bare Cu.Uniform lithium nucleation and deposition enabled stable Li plating/stripping and elevated Coulombic efficiency of 98.95%in Li||Cu cell after>850 cycles.Capacity retention of 89.7%was successfully achieved in the anode-free lithium metal battery after 100 cycles.

A 10-μm Ultrathin Lithium Metal Composite Anodes with Superior Electrochemical Kinetics and Cycling Stability

Lithium metal is a promising candidate for the promotion of the next generation high energy density batteries.The employment of ultrathin Li metal anode with controllable thickness could enable a higher efficiency of Li utilization.Herein,a simple method to fabricate free-standing 10μm ultrathin Li metal anode is developed in this work.A three-dimensional MnO_(x)-coated CNT framework is constructed through a facile hydrothermal process,utilizing as a host for molten Li infusion,which could not only put forward a simple strategy to modulate the thickness of Li metal film but also restricts the volume expansion.The abundant MnO_(x)nanoparticles acting as lithiophilic sites reduce the Li nucleation barrier and optimize the electrochemical kinetics at the anode/electrolyte interface.As a result,the ultrathin Li composite anode exhibits a superior lifespan expanded to 2000 cycles in a symmetric cell,as well as a better capacity and rate capability than that of bare Li anode in full cell,fulfilling the requirements of high energy density and stable cycling life.Furthermore,a wave-shaped Li metal pouch cell based on the ultrathin Li composite anode is assembled that exhibits remarkable mechanical bending toleration and cyclic stability,demonstrating large potential application in the field of flexible wearable devices.

Lithium deposition behavior in hard carbon hosts:Optical microscopy and scanning electron microscopy study

Lithium(Li)metal is an ideal anode for the next generation high-energy-density batteries.However,it suffers from dendrite growth,side reactions,and infinite relative volume change.Effective strategies are using porous carbons or surface modification carbons to guide Li deposition into their pores.While the Li deposition behavior is still ambiguous.Here,we systematically determine their deposition behavior in various surface-modified carbons and in different electrolytes via optical microscopy and scanning electron microscopy study.It is found that Li will not spontaneously deposit into the carbon pores,which is significantly dependent on the carbon surface,current density,areal capacity,and electrolyte.Thus,a“lithiophilic”modified commercial hard carbon with Ag is developed as a stable“host”and efficient surface protection derived from the localized high-concentration electrolyte exhibits a pretty low volume change(5.3%)during cycling at a current density of 2 mA·cm^(−2)and an areal capacity of 2 mAh·cm^(−2).This strategy addresses the volume change and dendrite problems by rationally designed host and electrolyte,providing a broad perspective for realizing Li-metal anode.

Regulating lithium affinity of hosts for reversible lithium metal batteries

Lithium(Li)metal batteries are regarded as the“holy grail”of nextgeneration rechargeable batteries,but the poor redox reversibility of Li anode hinders its practical applications.While extensive studies have been carried out to design lithiophilic substrates for facile Li plating,their effects on Li stripping are often neglected.In this study,by homogeneously loading indium(In)single atoms on N-doped graphene via In-N bonds,the affinity between Li and hosting substrates is regulated.In situ observation of Li deposition/stripping processes shows that compared with the N-doped graphene substrate,the introduction of In effectively promotes its reversibility of Li redox,achieving a dendrite-free Li anode with muchimproved coulombic efficiency.Interestingly,theoretical calculations demonstrate that In atoms have actually made the substrate less lithophilic via passivating the N sites to avoid the formation of irreversible Li-N bonding.Therefore,a“volcano curve”for reversible Li redox processes is proposed:the affinity of substrates toward Li should be optimized to a moderate value,where the balance for both Li plating and Li stripping processes could be reached.By demonstrating a crucial design principle for Li metal hosting substrates,our finding could trigger the rapid development of related research.