A 3D Lithiophilic Mo2N‐Modified Carbon Nanofiber Architecture for Dendrite‐Free Lithium‐Metal Anodes in a Full Cell

The pursuit for high‐energy‐density batteries has inspired the resurgence of metallic lithium (Li) as a promising anode, yet its practical viability is restricted by the uncontrollable Li dendrite growth and huge volume changes during repeated cycling. Herein, a new 3D framework configured with Mo₂N‐mofidied carbon nanofiber (CNF) architecture is established as a Li host via a facile fabrication method. The lithiophilic Mo₂N acts as a homogeneously pre‐planted seed with ultralow Li nucleation overpotential, thus spatially guiding a uniform Li nucleation and deposition in the matrix. The conductive CNF skeleton effectively homogenizes the current distribution and Li‐ion flux, further suppressing Li‐dendrite formation. As a result, the 3D hybrid Mo₂N@CNF structure facilitates a dendrite‐free morphology with greatly alleviated volume expansion, delivering a significantly improved Coulombic efficiency of ≈99.2% over 150 cycles at 4 mA cm^?2. Symmetric cells with Mo₂N@CNF substrates stably operate over 1500 h at 6 mA cm^?2 for 6 mA h cm^?2. Furthermore, full cells paired with LiNi_0.8Co_0.1Mn_0.1O₂ (NMC811) cathodes in conventional carbonate electrolytes achieve a remarkable capacity retention of 90% over 150 cycles. This work sheds new light on the facile design of 3D lithiophilic hosts for dendrite‐free lithium‐metal anodes.     

Dual‐Layered Film Protected Lithium Metal Anode to Enable Dendrite‐Free Lithium Deposition

Lithium metal batteries (such as lithium–sulfur, lithium–air, solid state batteries with lithium metal anode) are highly considered as promising candidates for next‐generation energy storage systems. However, the unstable interfaces between lithium anode and electrolyte definitely induce the undesired and uncontrollable growth of lithium dendrites, which results in the short‐circuit and thermal runaway of the rechargeable batteries. Herein, a dual‐layered film is built on a Li metal anode by the immersion of lithium plates into the fluoroethylene carbonate solvent. The ionic conductive film exhibits a compact dual‐layered feature with organic components (ROCO₂Li and ROLi) on the top and abundant inorganic components (Li₂CO₃ and LiF) in the bottom. The dual‐layered interface can protect the Li metal anode from the corrosion of electrolytes and regulate the uniform deposition of Li to achieve a dendrite‐free Li metal anode. This work demonstrates the concept of rational construction of dual‐layered structured interfaces for safe rechargeable batteries through facile surface modification of Li metal anodes. This not only is critically helpful to comprehensively understand the functional mechanism of fluoroethylene carbonate but also affords a facile and efficient method to protect Li metal anodes.     

Uniform Lithium Nucleation/Growth Induced by Lightweight Nitrogen‐Doped Graphitic Carbon Foams for High‐Performance Lithium Metal Anodes

The lithium metal anode has attracted soaring attention as an ideal battery anode. Unfortunately, nonuniform Li nucleation results in uncontrollable growth of dendritic Li, which incurs serious safety issues and poor electrochemical performance, hindering its practical applications. Herein, this study shows that uniform Li nucleation/growth can be induced by an ultralight 3D current collector consisting of in situ nitrogen‐doped graphitic carbon foams (NGCFs) to realize suppressing dendritic Li growth at the nucleating stage. The N‐containing functional groups guide homogenous growth of Li nucleus nanoparticles and the initial Li nucleus seed layer regulates the following well‐distributed Li growth. Benefiting from such favorable Li growth behavior, superior electrochemical performance can be achieved as evidenced by the high Coulombic efficiency (≈99.6% for 300 cycles), large capacity (10 mA h cm^?2, 3140 mA h g^?1_NGCF‐Li), and ultralong lifespan (>1200 h) together with low overpotential (<25 mV at 3 mA cm^?2); even under a high current density up to 10 mA cm^?2, it still displays low overpotential of 62 mV.     

Interlayered Dendrite‐Free Lithium Plating for High‐Performance Lithium‐Metal Batteries

For its high theoretical capacity and low redox potential, Li metal is considered to be one of the most promising anode materials for next‐generation batteries. However, practical application of a Li‐metal anode is impeded by Li dendrites, which are generated during the cycling of Li plating/stripping, leading to safety issues. Researchers attempt to solve this problem by spatially confining the Li plating. Yet, the effective directing of Li deposition into the confined space is challenging. Here, an interlayer is constructed between a graphitic carbon nitrite layer (g‐C₃N₄) and carbon cloth (CC), enabling site‐directed dendrite‐free Li plating. The g‐C₃N₄/CC as an anode scaffold enables extraordinary cycling stability for over 1500 h with a small overpotential of ≈80 mV at 2 mA cm^?2. Furthermore, prominent battery performance is also demonstrated in a full cell (Li/g‐C₃N₄/CC as anode and LiCoO₂ as cathode) with high Coulombic efficiency of 99.4% over 300 cycles.     

High Capacity,Dendrite‐Free Growth,and Minimum Volume Change Na Metal Anode

Na metal anode attracts increasing attention as a promising candidate for Na metal batteries (NMBs) due to the high specific capacity and low potential. However, similar to issues faced with the use of Li metal anode, crucial problems for metallic Na anode remain, including serious moss‐like and dendritic Na growth, unstable solid electrolyte interphase formation, and large infinite volume changes. Here, the rational design of carbon paper (CP) with N‐doped carbon nanotubes (NCNTs) as a 3D host to obtain Na@CP‐NCNTs composites electrodes for NMBs is demonstrated. In this design, 3D carbon paper plays a role as a skeleton for Na metal anode while vertical N‐doped carbon nanotubes can effectively decrease the contact angle between CP and liquid metal Na, which is termed as being “Na‐philic.” In addition, the cross‐conductive network characteristic of CP and NCNTs can decrease the effective local current density, resulting in uniform Na nucleation. Therefore, the as‐prepared Na@CP‐NCNT exhibits stable electrochemical plating/stripping performance in symmetrical cells even when using a high capacity of 3 mAh cm^?2 at high current density. Furthermore, the 3D skeleton structure is observed to be intact following electrochemical cycling with minimum volume change and is dendrite‐free in nature.     

Dendrite‐Free Lithium Deposition via a Superfilling Mechanism for High‐Performance Li‐Metal Batteries

Uncontrollable Li dendrite growth and low Coulombic efficiency severely hinder the application of lithium metal batteries. Although a lot of approaches have been developed to control Li deposition, most of them are based on inhibiting lithium deposition on protrusions, which can suppress Li dendrite growth at low current density, but is inefficient for practical battery applications, with high current density and large area capacity. Here, a novel leveling mechanism based on accelerating Li growth in concave fashion is proposed, which enables uniform and dendrite‐free Li plating by simply adding thiourea into the electrolyte. The small thiourea molecules can be absorbed on the Li metal surface and promote Li growth with a superfilling effect. With 0.02 m thiourea added in the electrolyte, Li | Li symmetrical cells can be cycled over 1000 cycles at 5.0 mA cm^?2, and a full cell with LiFePO₄ | Li configuration can even maintain 90% capacity after 650 cycles at 5.0 C. The superfilling effect is also verified by computational chemistry and numerical simulation, and can be expanded to a series of small chemicals using as electrolyte additives. It offers a new avenue to dendrite‐free lithium deposition and may also be expanded to other battery chemistries.     

Dendrite‐Free Sodium‐Metal Anodes for High‐Energy Sodium‐Metal Batteries

Sodium (Na) metal is one of the most promising electrode materials for next‐generation low‐cost rechargeable batteries. However, the challenges caused by dendrite growth on Na metal anodes restrict practical applications of rechargeable Na metal batteries. Herein, a nitrogen and sulfur co‐doped carbon nanotube (NSCNT) paper is used as the interlayer to control Na nucleation behavior and suppress the Na dendrite growth. The N‐ and S‐containing functional groups on the carbon nanotubes induce the NSCNTs to be highly “sodiophilic,” which can guide the initial Na nucleation and direct Na to distribute uniformly on the NSCNT paper. As a result, the Na‐metal‐based anode (Na/NSCNT anode) exhibits a dendrite‐free morphology during repeated Na plating and striping and excellent cycling stability. As a proof of concept, it is also demonstrated that the electrochemical performance of sodium–oxygen (Na–O₂) batteries using the Na/NSCNT anodes show significantly improved cycling performances compared with Na–O₂ batteries with bare Na metal anodes. This work opens a new avenue for the development of next‐generation high‐energy‐density sodium‐metal batteries.     

Regulating Lithium Nucleation via CNTs Modifying Carbon Cloth Film for Stable Li Metal Anode

Li metal is demonstrated as one of the most promising anode materials for high energy density batteries. However, uncontrollable Li dendrite growth and repeated growth of solid electrolyte interface during the charge/discharge process lead to safety issues and capacity decay, preventing its practical application. To address these issues, an effective strategy is to realize uniform Li nucleation. Here, a stable lithium–scaffold composite electrode (CC/CNT@Li) is designed by melting of lithium metal into 3D interconnected lithiophilic carbon nanotube (CNT) on a porous carbon cloth (CC). The 3D interconnected CNTs successfully change the lithiophobic CC into lithiophilic nature, reducing the polarization of the electrode, ensuring homogenous Li nucleation and continuous smooth Li plating. The CNTs on the surface of CC provide adequate Li nucleation sites and reduce the areal current density to avoid Li dendrite growth. The 3D porous structure of CC/CNT offers enough free room for buffering the huge volume change during Li plating/stripping. The CC/CNT@Li composite anode exhibits dendrite‐free morphology and superior cycling performances over 500 h with low voltage hysteresis of 18, 23, and 71 mV at the current density of 1, 2, and 5 mA cm^?2, respectively.     

Lithiophilic 3D Nanoporous Nitrogen‐Doped Graphene for Dendrite‐Free and Ultrahigh‐Rate Lithium‐Metal Anodes

The key bottlenecks hindering the practical implementations of lithium‐metal anodes in high‐energy‐density rechargeable batteries are the uncontrolled dendrite growth and infinite volume changes during charging and discharging, which lead to short lifespan and catastrophic safety hazards. In principle, these problems can be mitigated or even solved by loading lithium into a high‐surface‐area, conductive, and lithiophilic porous scaffold. However, a suitable material that can synchronously host a large loading amount of lithium and endure a large current density has not been achieved. Here, a lithiophilic 3D nanoporous nitrogen‐doped graphene as the sought‐after scaffold material for lithium anodes is reported. The high surface area, large porosity, and high conductivity of the nanoporous graphene concede not only dendrite‐free stripping/plating but also abundant open space accommodating volume fluctuations of lithium. This ingenious scaffold endows the lithium composite anode with a long‐term cycling stability and ultrahigh rate capability, significantly improving the charge storage performance of high‐energy‐density rechargeable lithium batteries.     

A Lightweight 3D Cu Nanowire Network with Phosphidation Gradient as Current Collector for High‐Density Nucleation and Stable Deposition of Lithium

Lithium metal anodes with high energy density are important for further development of next‐generation batteries. However, inhomogeneous Li deposition and dendrite growth hinder their practical utilization. 3D current collectors are widely investigated to suppress dendrite growth, but they usually occupy a large volume and increase the weight of the system, hence decreasing the energy density. Additionally, the nonuniform distribution of Li ions results in low utilization of the porous structure. A lightweight, 3D Cu nanowire current collector with a phosphidation gradient is reported to balance the lithiophilicity with conductivity of the electrode. The phosphide gradient with good lithiophilicity and high ionic conductivity enables dense nucleation of Li and its steady deposition in the porous structure, realizing a high pore utilization. Specifically, the homogenous deposition of Li leads to the formation of an oriented texture on the electrode surface at high capacities. A high mass loading (≈44 wt%) of Li with a capacity of 3 mAh cm^?2 and a high average Coulombic efficiency of 97.3% are achieved. A lifespan of 300 h in a symmetrical cell is obtained at 2 mA cm^?2, implying great potential to stabilize lithium metal.     

Horizontal Growth of Lithium on Parallelly Aligned MXene Layers towards Dendrite‐Free Metallic Lithium Anodes

Although metallic lithium is an extremely promising anode for lithium‐based batteries due to its high theoretical capacity, the uncontrollable growth of lithium dendrites, in particular under deep stripping and plating, have stagnated its application. It is demonstrated that parallelly aligned MXene (Ti₃C₂T_x ) layers enable the efficient guiding of lithium nucleation and growth on the surface of 2D MXene nanosheets, giving rise to horizontal‐growth lithium anodes. Moreover, the inherent fluorine terminations in MXene afford a uniform and durable solid electrolyte interface with lithium fluoride at the anode/electrolyte interface, efficiently regulating electromigration of lithium ions. Thus, a dendrite‐free lithium anode with a long cycle life up to 900 h and excellent deep stripping–plating capabilities up to 35 mAh cm^?2 is achieved, which can further serve as an anode for a lithium metal battery, exhibiting high cycle stability up to 1000 cycles.     

A 3D and Stable Lithium Anode for High‐Performance Lithium–Iodine Batteries

Lithium metal is considered as the most promising anode material due to its high theoretical specific capacity and the low electrochemical reduction potential. However, severe dendrite problems have to be addressed for fabricating stable and rechargeable batteries (e.g., lithium–iodine batteries). To fabricate a high‐performance lithium–iodine (Li–I₂) battery, a 3D stable lithium metal anode is prepared by loading of molten lithium on carbon cloth doped with nitrogen and phosphorous. Experimental observations and theoretical calculation reveal that the N,P codoping greatly improves the lithiophilicity of the carbon cloth, which not only enables the uniform loading of molten lithium but also facilitates reversible lithium stripping and plating. Dendrites formation can thus be significantly suppressed at a 3D lithium electrode, leading to stable voltage profiles over 600 h at a current density of 3 mA cm^?2. A fuel cell with such an electrode and a lithium–iodine cathode shows impressive long‐term stability with a capacity retention of around 100% over 4000 cycles and enhanced high‐rate capability. These results demonstrate the promising applications of 3D stable lithium metal anodes in next‐generation rechargeable batteries.     

3D Printed High‐Performance Lithium Metal Microbatteries Enabled by Nanocellulose

Batteries constructed via 3D printing techniques have inherent advantages including opportunities for miniaturization, autonomous shaping, and controllable structural prototyping. However, 3D‐printed lithium metal batteries (LMBs) have not yet been reported due to the difficulties of printing lithium (Li) metal. Here, for the first time, high‐performance LMBs are fabricated through a 3D printing technique using cellulose nanofiber (CNF), which is one of the most earth‐abundant biopolymers. The unique shear thinning properties of CNF gel enables the printing of a LiFePO₄ electrode and stable scaffold for Li. The printability of the CNF gel is also investigated theoretically. Moreover, the porous structure of the CNF scaffold also helps to improve ion accessibility and decreases the local current density of Li anode. Thus, dendrite formation due to uneven Li plating/stripping is suppressed. A multiscale computational approach integrating first‐principle density function theory and a phase‐field model is performed and reveals that the porous structures have more uniform Li deposition. Consequently, a full cell built with a 3D‐printed Li anode and a LiFePO₄ cathode exhibits a high capacity of 80 mA h g^?1 at a charge/discharge rate of 10 C with capacity retention of 85% even after 3000 cycles.     

Lithiophilic Cu‐CuO‐Ni Hybrid Structure: Advanced Current Collectors Toward Stable Lithium Metal Anodes

Metallic lithium (Li) is a promising anode material for next‐generation rechargeable batteries. However, the dendrite growth of Li and repeated formation of solid electrolyte interface during Li plating and stripping result in low Coulombic efficiency, internal short circuits, and capacity decay, hampering its practical application. In the development of stable Li metal anode, the current collector is recognized as a critical component to regulate Li plating. In this work, a lithiophilic Cu‐CuO‐Ni hybrid structure is synthesized as a current collector for Li metal anodes. The low overpotential of CuO for Li nucleation and the uniform Li⁺ ion flux induced by the formation of Cu nanowire arrays enable effective suppression of the growth of Li dendrites. Moreover, the surface Cu layer can act as a protective layer to enhance structural durability of the hybrid structure in long‐term running. As a result, the Cu‐CuO‐Ni hybrid structure achieves a Coulombic efficiency above 95% for more than 250 cycles at a current density of 1 mA cm^?2 and 580 h (290 cycles) stable repeated Li plating and stripping in a symmetric cell.     

A Triple‐Gradient Host for Long Cycling Lithium Metal Anodes at Ultrahigh Current Density

The viable Li metal anodes (LMAs) are still hampered by the safety concerns resulting from fast Li dendrite growth and huge volume expansion during cycling. Herein, carbon nanofiber matrix anchored with MgZnO nanoparticles (MgZnO/CNF) is developed as a flexible triple‐gradient host for long cycling LMAs. The superlithiophilic MgZnO nanoparticles significantly increase the wettability of CNF for fast and homogeneous infusion with molten Li. The in‐built potential and lithiophilic gradients constructed after an in situ lithiation of MgZnO and CNF enable nearly zero Li nucleation overpotential and homogeneous deposition of lithium at different scales. As such, the LMAs based on MgZnO/CNF achieve long cycling life and small overpotential even at a record‐high current density of 50 mA cm^?2 and a high areal capacity of 10 mAh cm^?2. A full cell paring with this designed LMA and LiFePO₄ exhibits a capacity retention up to 82% after 600 cycles at a high rate of 5 C. A Li‐ion capacitor also shows an impressive capacity retention of 84% at 5 A g^?1 after 10 000 cycles. Such a Li@MgZnO/CNF anode is a promising candidate for Li‐metal energy storage systems, especially working under ultrahigh current density.