Lithiophilic Hydrogen-Substituted Graphdiyne Aerogels with Ionically Conductive Channels for High-Performance Lithium Metal Batteries.

Lithium (Li) metal stands as a promising anode in advancing high-energy-density batteries. However, intrinsic issues associated with metallic Li, especially the dendritic growth, have hindered its practical application. Herein, we focus on molecular combined structural design to develop dendrite-free anodes. Specifically, using hydrogen-substituted graphdiyne (HGDY) aerogel hosts, we successfully fabricated a promising Li composite anode (Li@HGDY). The HGDY aerogel's lithiophilic nature and hierarchical pores drive molten Li infusion and reduce local current density within the three-dimensional HGDY host. The unique molecular structure of HGDY provides favorable bulk pathways for lithium-ion transport. By simultaneous regulation of electron and ion transport within the HGDY host, uniform lithium stripping/platting is fulfilled. Li@HGDY symmetric cells exhibit a low overpotential and stable cycling. The Li@HGDY||lithium iron phosphate full cell retained 98.1% capacity after 170 cycles at 0.4 C. This study sheds new light on designing high-capacity and long-lasting lithium metal anodes.

Molecular-Level Anion and Li+ Co-Regulation by Amphoteric Polymer Separator for High-Rate Stable Lithium Metal Anode.

Regulating ion transport is a prevailing strategy to suppress lithium dendrite growth, in which the distribution of ion regulatory sites plays an important role. Here a hyperbranched polyamidoamine (HBPA) grafted polyethylene (PE) composite separator (HBPA-g-PE) is reported. The densely and uniformly distributed positive -NH2 and negative -CHNO- groups efficiently restrict the anion migration and promote Li+ transport at the surface of the lithium metal anode. The obtained Li foil symmetric cell delivers a stable cycle performance with a low-voltage hysteresis of 130 mV for over 1500 h (3000 cycles) at an ultrahigh current density of 20 mA cm-2 and a practical areal capacity of 5 mAh cm-2. Moreover, HBPA-g-PE separator enables a practical lithium-sulfur battery to achieve over 200-cycle stable performance with initial and retained capacity of 700 and 455 mAh g-1, at a high sulfur loading of 4 mg cm-2 and a low electrolyte content/sulfur loading ratio of 8 µL mg-1.

Rapidly Prepared Lithophilic Frameworks Stabilizes Lithium Anodes via Altered Lithium Deposition Patterns.

Lithium metal batteries are regarded as promising candidates for next-generation energy storage systems. However, their anodes are susceptible to interfacial instability due to significant volume changes, which significantly impacts the cycle life of lithium metal batteries. Here, a rapid method for the fabrication of 3D-hosts with interface modified layers is reported. A simple infiltration and heating process enables the transformation of copper foam into Zn-BDC-modified copper foam within 1 min, rendering it suitable for use as a current collector for lithium metal anodes. The Zn-BDC nanosheets with high lithiophilicity are uniformly distributed on the surface of the current collector, facilitating the uniform deposition of lithium and reducing the volume change. Consequently, the half cell exhibits a remarkably low overpotential (26 mV) at a current-density of 4 mA cm-2 and is cycled stably for 1000 h. Furthermore, it demonstrates a significant enhancement in performance in the LiFePO4 full cell. This study provides a crucial reference on the connection between the interfacial modification of the current collector and the lithium deposition behavior, which promotes the practicalization of lithium metal anodes.

Stable Lithium Metal Batteries Enabled by Lithiophilic Core-Shell Nanowires on Copper Foam.

Lithium (Li) metal batteries have attracted considerable research attention due to their exceptionally high theoretical capacity. However, the commercialization of Li metal batteries faces challenges, primarily attributed to uncontrolled growth of Li dendrites, which raises safety concerns and lowers coulombic efficiency. To mitigate Li dendrites growth and attain dense Li deposition, the hybrid SiO2-Cu2O lithiophilic film applied to a 3D copper foam current collector is developed to regulate the interfacial properties for achieving even and dense Li deposition. The SiO2-Cu2O possesses strong Li+ trapping capability through strong lithiophilicity from Cu2O. Additionally, the SiO2-Cu2O enables uniform ion diffusion through the domain-limiting effect of the holes in the SiO2 layer, inducing an even and dense Li plating/stripping behavior at a large capacity. Furthermore, the SiO2 layer promotes the formation of an initial high inorganic content Solid Electrolyte Interphase (SEI) through selective preferential binding with anion and solvent molecules. When the SiO2-Cu2O@Li anode is coupled with a LiFePO4 (LFP) cathode, the resulting full cell exhibits superior cycling stability and rate performance. These results provide a facile approach to construct a lithiophilic current collector for practical Li metal anodes.

Trinitarian Design of Gradient Artificial Interphase Enables Colossal Granular Li Deposits for Stable Li-Metal Batteries.

The cycling lifespan of Li-metal batteries is compromised by the unstable solid electrolyte interphase (SEI) and the continuous Li dendrites, restricting their practical implementations. Given these challenges, establishing an artificial SEI holds promise. Herein, a trinitarian gradient interphase is innovatively designed through composite coatings of magnesium fluoride (MgF2), N-hexadecyltrimethylammonium chloride (CTAC), and polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP) on Li-metal anode (LMA). Specifically, the MgF2/CTAC/PVDF-HFP SEI spontaneously forms a lithium fluoride (LiF)-rich PVDF-HFP-based SEI, along with lithium-magnesium (Li-Mg) alloy substrate as lithiophilic electronic conductor and positively charged CTAC during plating. Noticeably, the Li-Mg alloy homogenizes the distribution of electric field and reduce the internal resistance, while the electronically insulated LiF/PVDF-HFP composite SEI offers fast ion-conducting and mechanical flexibility, accommodating the volumetric expansion and ensuring stable Li-ion flux. Additionally, CTAC at the dendritic tip is pivotal for mitigating dendrites through its electrostatic shield mechanism. Innovatively, this trinitarian synergistic mechanism, which facilitates colossal granular Li deposits, constructs a dendrite-free LMA, leading to stable cycling performances in practical Li||LFP, popular Li||NCM811, and promising Li||S full cells. This work demonstrates the design of multifunctional composite SEI for comprehensive Li protection, thereby inspiring further advancements in artificial SEI engineering for alkali-metal batteries.

A 3D Lithiophilic Host for Dendrite-Free Lithium Metal Anode via One-Step Carbonization of an Energetic Metal-Organic Framework.

Low Coulombic efficiency (CE) and safety issues are huge problems that hinder the practical application of Li metal anodes. Constructing Li host structures decorated with functional species can restrain the growth of Li dendrites and alleviate the great volume change. Here, a 3D porous carbonaceous skeleton modified with rich lithiophilic groups (Zn, ZnO, and Zn(CN)2 ) is synthesized as a Li host via one-step carbonization of a triazole-containing metal-organic framework. The nano lithiophilic groups serve as preferred sites for Li nucleation and growth, regulating a uniform Li+ flux and uniform current density distribution. In addition, the 3D porous network functions as a Li reservoir that provides rich internal space to store Li, thus alleviating the volumetric expansion during Li plating/stripping process. Thanks to these component and structural merits, an ultra-low overpotential for Li deposition is achieved, together with high CE of over 99.5% for more than 500 cycles at 1 mA cm-2 and 1 mAh cm-2 in half cells. The symmetric cells exhibit a prolonged cycling of 900 h at 1 mA cm-2 . The full cells by coupling Zn/ZnO/Zn(CN)2 @C-Li anode with LiFePO4 cathode deliver a high capacity retention of 94.3% after 200 cycles at 1 C.

Structural Design of 3D Current Collectors for Lithium Metal Anodes: A Review.

Due to the ultrahigh theoretical specific capacity (3860 mAh g-1) and low redox potential (-3.04 V vs. standard hydrogen electrode), Lithium (Li) metal anode (LMA) received increasing attentions. However, notorious dendrite and volume expansion during the cycling process seriously hinder the development of high energy density Li metal batteries. Constructing three-dimensional (3D) current collectors for Li can fundamentally solve the intrinsic drawback of hostless for Li. Therefore, this review systematically introduces the design and synthesis engineering and the current development status of different 3D collectors in recent years (the current collectors are divided into two major parts: metal-based current collectors and carbon-based current collectors). In the end, some perspectives of the future promotion for LMA application are also presented.

High Rate and Low-Temperature Stable Lithium Metal Batteries Enabled by Lithiophilic 3D Cu-CuSn Porous Framework.

Lithium (Li) metal is regarded as the "Holy Grail" of anodes for high-energy rechargeable lithium batteries by virtue of its ultrahigh theoretical specific capacity and the lowest redox potential. However, the Li dendrite impedes the practical application of Li metal anodes. Herein, lithiophilic three-dimensional Cu-CuSn porous framework (3D Cu-CuSn) was fabricated by a vapor phase dealloying strategy via the difference in saturated vapor pressure between different metals and the Kirkendall effect. CuSn alloy sites were converted into LiSn alloy sites through the molten Li infusion method, and composite Li metal anodes (3D Cu-LiSn-Li) are achieved. Alloyed tin, as the bridge between the porous copper substrate and metallic Li, plays a critical role in optimizing Li nucleation and enhancing the fast lithium migration kinetics. This work demonstrates that lithiophilic binary copper alloys are an effective way to achieve room-temperature high rate performance and satisfied low-temperature cycling stability for Li metal batteries.

Sulfonyl Molecules Induced Oriented Lithium Deposition for Long-Term Lithium Metal Batteries.

Dendrites growth and unstable interfacial Li+ transport hinder the practical application of lithium metal batteries (LMBs). Herein, we report an active layer of 2,4,6-trihydroxy benzene sulfonyl fluorine on copper substrate that induces oriented Li+ deposition and generates highly crystalline solid-electrolyte interphase (SEI) to achieve high-performance LMBs. The lithiophilic -SO2 - groups of highly crystalline SEI accept the rapidly transported Li+ ions and form a dense inner layer of LiF and Li3 N, which regulate Li+ plating morphology along the (110) crystal surface toward dendrite-free Li anode. Thus, Li||Cu cells with lithiophilic SEI achieve an average deposition efficiency of 99.8 % after 700 cycles, and Li||Li cells operate well for 1100 h. Besides, Li||LiNi0.8 Co0.1 Mn0.1 O2 cells with modified SEI exhibit a capacity retention that is 14 times than that of conventional SEI. Even at -60 °C, Li||Cu cells reach stable deposition efficiency of 83.2 % after 100 cycles.

Lithiophilic Nanowire Guided Li Deposition in Li Metal Batteries.

Lithium (Li) metal batteries (LMBs) provide superior energy densities far beyond current Li-ion batteries (LIBs) but practical applications are hindered by uncontrolled dendrite formation and the build-up of dead Li in "hostless" Li metal anodes. To circumvent these issues, we created a 3D framework of a carbon paper (CP) substrate decorated with lithiophilic nanowires (silicon (Si), germanium (Ge), and SiGe alloy NWs) that provides a robust host for efficient stripping/plating of Li metal. The lithiophilic Li22 Si5 , Li22 (Si0.5 Ge0.5 )5, and Li22 Ge5 formed during rapid Li melt infiltration prevented the formation of dead Li and dendrites. Li22 Ge5 /Li covered CP hosts delivered the best performance, with the lowest overpotentials of 40 mV (three times lower than pristine Li) when cycled at 1 mA cm-2 /1 mAh cm-2 for 1000 h and at 3 mA cm-2 /3 mAh cm-2 for 500 h. Ex situ analysis confirmed the ability of the lithiophilic Li22 Ge5 decorated samples to facilitate uniform Li deposition. When paired with sulfur, LiFePO4, and NMC811 cathodes, the CP-LiGe/Li anodes delivered 200 cycles with 82%, 93%, and 90% capacity retention, respectively. The discovery of the highly stable, lithiophilic NW decorated CP hosts is a promising route toward stable cycling LMBs and provides a new design motif for hosted Li metal anodes.

Lithiophilic Magnetic Host Facilitates Target-Deposited Lithium for Practical Lithium-Metal Batteries.

Lithium-metal shows promising prospects in constructing various high-energy-density lithium-metal batteries (LMBs) while long-lasting tricky issues including the uncontrolled dendritic lithium growth and infinite lithium volume expansion seriously impede the application of LMBs. In this work, it is originally found that a unique lithiophilic magnetic host matrix (Co3 O4 -CCNFs) can simultaneously eliminate the uncontrolled dendritic lithium growth and huge lithium volume expansion that commonly occur in typical LMBs. The magnetic Co3 O4 nanocrystals which inherently embed on the host matrix act as nucleation sites and can also induce micromagnetic field and facilitate a targeted and ordered lithium deposition behavior thus, eliminating the formation of dendritic Li. Meanwhile, the conductive host can effectively homogenize the current distribution and Li-ion flux, thus, further relieving the volume expansion during cycling. Benefiting from this, the featured electrodes demonstrate ultra-high coulombic efficiency of 99.1% under 1 mA cm-2 and 1 mAh cm-2 . Symmetric cell under limited Li (10 mAh cm-2 ) inspiringly delivers ultralong cycle life of 1600 h (under 2 mA cm-2 , 1 mAh cm-2 ). Moreover, LiFePO4 ||Co3 O4 -CCNFs@Li full-cell under practical condition of limited negative/positive capacity ratio (2.3:1) can deliver remarkably improved cycling stability (with 86.6% capacity retention over 440 cycles).

Utilizing Ultra-homogeneous SiOx and Defects to Achieve Interlayer Protection for Lithium Metal Anodes.

The uncontrollable growth and uneven nucleation of lithium metal can be addressed by utilizing spatial confinement structures in conjunction with lithiophilic sites. However, their complex fabrication technique and the inhomogeneous dispersion of lithiophilic sites make the application ineffective. In this work, ultra-uniformly dispersed SiOx seeds and defects are produced in situ to achieve the spatially restricted protection within the reduced graphene oxide (rGO) layer. The in situ formed SiOx and defects during annealing double constrain lithium nucleation and growth behaviors thanks to the superlithiophilic characteristic, while both provide the fast Li+ transport channel to utilize the interlayer protection of rGO in limiting lithium dendrite growth. Furthermore, XANES and XPS analyze the SiOx seeds that are dominated by various valence states, and theoretical calculations further verify the control on the nucleation of lithium atoms. Benefiting from the optimum average valence of three for the "control site", the host realizes steady circulation. In asymmetric cells, the host demonstrates excellent coulombic efficiency of 99.1% and stable lifespans over 1250 h at 1 mA cm-2 . When assembled in LiFePO4 full cells, it retains a favorable capacity of 116.2 mA h g-1 after 170 cycles.

Ultrathin Lithiophilic 3D Arrayed Skeleton Enabling Spatial-Selection Deposition for Dendrite-Free Lithium Anodes.

Lithium metal batteries are promising to become a new generation of energy storage batteries. However, the growth of Li dendrites and the volume expansion of the anode are serious constraints to their commercial implementation. Herein, a controllable strategy is proposed to construct an ultrathin 3D hierarchical host of honeycomb copper micromesh loaded with lithiophilic copper oxide nanowires (CMMC). The uniquely designed 3D hierarchical arrayed skeletons demonstrate a surface-preferred and spatial-selective effect to homogenize local current density and relieve the volume expansion, effectively suppressing the dendrite growth. Employing the constructed CMMC current collector in a half-cell, >400 cycles with 99% coulombic efficiency at 0.5 mA cm-2 is performed. The symmetric battery cycles stably for >2000 h, and the full battery delivers a capacity of 166.6 mAh g-1 . This facile and controllable approach provides an effective strategy for constructing high-performance lithium metal batteries.

A Gradient Lithiophilic Structure for Stable Lithium Metal Anodes with Ultrahigh Rate and Ultradeep Capacity.

Using three-dimensional current collectors (3DCC) as frameworks for lithium metal anodes (LMAs) is a promising approach to inhibit dendrite growth. However, the intrinsically accumulated current density on the top surface and limited Li-ion transfer in the interior of 3DCC still lead to the formation of lithium dendrites, which can pose safety risks. In this study, it reports that gradient lithiophilic structures can induce uniform lithium deposition within the interior of the 3DCC, greatly suppressing dendrite formation, as confirmed by COMSOL simulations and experimental results. With this concept, a gradient-structured zinc oxide-loaded copper foam (GSZO-CF) is synthesized via an easy solution-combustion method at low cost. The resulting Li@GSZO-CF symmetric cells demonstrate stable cycling performance for over 800 cycles, with an ultra-deep capacity of 10 mAh cm-2 even under an ultra-high current density of 50 mA cm-2 , the top results reported in the literature. Moreover, when combined with a LiFePO4 (LFP) cathode under a low negative/positive (N/P) capacity ratio of 2.9, the Li@GSZO-CF||LFP full cells exhibit stable performance for 200 cycles, with a discharge capacity of 130 mAh g-1 and retention of 85.5% at a charging/discharging rate of 1C. These findings suggest a promising strategy for the development of new-generation LMAs.

Flattening of Lithium Plating in Carbonate Electrolytes Enabled by All-In-One Separator.

The uncontrollable dendritic growth of metallic lithium during repeated cycling in carbonate electrolytes is a crucial obstacle hindering the practical use of Li-metal batteries (LMBs). Among numerous approaches proposed to mitigate the intrinsic constraints of Li metal, the design of a functional separator is an attractive approach to effectively suppress the growth of Li dendrites because direct contact with both the Li metal surface and the electrolyte is maintained. Here, a newly designed all-in-one separator containing bifunctional CaCO3 nanoparticles (CPP separator) is proposed to achieve the flattening of Li deposits on the Li electrode. Strong interactions between the highly polar CaCO3 nanoparticles and the polar solvent reduces the ionic radius of the Li+ -solvent complex, thus increasing the Li+ transference number and leading to a reduced concentration overpotential in the electrolyte-filled separator. Furthermore, the integration of CaCO3 nanoparticles into the separator induces the spontaneous formation of mechanically-strong and lithiophilic CaLi2 at the Li/separator interface, which effectively decreases the nucleation overpotential toward Li plating. As a result, the Li deposits exhibit dendrite-free planar morphologies, thus enabling excellent cycling performance in LMBs configured with a high-Ni cathode in a carbonate electrolyte under practical operating conditions.

Enhanced Cyclability of Lithium Metal Anodes Enabled by Anti-aggregation of Lithiophilic Seeds.

Constructing 3D skeletons modified with lithiophilic seeds has proven effective in achieving dendrite-free lithium metal anodes. However, these lithiophilic seeds are mostly alloy- or conversion-type materials, and they tend to aggregate and redistribute during cycling, resulting in the failure of regulating Li deposition. Herein, we address this crucial but long-neglected issue by using intercalation-type lithiophilic seeds, which enable antiaggregation owing to their negligible volume expansion and high electrochemical stability against Li. To exemplify this, a 3D carbon-based host is built, in which ultrafine TiO2 seeds are uniformly embedded in nitrogen-doped hollow porous carbon spheres (N-HPCSs). The TiO2@N-HPCSs electrode exhibits superior Coulombic efficiency, high-rate capability, and long-term stability when evaluated as compertitive anodes for Li metal batteries. Furthermore, the superiority of intercalation-type seeds is comprehensively revealed through controlled experiments by various in situ/ex situ electron and optical microscopies, which highlights the excellent structural stability and lithiophilicity of TiO2 nanoseeds upon repeated cycling.

Highly Efficient Organosulfur and Lithium-Metal Hosts Enabled by C@Fe3 N Sponge.

Lithium-organosulfur (Li-OS) batteries, despite possessing high theoretical specific capacity, encounter a few practical challenges, including unsatisfactory lifespan and low active material utilization under realistic conditions. Here, diisoropyl xanthogen polysulfide (DIXPS) has been selected as a model organosulfur compound to investigate the practical feasibility of Li-OS batteries under realistic conditions. A well-designed freestanding carbon sponge decorated with Fe3 N nanoparticles (C@Fe3 N) is introduced into the Li-OS cells as a scaffold for both Li and DIXPS. The lithiophilic property of the C@Fe3 N host guides uniform lithium deposition at the anode, and the catalysis of the DIXPS conversion reaction promotes the kinetics at the cathode. Impressively, the synergistic effect of C@Fe3 N leads to an extremely stable cycling performance over 1 000 cycles in a Li-OS full cell under realistic conditions.

In-Situ Constructing A Heterogeneous Layer on Lithium Metal Anodes for Dendrite-Free Lithium Deposition and High Li-ion Flux.

Constructing efficient artificial solid electrolyte interface (SEI) film is extremely vital for the practical application of lithium metal batteries. Herein, a dense artificial SEI film, in which lithiophilic Zn/Lix Zny are uniformly but nonconsecutively dispersed in the consecutive Li+ -conductors of Lix SiOy , Li2 O and LiOH, is constructed via the in situ reaction of layered zinc silicate nanosheets and Li. The consecutive Li+ -conductors can promote the desolvation process of solvated-Li+ and regulate the transfer of lithium ions. The nonconsecutive lithiophilic metals are polarized by the internal electric field to boost the transfer of lithium ions, and lower the nucleation barrier. Therefore, a low polarization of ≈50 mV for 750 h at 2.0 mA cm-2 in symmetric cells, and a high capacity retention of 99.2 % in full cells with a high lithium iron phosphate areal loading of ≈13 mg cm-2 are achieved. This work offers new sights to develop advanced alkali metal anodes for efficient energy storage.

Built-In Stable Lithiophilic Sites in 3D Current Collectors for Dendrite Free Li Metal Electrode.

Stable lithiophilic sites in 3D current collectors are the key to guiding the uniform Li deposition and thus suppressing the Li dendrite growth, but such sites created by the conventional surface decoration method are easy to be consumed along with cycling. In this work, carbon fiber (CF)-based 3D porous networks with built-in lithiophilic sites that are stable upon cycling are demonstrated. Such heterostructured architecture is constructed by the introduction of zeolitic imidazolate framework-8-based nanoparticles during the formation of the 3D fibrous carbonaceous network and the following annealing. The introduced Zn species are found to be re-distributed along the entire individual CF in the 3D network, and function as lithiophilic sites that favor the homogenous lithium nucleation and growth. The 3D network also presents a multi-scale porous structure that improves the space utilization of the host. The corresponding symmetric cells adopting such 3D anode demonstrate excellent cycling performance, especially at a high rate (300 cycles at 10 mA cm-2 with a capacity of 5 mA h cm-2 ). A full cell with LiFePO4 cathode shows a capacity retention of 98% after cycling at 1C for 300 cycles. This method provides an effective design strategy for 3D hosting electrodes in dendrite-free alkali metal anode applications.

Bidirectional Lithiophilic Gradients Modification of Ultralight 3D Carbon Nanofiber Host for Stable Lithium Metal Anode.

Using 3D host is an effective way to solve the dendrite growth problem and accommodate volume changes of lithium (Li) metal anode. However, the preferred Li deposition on the top surface leads to the Li metal agglomeration at the surface. In addition, the large weight of the 3D host also greatly decreases the capacity based on the whole anode. Herein, a bidirectional lithiophilic gradient modification, including a top-down ZnO gradient and a bottom-up Sn gradient, is applied to an ultralight 3D carbon nanofiber host (density: 0.1 g cm-3 ) and ensures the evenly filling lithium deposition in the 3D host. ZnO transforms into highly ionic conductive Li-Zn alloy and Li2 O during cycling, enhancing the Li-ion transportation from top to bottom. The metallic Sn also lowers the Li nucleation potential, guiding the preferential Li deposition from the bottom. With such a host, a stable CE of 97.5% over 100 cycles at 1 mA cm-2 and 3 mAh cm-2 is achieved, and the full battery also delivers good cycling stability over 300 cycles with a high CE of 99.8% coupled with high loading LiFePO4 cathode (10 mg cm-2 ) and low N/P ratio (≈3).