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.

Functionalizing Separator by Coating a Lithiophilic Metal for Dendrite-Free Anode-free Lithium Metal Batteries

A stable anode-free lithium metal battery (AFLMB) is accomplished by the adoption of a facile fabricated amorphous antimony (Sb)-coated separator (SbSC). The large specific surface area of the separator elevates lithium (Li)-Sb alloy kinetic, improving Li wetting ability on pristine copper current collector (Cu). When tested with LiNi0.8 Mn0.1 Co0.1 O2 (NMC811) as cathode, the full cell with SbSC demonstrates low nucleation overpotential with compact, dendrite-free and homogeneous Li plating, and exhibits a notable lithium inventory retention rate (LIRR) of 99.8 % with capacity retention of 93.6 % after 60 cycles at 0.5 C-rate. Conversely, full cells containing pristine separator/Cu (i. e., SC) and pristine separator/Sb-coated current collector (i. e., SSbC) display poor cycling performances with low LIRRs. Density functional theory corroborates the nucleation behaviours observed during in-situ half-cell Li deposition. Functionalizing polymeric separator by metallic coating in AFLMB is a novel approach in improving the cycle life of an AFLMB by promoting homogeneous Li plating behavior. This innovative approach exemplifies a promising applicability for uniform Li-plating behavior to achieve a longer cycle life in AFLMB.

Ultra-Sleek High Entropy Alloy Tights: Realizing Superior Cyclability for Anode-Free Battery

The development of Li-free anodes to inhibit Li dendrite formation and provide high energy density Li batteries is highly applauded. However, the lithiophobic interphase and heterogeneous Li deposition hindered the practical application. In this work, a 20 nm ultra-sleek high entropy alloy (HEA, NiCdCuInZn) tights loaded with HEA nanoparticles are developed by a thermodynamically driven phase transition method on the carbon fiber (HEA/C). Multiple Li+ transport paths and abundant active sites are enabled by the cocktail effect of different constituent elements in HEA. These active sites with gradient absorption energies (-3.18 to -2.03 eV) facilitate selective binding, providing a low barrier for homogeneous Li nucleation. Simultaneously, multiple transport paths promote Li diffusion behavior with uniform Li deposition. Thus, the HEA/C achieves high reversibility of Li plating/stripping processes over 2000 cycles with a coulombic efficiency of 99.6% at 5 mA cm-2 /1 mAh cm-2 in asymmetric cells, as well as over 7200 h at 60 mA cm-2 /60 mAh cm-2 in symmetric cells. Moreover, the anode-free full cell with the HEA/C host has an average coulombic efficiency of 99.5% at 1 C after 160 cycles. This advanced HEA structure design shows a favorable potential application for anode-free Li metal batteries.

Three-Dimensional Octahedral Nanocrystals of Cu2O/CuF2 Grown on Porous Cu Foam Act as a Lithophilic Skeleton for Dendrite-Free Lithium Metal Anode

Metallic-lithium (Li) anodes are highly sought-after for next-generation energy storage systems due to their high theoretical capacity and low electrochemical potential. However, the commercialization of Li anodes faces challenges, including uncontrolled dendrite growth and volume changes during cycling. To address these issues, we developed a novel three-dimensional (3D) copper current collector. Here, we propose a two-step method to fabricate Cu2O/CuF2 octahedral nanocrystals (ONCs) onto 3D Cu current collectors. The resulting Cu foam with distributed ONCs provides active electrochemical sites, promoting uniform Li nucleation and dendrite-free Li deposition. The stable Cu2O/CuF2 ONCs@CF metallic current collector serves as a reliable host for dendrite-free lithium metal anodes. Additionally, the highly porous copper foam with a preconstructed conductive framework of Cu2O/CuF2 ONCs@CF effectively reduces local current density, suppressing volume changes during Li stripping and plating. The symmetric cell using Cu2O/CuF2 ONCs@CF metallic current collector exhibits excellent stability, maintaining over 1600 h at 1 mA cm-2 and a highly stable Coulombic efficiency of 98% over 100 cycles at the same current density, outperforming Li@CuF metallic current collectors. Furthermore, in a full-cell configuration paired with nickel-rich layered oxide cathode materials (Li@Cu2O/CuF2 ONCs@CF//NMC-811), the proposed setup demonstrates exceptional rate performance and an extended cycle life. In conclusion, our work presents a promising strategy to address Li anode challenges and highlights the exceptional performance of the Cu2O/CuF2 ONCs@CF metallic current collector, offering potential for high-capacity and long-lasting lithium-based energy storage systems.

Metal-Organic-Framework-Derived 3D Hierarchical Matrixes for High-Performance Flexible Li-S Batteries

Lithium-sulfur (Li-S) batteries have shown exceptional theoretical energy densities, making them a promising candidate for next-generation energy storage systems. However, their practical application is limited by several challenging issues, such as uncontrollable Li dendrite growth, sluggish electrochemical kinetics, and the shuttling effect of lithium polysulfides (LiPSs). To overcome these issues, we designed and synthesized hierarchical matrixes on carbon cloth (CC) by using metal-organic frameworks (MOFs). ZnO nanosheet arrays were used as anode hosts (CC-ZnO) to enable stable Li plating and stripping. The symmetric cell with CC-ZnO@Li was demonstrated to have enhanced cycling stability, with a voltage hysteresis of ∼25 mV for over 800 h at 1 mA cm^-2 and 1 mAh cm^-2. To address the cathode challenges, we developed a multifunctional CC-NC-Co cathode host with physical confinement, chemical anchoring, and excellent electrocatalysis. The full cells with CC-ZnO@Li anodes and CC-NC-Co@S cathodes exhibited excellent electrochemical performance, with long cycling life (0.02% and 0.03% capacity decay per cycle when cycling 900 times at 0.5 C and 600 times at 1 C, respectively) and outstanding rate performance (793 mAh g^-1 at 4 C). Additionally, the pouch cell based on the flexible CC-ZnO@Li anode and CC-NC-Co@S cathode showed good stability in different bending states. Overall, our study presents an effective strategy for preparing flexible Li and S hosts with hierarchical structures derived from MOF, which can pave the way for high-performance Li-S batteries.

Spontaneous In Situ Formation of Lithium Metal Nitride in the Interface of Garnet-Type Solid-State Electrolyte by Tuning of Molten Lithium

All-solid-state lithium-ion batteries (ASSLIBs) have attracted much attention owing to their high energy density and safety and are known as the most promising next-generation LIBs. The biggest advantage of ASSLIBs is that it can use lithium metal as the anode without any safety concerns. This study used a high-conductivity garnet-type solid electrolyte (Li6.75La3Zr1.75Ta0.25O12, LLZTO) and Li-Ga-N composite anode synthesized by mixing melted Li with GaN. The interfacial resistance was reduced from 589 to 21 Ω cm2, the symmetry cell was stably cycled for 1000 h at a current density of 0.1 mA cm-2 at room temperature, and the voltage range only changed from ±30 to ±40 mV. The full cell of Li-Ga-N|LLZTO|LFP exhibited a high first-cycle discharge capacity of 152.2 mAh g-1 and Coulombic efficiency of 96.5% and still maintained a discharge capacity retention of 91.2% after 100 cycles. This study also demonstrated that Li-Ga-N had been shown as two layers. Li3N shows more inclined to be closer to the LLZTO side. This method can help researchers understand what interface improvements can occur to enhance the performance of all-solid-state batteries in the future.

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 (Si_0.5 Ge_0.5 )_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, LiFePO_4, 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.

Uniform Deposition of Li-Metal Anodes Guided by 3D Current Collectors with In Situ Modification of the Lithiophilic Matrix

The lithium (Li)-metal anode is deemed as the "holy gray" of the next-generation Li-metal system because of its high theoretical specific capacity, minimal energy density, and lowest standard electrode potential. Nevertheless, its commercial application has been limited by the large volume variation during charge and discharge, the unstable interface between the Li metal and electrolyte, and uneven deposition of Li. Herein, we present a 3D host (Cu) with lithiophilic matrix (CuO and SnO₂) in situ modification via a facile ammonia oxidation method to serve as a current collector for the Li-metal anode. The 3D Cu host embellished by CuO and SnO₂ is abbreviated as 3D CSCC. By increasing interfacial activity, lowering the nucleation barrier, and accommodating changes in volume of the Li metal, the 3D CSCC electrode effectively demonstrates a homogeneous and dendrite-free deposition morphology with an excellent cycling performance up to 3000 h at a 1.0 mA cm^-2 current density. Additionally, the full cells paired with Li@3D CSCC anodes and LiCoO₂ cathodes show good capacity retention performance at 0.2 C.

Ultrafast Microwave Polarizing Electrons to Form Vertically Aligned Metal Hybrids as Lithiophilic Buffer for Lithium-Metal Batteries

Lithium-metal batteries (LMBs) have attracted great attention because of their high theoretical capacity and low electrochemical potential. However, uncontrollable Li dendrite growth and significant volume expansion result in safety issues that largely limit their practical applications. Herein, we explore a microwave-assisted strategy for the rapid synthesis of vertically aligned metal hybrids on Cu foil (VAMH@CF). Such an elaborate architecture of VAMH provides a lithiophilic buffer layer after prelithiation, offering vast nucleation sites/seeds for Li deposition (Li@VAMH@CF) and lower nucleation overpotential. Consequently, Li@VAMH@CF exhibits an outstanding cyclability with a long lifespan (up to 5500 cycles) and a low voltage hysteresis (28 mV) in a symmetrical cell at 3 mA cm^-2. LiFePO₄||Li@VAMH@CF full cells deliver a reversible capacity of about 140 mAh g^-1 for 200 cycles, further demonstrating opportunities of the microwave-involved strategy for optimizing Li-metal anodes.

Three-Dimensional Ordered Macro/Mesoporous Cu/Zn as a Lithiophilic Current Collector for Dendrite-Free Lithium Metal Anode

Li dendrites are considered as the primary cause for degradation and inevitable short circuit in lithium-metal batteries (LMBs). Although contemporary strategies have shown potential for addressing dendrite growth, none have achieved complete elimination. In this paper, a dendrite-free, three-dimensional, ordered, macro/mesoporous Cu/Zn current collector was prepared using a combination of simple colloidal crystal template and electrochemical method (electrodeposition and pulse plating). When paired with a hierarchically structured mesoporous (20-50 nm) and macroporous (450 nm) anode, this novel current collector achieved stable charge/discharge cycles of over 2000 h and a small plating/stripping potential (≈8 mV) at a current density of 0.2 mA cm^-2. Coulombic efficiencies (CE) also reached 94.7% after 400 cycles. This three-dimensional, ordered, macro/mesoporous structure provides a greater specific surface area, reduces local current density, and contains a lithiophilic Zn coating that serves as preferred Li nucleation sites. By combining these factors, dendrite-free Li deposition and superior electrochemical performance improvements in LMBs have been realized.

In-Plane Highly Dispersed Cu2O Nanoparticles for Seeded Lithium Deposition

Uncontrollable dendrite growth is one of the major problems that hinders the application of lithium (Li) metal anode in rechargeable Li batteries. Achieving uniform Li deposition is the key to tackle this intractable problem. Herein, we report the highly dispersed Cu₂O nanoparticles (NPs) in situ anchored on partially reduced graphene oxide via a low-temperature pyrolysis process could serve as seeds for the Li metal deposition. The lithiophilic nature of Cu₂O NPs reduces the overpotential of Li nucleation and relieves the electrode polarization, enabling uniform Li nucleation and smooth plating, thus effectively eliminating dendritic and dead Li. As a result, the resulted Li metal electrodes deliver a high Coulombic efficiency of 95.6% after 140 cycles at a current density of 2 mA cm^-2 and a prolonged lifespan (800 h at 1 mA cm^-2) for the symmetrical cell.

Fabrication of Lithiophilic Copper Foam with Interfacial Modulation toward High-Rate Lithium Metal Anodes

Although metallic lithium is regarded as an ideal anode material for high-energy-density batteries, the low cycling efficiency and safety issues hinder its practical application. In this study, a three-dimensional (3D) lithium composite anode was developed through infusing molten lithium inside the Cu foam anchored by ZnO nanoparticles. The introduced ZnO layer provides the driving force for infusion, leading to the spontaneous wetting of molten lithium. Benefiting from well-confined preloaded lithium in the Cu network, the anode displays ultralow internal resistance and stabilized interface. The fabricated anode for the symmetric cell shows extraordinarily low overpotential at high current densities (15, 33, and 50 mV at 3, 5, and 8 mA cm^-2 after 100 cycles, respectively). When paired with Li₄Ti₅O₁₂ electrode, the half-type cell demonstrates superior rate capability and long-term cycling stability after 1000 cycles at an ultrahigh rate of 10C. To the best of our knowledge, this anode shows the lowest overpotential and the highest rate capacity ever reported for 3D design anodes, confirming their great potential as lithium metal anodes.

Composite lithium metal anode by melt infusion of lithium into a 3D conducting scaffold with lithiophilic coating

Lithium metal-based battery is considered one of the best energy storage systems due to its high theoretical capacity and lowest anode potential of all. However, dendritic growth and virtually relative infinity volume change during long-term cycling often lead to severe safety hazards and catastrophic failure. Here, a stable lithium-scaffold composite electrode is developed by lithium melt infusion into a 3D porous carbon matrix with "lithiophilic" coating. Lithium is uniformly entrapped on the matrix surface and in the 3D structure. The resulting composite electrode possesses a high conductive surface area and excellent structural stability upon galvanostatic cycling. We showed stable cycling of this composite electrode with small Li plating/stripping overpotential (<90 mV) at a high current density of 3 mA/cm(2) over 80 cycles.