Metal Current Collectors Research Articles

Accommodation of Silicon in an Interconnected Copper Network for Robust Li‐Ion Storage

AbstractSilicon (Si)‐based materials are one of the most promising anodes to be applied in rechargeable lithium ion batteries. However, the active Si/electrolyte interface causes continuous side reactions and poor conductivity, which significantly decreases the cycling stability. Cu is the only metallic current collector that has been known to promote electron conduction and lithium‐ion transfer without alloying reaction occurrence. However, to the best current knowledge, scalable interface engineering incorporating Cu has not been reported. Herein, this conductive Cu interface (CCI) is constructed through a self‐assembly carbothermic reduction method to achieve efficient protection of Si/electrolyte interfaces while allowing for fast Li+ diffusion. The energy barrier of lithium‐ion diffusion through Cu is calculated to be 0.1965 eV, which is much lower than that through Au, Fe, and Ni films. Benefiting from the enhanced interfacial protection and kinetics of Si with CCI, a fading rate of only 0.068% is maintained for 1000 cycles and an aerial capacity of 4.78 mAh cm−2 is achieved after 280 cycles, which is comparable to the industry standards required for practical application.

Flexible and transparent planar supercapacitor based on embedded metallic mesh current collector

The preparation of planar transparent flexible supercapacitors with high energy storage capacity, high mechanical properties and excellent optical properties is still a great challenge. The typical planar supercapacitor electrodes adopting the interdigital structure are semi-transparent, for the interdigital parts are opaque. Herein, we report a highly transparent and flexible planar supercapacitor by utilizing the embedded metallic mesh as the current collectors. The embedded metallic mesh with an interdigital structure, which was fabricated though the selective electrodeposition and film-invertion techniques, was employed as the planar supercapacitor electrode after being loaded with MnO2 by electrochemical deposition. The realized planar solid-state supercapacitor exhibits high performance electrochemical characters and high transparency with an areal capacitance of 1.33 mF cm−2 and an optical transmittance of 81.7%. Further, the planar solid-state supercapacitor offered superior cycling stability of 99.3% retention even after 10 000 cycles, and meanwhile showed good mechanical stability, maintaining the areal capacitance of 90.3% retention after 1000 bending times at a radius of 5 mm, which mainly attribute to the embedded nature of the interdigital current collector. With excellent transparency, flexibility, and capacitance properties, the planar supercapacitor shows great potential in portable and comfortable designs for transparent wearable electronic device.

Transformation of oxide ceramic textiles from insulation to conduction at room temperature.

Oxide ceramics are considered to be nonconductive brittle materials, which limits their applications in emerging fields such as conductive textiles. Here, we show a facile domino-cascade reduction method that enables rapid transformation of ceramic nanofiber textiles from insulation to conduction at room temperature. After putting dimethylacetamide-wetted textiles, including TiO2, SnO2, BaTiO3, and Li0.33La0.56TiO3, on lithium plates, the self-driven chemical reactions induce defects in oxides. These defects initiate an interfacial insulation-to-conductive phase transition, which triggers the domino-cascade reduction from the interface to the whole textile. Correspondingly, the conductivity of the textile sharply increased from 0 to 40 S/m over a period of 1 min. The modified oxide textiles exhibit enhanced electrochemical performance when substituting the metallic current collectors of lithium batteries. This room temperature reduction method can protect the nanostructures while inducing defects in oxide ceramic textiles, appealing for numerous applications.

MoO3/CNTs Loading in Separator for Performance-Improving Current-Collector-Free Lithium Ion Batteries

A novel strategy for structural design of current-collector-free lithium ion batteries (LIBs) has been proposed, MoO3/CNTs loading on the single side of a separator by a simple spin-coating method. LIBs with such a MoO3-based composite separator eliminate the need for metal current collectors and exhibit an extra high specific capacity (0.2C, ∼1200 mA h g–1). Faster ion transport and lower charge transfer resistance (Rct) of the composite separator were proved compared with the traditional MoO3-based electrode, which results in the increased special capacity. In addition, the pseudocapacitive effect caused by vacancies and narrow interval in the MoO3/CNTs materials also contributes to the high specific capacity of the batteries. The highly efficient ion and electron transport ability of the composite separator were proved in this study, and such a novel design strategy would be an alternative for low-cost LIBs.

Damage-tolerant, laminated structural supercapacitor composites enabled by integration of carbon nanotube fibres

A natural embodiment for multifunctional materials combining energy-storing capabilities and structural mechanical properties are layered structures, similar to both laminate structural composites and electrochemical energy-storage devices. A structural composite with integrated electric double layer capacitive storage is produced by resin infusion of a lay up including woven glass fabric used as mechanical reinforcement, carbon nanotube non-woven fabrics as electrodes/current collectors and a polymer electrolyte. The energy-storing layer is patterned with holes, which after integration form resin plugs for mechanical interconnection between layers, similar to rivets. Finite element modelling is used to optimise rivet shape and areal density on interlaminar shear properties. Galvanostatic charge-discharge tests during three-point bending show no degradation of properties after large deflections or repeated load/unload cycling at 3.5 V. This mechanical tolerance is a consequence of the elimination of metallic current collectors and the effective integration of multifunctional materials, as observed by electron microscopy and x-ray computed tomography. In contrast, control samples with metallic current collectors, analogous to embedded devices, rapidly degrade upon repeated bending.

Micro-patterned metal current collectors for high aspect ratio flexible graphene supercapacitors

When graphene thin films are used as high aspect ratio supercapacitor electrodes, their performance can be limited due to graphene’s relatively low electrical conductivity, compared with metals. The integration of the graphene film with a metal current collector can overcome this limited conductivity. However, poor adhesion between pristine graphene and metal films adversely affects a supercapacitor’s flexibility. In this study, a metal current collector film was patterned on a flexible substrate in the form of a microgrid, via selective laser sintering of silver nanoparticles. The delamination of the graphene film was mitigated by interlocking it with the substrate using laser transmission welding. A specific capacitance of 5.8 mF/cm2 was obtained at 1.5 mA/cm2 with PVA- H3PO4 electrolyte, and the capacitance was retained at up to 94% when the electrode length was increased by six times. In addition, a thin gold (Au) layer was electrodeposited to the silver grid to improve its electrochemical stability. As a result, the capacitance change remained below 10% for 10,000 charging/discharging cycles. The electrodeposition of pseudocapacitive manganese dioxide (MnO2) nanoparticles was also performed, further increasing the capacitance to 49.1 mF/cm2 at 1 mA/cm2 with 0.5 M Na2SO4 electrolyte.

Modeling the Performance of A Flow-Through Gas Diffusion Electrode for Electrochemical Reduction of CO or CO2

A flow-through gas diffusion electrode (GDE) consisting of agglomerate catalysts for CO or CO2 reduction, gas channels for reactants, aqueous electrolytes for ionic transport, and metallic current collectors was simulated and evaluated using a numerical model. The geometric partial current densities and Faradaic Efficiencies (FE) for CH4, C2H4 and H2 generation in GDEs were calculated and compared to the behavior of analogous aqueous-based planar electrodes. The pH-dependent kinetics for CH4 and C2H4 generation were used to represent the intrinsic catalytic characteristics for the agglomerate catalyst. The modeling indicated that relative to planar electrodes for either CO reduction (COR) or CO2 reduction (CO2R), substantial increases in electrochemical reduction rates and Faradaic efficiencies are expected when flow-through GDEs are used. The spatially resolved pH and reaction rates within the flow-through GDEs were also simulated for two different operating pHs, and the resulting transport losses were analyzed quantitatively. For CO2 reduction, substantial loss of CO2 via chemical reaction with the locally alkaline electrolyte was observed due to the increased pH in operating GDEs.

Flexible and high-energy-density Zn/MnO2 batteries enabled by electrochemically exfoliated graphene nanosheets

Electrochemically exfoliated graphene nanosheets were proposed for flexible and high-performance Zn–MnO2 batteries without polymer binder and metal current collectors.

Regulating lithium nucleation and growth by zinc modified current collectors

Lithium metal is commonly regarded as the “Holy Grail” anode material for high energy density rechargeable batteries. However, the uncontrollable growth of Li dendrites has posed safety concerns and thus greatly hindered its large-scale application. Here we have modified the surface of a commercial anode current collector, Cu foil, with a thin layer of Zn by a facile electroplating method, in order to regulate the Li nucleation and the following growth processes. Because of the formation of a solid solution buffer layer and Li-Zn alloy phases, the Li nucleation overpotential was dramatically reduced, realizing a uniform Li nucleation and a smooth Li plating morphology. As a result, significantly improved long-term cycling performance with a high Coulombic efficiency was achieved by the lithiophilic Zn coated Cu foil as a current collector. Full cells of Li–LiFePO4 and Li–S using the Li deposited on the Zn modified Cu as the anode, showed increased capacity with low voltage hysteresis and greatly enhanced cycling stability, ascribed to the uniform Li deposition and formation of a stable SEI layer. This work demonstrates the feasibility of employing lithiophilic modified Cu foils as Li metal current collectors for practical applications.

Computational Screening of Current Collectors for Enabling Anode-Free Lithium Metal Batteries

Lithium metal cells are key towards achieving high specific energy and energy density for electrification of transportation and aviation. Anode-free cells are the limiting case of lithium metal cells involving no excess lithium and the highest possible specific energy. In addition, anode-free cells are easier, cheaper and safer as they avoid handling and manufacturing of lithium metal foils. Issues related to dendrite growth and poor cycling are magnified in anode-free cells due to lack of excess lithium. Electrolyte and current collector surface play a crucial role in affecting the cycling performance of anode-free cells. In this work, we have computationally screened for candidate current collectors that can nucleate lithium effectively and allow uniform growth. These are determined by the free energy of lithium adsorption and lithium surface diffusion barrier on candidate current collectors. Using density functional theory calculations, we show that Li-alloys possess ideal characteristics for Li nucleation and growth. These can lead to vastly improved specific energy compared to current transition metal current collectors.

Bio-inspired interfaces for easy-to-recycle lithium-ion batteries

The recycling of spent lithium-ion batteries has significant potential to benefit our society economically and environmentally as well as preserving raw materials. Although diverse process chains have been applied or under development to recycle batteries, a common, critical issue for battery recycling is the separation of the metallic current collector from the composite film of the electrode. In this study, inspired by the amazing controllable attachment and detachment ability of geckos’ foot-hairs, microscale near-surface architecture is designed on the interface between the current collector and the composite film in lithium-ion batteries, so that it displays controllable and directional adhesion, i.e., enhanced adhesion can be obtained during its lifetime to cope with the substantial volume changes of the composite film upon intercalation and deintercalation, whereas during recycling, the composite layer of the electrode can be easily peeled off from the current collector in a certain direction. This study is the first application of structural adhesives for the development of easy-to-recycle lithium-ion batteries. This technology can also be extended to other electronic products to avoid an ever-growing volume of electronic waste. The fundamental understanding on the interfacial adhesion and delamination mechanisms provides a scientific footing for the realization of next-generation easy-to-recycle electronics.

Fluoride-Ion Batteries: On the Electrochemical Stability of Nanocrystalline La0.9Ba0.1F2.9 against Metal Electrodes

Over the past years, ceramic fluorine ion conductors with high ionic conductivity have stepped into the limelight of materials research, as they may act as solid-state electrolytes in fluorine-ion batteries (FIBs). A factor of utmost importance, which has been left aside so far, is the electrochemical stability of these conductors with respect to both the voltage window and the active materials used. The compatibility with different current collector materials is important as well. In the course of this study, tysonite-type LaBaF, which is one of the most important electrolyte in first-generation FIBs, was chosen as model substance to study its electrochemical stability against a series of metal electrodes viz. Pt, Au, Ni, Cu and Ag. To test anodic or cathodic degradation processes we carried out cyclic voltammetry (CV) measurements using a two-electrode set-up. We covered a voltage window ranging from −1 to 4 V, which is typical for FIBs, and investigated the change of the response of the CVs as a function of scan rate (2 mV/s to 0.1 V/s). It turned out that Cu is unstable in combination with LaBaF, even before voltage was applied. The cells with Au and Pt electrodes show reactions during the CV scans; in the case of Au the irreversible changes seen in CV are accompanied by a change in color of the electrode as investigated by light microscopy. Ag and Ni electrodes seem to suffer from contact issues which, most likely, also originate from side reactions with the electrode material. The experiments show that the choice of current collectors in future FIBs will become an important topic if we are to develop long-lasting FIBs. Most likely, protecting layers between the composite electrode material and the metal current collector have to be developed to prevent any interdiffusion or electrochemical degradation processes.

Electrochemical reduction of hematite-based ceramics in alkaline medium: Challenges in electrode design

Electrochemical reduction of low-conductive hematite-based ceramics represents a novel approach for iron recovery and waste valorisation. The process itself allows a flexible switching between hydrogen generation and iron reduction, important for the intermittent renewable-energy-powered electrolytic process. The present study focuses on the direct electrochemical reduction of aluminium-containing hematite in strong alkaline media. Within this scope, the reduction mechanisms of porous and dense cathodes, with 60%, 37% and 3% of open porosity, were investigated using different types of electrodes configuration: nickel-foil and Ag-modified nickel-foil supported configuration (cathodes facing or against the counter electrode), and nickel-mesh supported configuration. The efficiency of the iron reduction was compared for different electrode concepts. The results highlight the importance of electrolyte access to the interface between the metallic current collector and ceramic cathode for attaining reasonable electroreduction currents. Both excessively porous and dense ceramic cathodes are hardly suitable for such reduction process, showing a necessity to find a compromise between mechanical strength of the electrode and its open porosity, essential for the electrolyte access.

Bioinspired Interfacial Strengthening Flexible Supercapacitors via Hierarchically Topological Interlocking Strategy.

Flexible micro-supercapacitors (MSCs) featured with high storage capacity and mechanical stability are essential and indispensable for the development of wearable devices. Since the active materials physically deposited on the current collectors are rigid and will be desquamated under the mechanical cycling, the performance of flexible MSCs is still limited by the weak interfacial adhesions between materials and collectors. The effective strategy to strengthen the interfacial adhesion is one important key to achieve high-performance flexible MSCs. In this work, a flexible symmetrical micro-supercapacitor with a bioinspired hierarchically topological interlocking interfacial enhancement strategy was presented. Based on the high stability metal current collectors on the polyimide substrate, two-level 3D interlocking structures between the active materials and the current collectors were further utilized, which was inspired by the structures of a gecko's feet and a tree's roots in rock cracks, respectively. Through these 3D interlocking structures, the effective contact areas and the adhesion strengths of two interfaces, that is, the active material/current collectors and the current collector/substrate interfaces, are significantly enhanced. The energy density of the interfacial enhanced active carbon symmetrical MSC (IE SMSC) has been improved over 3 times in comparison with the in-plane active carbon SMSC (SMSC). The capacitance of IE SMSC can remain 92.9% even after 5000 cycles of bending treatment. Even more remarkable, the potential window of the IE SMSC can expand to 1.6 V in the aqueous electrolyte. The results show that the hierarchically topological interlocking strategy can not only ensure the mechanical stability of the flexible MSC but also improve its energy efficiency. Our strategy provides a new perspective for the study of flexible supercapacitors and various flexible devices to achieve high adhesion, high flexibility, and high electrical capacitive performance.

Thick electrodes upon biomass-derivative carbon current collectors: High-areal capacity positive electrodes for aluminum-ion batteries

Rechargeable aluminum-ion batteries (AIBs) are considered as low-cost safe energy storage devices beyond lithium-ion batteries, due to the high volumetric capacity and rich abundance of aluminum. However, the highly corrosive room temperature ionic liquid electrolyte causes serious problems in the traditional metal current collectors, and electrochemical inert metals with higher density have been commonly used, which leads to dramatic decreased material utilization in the positive electrode. For addressing such issues, here a biomass-derivative carbon (BDC) current collector is demonstrated to construct millimeter-scale thick positive electrodes based on two types of graphite active materials (with different planar sizes) and two electrode configurations. The results suggest the strategy of using single-side casting process with graphite of smaller planar size would be more promising to promote the overall electrochemical properties and energy storage performance. The as-assembled thick electrode (with thickness up to ∼2 mm) using the same type of graphite is able to deliver much enlarged areal loading (36 mg cm−2), showing greater areal capacity for energy storage. The strategy and mechanism in this work offers a considerable approach for improving the current collectors and promoting the graphite proportion in AIBs.

1D Buliding Block Strategies for High Energy Density Li-Ion Batteries

Ever-increasing demand for high-performance portable electronics, electric vehicles (EVs) and grid-scale energy storage systems (ESSs) has been in relentless pursuit of advanced energy storage systems with reliable electrochemical properties. Among a vast variety of rechargeable power sources, undoubtedly, lithium-ion batteries have been most widespread and still garnered considerable attention due to their well-customized battery characteristics. From the electrode architecture point of view, most conventional electrodes are characterized with simple and random pile-up of electrode active materials, carbon powder conductive additives and polymer binders on top of metallic foil current collectors. Unfortunately, such a stereotyped electrode architecture often gives rise to non-uniform and sluggish electron/ion transport particularly in their through-thickness direction and is also vulnerable to structural disruption upon mechanical deformation. In particular, the poorly-developed electron/ion conduction pathways of the electrodes eventually provoke unwanted electrochemical polarization, which becomes more serious at harsh operating conditions such as high-mass loading electrodes and fast charge/discharge current densities that are urgently needed for high-energy EV batteries. Due to these unavoidable limitations, the conventional electrode architecture has posed a formidable challenge to sustainable progress of battery performance, thus pushing us to search for alternative solutions. Here, we demonstrate a new class of all-nanomat lithium-ion batteries (LIBs) based on one-dimensional (1D) building elements interweaved into heteronanomat skeletons. Among various electrode materials, silicon (Si), over-lithiated layered oxide (OLO) materials and redox-active organic materials are chosen as model systems to explore the feasibility of this new cell architecture and achieve unprecedented cell capacity. Nanomat electrodes, which are completely different from conventional slurry-cast electrodes, are fabricated through concurrent electrospinning (for polymeric nanofibers) and electrospraying (for electrode materials/carbon nanotubes (CNTs)). Electrode active material powders are compactly embedded in the spatially interweaved polymeric nanofiber/CNT heteromat skeletons, which play a crucial role in constructing three-dimensional (3D)-bicontinuous ion/electron transport pathways and in removing metallic foil current collectors. Driven by the aforementioned structural/chemical uniqueness, the all-nanomat electrodes show exceptional improvement in electrochemical performance as well as mechanical deformability, which lie far beyond the values achievable with conventional LIB technologies.

(Invited) Tuning Electrochemical Performance of Lithium-Ion Cells By Introducing Laser-Generated Electrode Architectures

Laser technology in lithium-ion battery (LIB) manufacturing could enable rapid manufacturing, high reliability, and a reduction of production costs. Laser cutting and welding processes for batteries already reached a high industrial readiness level. A new approach which is assigned to laser micro-structuring of battery materials has a huge impact on battery performance and operational lifetime of lithium-ion cells and an up-scaling for industrial production is currently investigated. So far, different types of laser structuring were used on metallic current collectors, separators, and thin or thick film composite electrodes. For thin metallic current collector foils, at anode and cathode sides, self-organized structuring by laser-induced periodical surface structures were successfully applied for improving electrode film adhesion. Direct laser ablation was applied for the generation of capillary structures, which was found to be most powerful in order to transform electrode and separator surfaces to superwicking. Thick film composite electrodes in lithium-ion cells are complex multi-material systems with defined material components, grain sizes, porosities, and pore size distributions in the micrometer and sub-micron range. The development of laser generated electrode architectures became a promising approach to overcome limitations in lithium-ion diffusion kinetics, high inter-electrode ohmic resistances, and mechanical stresses due to high volume changes during battery operation. It was shown, that structure sizes down to 10-30 µm and high aspect ratios enable advanced electrode architectures with huge benefits regarding capacity retention and cell life-time for high power operations during charging/discharging. For laser structured electrodes, the overall impedance was reduced and the diffusion kinetics could be enhanced which was proven by galvanostatic intermittent titration technique, cyclic voltammetry, and electrochemical impedance spectroscopy. Furthermore, the new electrode architecture provides new lithium-ion diffusion pathways, which could be indirectly proven by post-mortem analysis of entire electrodes by laser-induced breakdown spectroscopy (LIBS). It is evident that the increased active surface area provided by laser generated electrode architectures act as an attractor for lithium-ions which finally is responsible for the boost in battery performances. By increasing the cathode film thickness to values significantly larger than 150 μm an increase of the specific capacity or energy density at cell level was achieved. While the energy per area increases with the cathode layer thickness, the power density will in general decrease due to an increasing diffusion overpotential. In addition, the mechanical integrity of the films will decrease with increasing layer thickness and the migration of binders to the electrode surface will occur through altered drying conditions. The mechanical degradation of the cells due to the volume change inherent in the battery process in the electrodes will become more important as the layer thickness increases. Laser structuring of the electrodes can counteract these processes and will also improve the high current capability. Finally, LIBs with high-energy and high-power density can be realized by introducing laser generated electrode architectures (3D battery concept), i.e., at the same time, improved electrolyte transfer in thick film electrodes and improved lithium ion transport kinetics are achieved. For developing next generation batteries including the 3D battery concept for large footprint areas, high energy materials such as nickel-enriched Lithium-Nickel-Manganese-Cobalt-Oxide (NMC) for cathodes and silicon-based anodes are introduced.

(Invited) Electrophoretic Deposition of Energy Storage Metal Oxides

Electrodeposition is an attractive tool for synthesizing energy storage materials - such as transition metal oxides (TMOs) - for batteries and capacitors. A key advantage of electrodeposition is that the material of interest is synthesized directly on a metal or carbon current collector promoting an intimate, low resistance contact between the deposited material and the current collector. But electrodeposition methods have limited reach if a soluble form of the metal ion does not exist. LixNb2O5 is one technologically important TMO that falls into this category. The electrophoretic deposition (EPD) process we have developed produces nanoporous, phase pure T-Nb2O5 films 38 nm to 144 nm in thickness. These films exhibit unusually high specific capacities, Csp (units: mAh/g). For example, films of 60 nm thickness produce Csp = 420 mAh/g at 5 A/g and 220 mAh/g at 50 A/g which is to be compared with a theoretical Faradaic capacity of 202 mAh/g. T-Nb2O5 films also produce impressive energy and power with specific energy from 770 - 486 Wh/kg, and specific power in the range from 9-90 kW/kg. It is important to add here that the accuracy of all of these mass-normalized metrics is insured by directly measuring the mass of these films using quartz crystal microbalance (QCM) gravimetry. Our investigation of T-Nb2O5 is still in its early stages, but the exceptional performance seen for these EPD T-Nb2O5 films is very encouraging. Our hypothesis is that EPD provides a general method for the synthesis of energy storage materials with signicant advantages relative to competing methods, including the ability to impart a controllable porosity and the ability to facilitate the enhancement of mechanical and electrical properties via compositing. In this presentation, I will discuss this EPD process and our recent investigations of the mechanisms of degradation operating in the T-Nb2O5 films prepared using this process. Gold@T-Nb2O5 core@shall nanowires can also be obtained by EPD and the properties of these systems for electrical energy storage will be compared with those of T-Nb2O5 films. Finally, the lithiation/potential-dependent electrical conductivity of solid (non core-shell) T-Nb2O5 nanowires prepared by has been measured for the first time, in-situ. These data, showing variations in electrical conductivity by three orders of magnitude with lithiation state, will also be discussed.

A Route to High-Toughness Battery Electrodes

There is increasing interest in materials that combine energy-storing functions with augmented mechanical properties, ranging from flexibility in bending to stretchability to structural properties. In the case of lithium-ion batteries, these mechanical functions could enable their integration in emerging technologies such as wearable, free-form electronics and ultimately as structural elements, for example, in transport applications. This work presents a method to produce flexible LiFePO4 LFP electrodes with an extraordinary combination of electrochemical and mechanical performance. Such electrodes exhibit an exceptionally high specific toughness, combined with superior rate capability and energy density, with respect to reference electrodes with typical metallic current collectors. These properties are a result of the strong adhesion of the active material particles to the high surface area carbon nanotube fiber fabric, used as a lightweight, tough, and highly conducting current collector. This strong adherence minimizes electrical resistance, mitigates interfacial failure, and increases ductility through heterogeneous strain after cohesive failure of the inorganic phase. As a result, these electrodes can withstand large deformations before fracture, and, even after fracture, they retain excellent electrochemical performance, approximately double that of unstretched, Al-supported LFP electrodes with equivalent loading.

A stable artificial protective layer for high capacity dendrite-free lithium metal anode

The metallic lithium (Li) is considered as the most promising anode material for high-energy batteries. Nevertheless, the uncontrollable growth of Li dendrite and unstable electrolyte/electrode interface still hinder the development of Li-based battery. In this work, a novel strategy has been proposed to stabilize Li anode by in-situ polymerizing polypyrrole (PPy) layer on Ni foam (PPy@Ni foam) as an artificial protective layer. The PPy protective layer can effectively decrease the contact between Li metal and electrolyte during cycling. In addition, the morphology characterization shows that the PPy layer can help the even Li deposition underneath the layer, leading to a dendrite-free Li anode. As a result, when deposited 2 mAh•cm−2 Li metal, the PPy@Ni foam can keep stable Coulombic efficiency (99%) during nearly 250 cycles, much better than the pure Ni foam (100 cycles). Even in the case of the Li capacity of 10 mAh•cm−2, the stable cycling performance for 60 cycles can still be achieved. Furthermore, when assembled with LiFePO4 material as the cathode for a full cell, the PPy@Ni foam can keep high capacity retention of 85.5% at 500 cycles. In our work, we provide a simple and effective method to enhance the electrochemical performances of Li metal-based batteries, and reveal a new avenue to design three-dimensional (3D) metallic current collector for protecting the Li metal anode.