Anode-free Lithium Metal Batteries Research Articles

Regulation of Extra Li Inventory in Anode-Free Lithium Metal Batteries by Li-Rich Layered Oxide Cathode Materials.

Li-rich layered oxide (LRO) cathode material is utilized in anode-free Li metal batteries to provide extra Li inventory, compensating for the constant Li loss during cycling. The Li compensation mechanism of LRO in the anode-free system is elucidated by exploring the reversible/irreversible Li consumption behaviors. Moreover, the relationship between cathode areal capacity, Li inventory, and the cycling performance of the Cu||LRO cell is quantitatively analyzed. The well-designed Cu||LRO anode-free cell demonstrates 51% capacity retention after 60 cycles at a practical areal capacity of 5.0 mAh cm-2, overwhelming the 0.6% capacity retention for Cu||NCM523. Further optimization with an artificial anode protection layer and a fully fluorinated electrolyte enhances the capacity retention of Cu||LRO to 61.4% and 71.5% after 60 cycles, respectively. Combining its low initial Coulombic efficiency and high specific energy, the LRO cathode shows great prospects in the future development of high energy and long lifespan anode-free Li metal batteries.

Revealing the Principles of Confining Electroplated Lithium beneath the CVD Grown Single Layer 2D Materials.

Owing to the nanoscale thickness, excellent mechanical and chemical stabilities, 2D materials including graphene and hexagonal boron nitride have emerged as promising artificial solid electrolyte interphase (SEI) candidates for lithium metal batteries. However, whether the implementation of 2D materials is beneficial to electrochemical performance remains controversial, and the key to confining the electroplated Li beneath the 2D materials remains elusive. Here, a nanocrystalline graphene (NG) film is synthesized on high-carbon Cu and the Li plating/stripping behavior on Cu grown with different 2D materials is investigated. Interestingly, in contrast to the commonly obtained Li particles on other substrates during nucleation, a smooth Li layer is obtained on NG/Cu, leading to a compact Li layer with more stable electrochemical performance. The finite element method simulations validate that the low electrical conductivity and the high density of defects on NG film drive the fast entry of electrolytes into the NG/Cu interface and promote homogenous Li nucleation. This work reveals the principles of confining electroplated Li beneath the 2D materials, and paves the way for the applications of 2D materials in artificial SEIs and anode-free lithium metal batteries.

Sub‐Nano Confinement Engineering Toward Anion‐Reinforced Solvation Structure to Achieve Highly Reversible Anode‐Free Lithium Metal Batteries

AbstractThe practical application of anode‐free lithium metal batteries (AFLMBs) is impeded by poor cycling performance due to sluggish Li+ transport kinetics, unfavorable side reactions, and dendrite Li growth. To address these issues, ≈200 nm zeolitic imidazolate framework‐8 (ZIF‐8) interphase layer is introduced to enable highly reversible Li plating/stripping by electrosynthesis method. ZIF‐8 interphase layer with sub‐nano windows accelerates Li+ desolvation kinetics and thus suppresses unfavorable side reactions. Further, the internal cavities of ZIF‐8 serve as an anion reservoir to modulate anion‐reinforced solvation structure of Li+, facilitating the formation of LiF‐ and Li3N‐riched solid–electrolyte interphase. Thus, the Li/Cu@ZIF‐8 asymmetric cell exhibits remarkable Aurbach coulombic efficiency of 99.84%, and Cu@ZIF‐8/LiFePO4 AFLMB delivers impressive capacity retention (57.8%) over 400 cycles. This work highlights the effectiveness of ZIF‐8 to enable highly reversible AFLMBs and inspires the potential application of porous materials with sub‐nano windows and interval cavities in anode‐free batteries.

Highly Reversible Anode-Free Lithium Metal Batteries Enabled by Porous Organic Cages with Subnano Lithiophilic Triangular Windows.

The widespread application of anode-free lithium metal batteries (AFLMBs) is hindered by the severe dendrite growth and side reactions due to the poor reversibility of Li plating/stripping. Herein, our study introduces an ultrathin interphase layer of covalent cage 3 (CC3) for highly reversible AFLMBs. The subnano triangular windows in CC3 serve as a Li+ sieve to accelerate Li+ desolvation and transport kinetics, inhibit electrolyte decomposition, and form LiF- and Li3N-rich solid-electrolyte interphases. Moreover, the lithiophilic backbone of CC3 homogenizes Li+ distribution and deposition with mitigated dendrite growth. Thus, CC3 promotes Li plating/stripping kinetics and reversibility, achieving an ultralong stability over 8000 h of the Cu@CC3 electrode. Furthermore, practical Cu@CC3/LiFePO4 AFLMBs deliver a capacity retention (66%) over 600 cycles. This work emphasizes the effectiveness of CC3 to regulate the Li plating/stripping behavior, demonstrating the application potential of porous organic cages for enhancing the cycle life of AFLMBs.

N, S-Rich SEI Derived From Continuously-Releasing Additive for Anode-Free Lithium-Metal Batteries in Commercial Carbonate Electrolyte.

Featured with the highest possible energy density, anode-free lithium-metal batteries (AFBs) are still challenged by the fast capacity decay, especially for the ones operated in commercial carbonate electrolytes, which can be ascribed to the poor stability and continual broken/formation of the solid-electrolyte interface (SEI) formed on the anode side. Here, sacrificial additives, which have low solubility in carbonate electrolytes and can be continuously released, are proposed for AFBs. The sacrificial and continuously-releasing feature gifts the additives the capability to form and heal the SEI during the long-term cycling process, thus minimizing the loss of active Li and enabling the AFLMBs with high loading LiNi0.8Co0.1Mn0.1O2 (21.7mg cm-2) cathode a high capacity-retention of 68.9% after 50 cycles in commercial carbonate electrolyte, in contrast to the control cell failed after 30 cycles. This work presents a simple and potential strategy for the practical applications of AFLMBs.

Probing the Influence of Steric Hindrance in Nonfluorinated Ether Electrolytes for Lithium Metal Batteries

Abstract Lithium metal batteries (LMBs), especially anode free LMBs, promise much higher energy density than current lithium-ion batteries but suffer from poor capacity retention. While novel electrolytes have been designed to extend cycle life in anode free LMBs, most of them contain a high fraction of fluorinated solvents or diluents that can cause environmental concerns. Herein, we report the design and synthesis of a group of nonfluorinated ether solvents (termed xME solvents). By substituting the methyl terminal group of 1,2-dimethoxy ethane (DME) with different alkyl groups, the solvation power of xME solvents was tuned to be weaker, leading to more ion pairing in electrolyte solvation structure. In anode free type Cu/LiFePO4 (Cu/LFP) cells, xME electrolytes in general show better capacity retention than DME electrolyte. Some xME electrolytes also show better oxidative stability than DME against aluminum and LiNi0.1Mn0.1Co0.8O2 (NMC811) electrodes. While the general improvement in LMB cycle life and oxidative stability can be attributed to more ion pairing, the local variation within xME electrolytes indicates other factors are also important. Our work proposes a molecular design strategy to fine-tune ion solvation structure of nonfluorinated ether electrolytes for LMBs.

Using X-ray Microscopy to Probe Failure Mechanisms in Anode-free Cells: An Industry Perspective

To meet the energy demands of future electric vehicle technologies, batteries with ever-increasing energy densities are desired. One promising technology is an anode-free lithium metal battery (AFLMB) cell, where lithium ions are deposited directly on the anode current collector, resulting in more energy dense cells relative to the current state-of-the-art lithium-ion battery cell. Nevertheless, anode-free cells are prone to early capacity degradation and cell failure. To better understand the degradation mechanisms in these devices, we present a methodology for assessing microstructural changes in battery cells that can be easily implemented within existing battery manufacturing facilities. We employed X-ray tomographic imaging and analyses on small format, AFLMB pouch cells. Anode thickness variations were characterized non-destructively by housing the pouch cells in fabricated pressurized jigs during both cycling and tomographic imaging. Additionally, we present a technique to measure cathode porosities and tortuosities at the end-of-life (EOL) with higher resolution X-ray imaging. The proposed methodology is able to accurately reproduce known microstructural behaviors in AFLMBs. At the anode, significant thickness changes are observed because of continuous electrolyte degradation and solid electrolyte interphase growth. At the cathode, large porosity changes are detected at the EOL, potentially owing to NCM (LiNixCoyMnzO2) particle cracking.

Multifunctional Layer Coated Cu for Anode-Free Lithium Metal Batteries

Anode free lithium metal battery (AFLMB) is one of the alternate choices and new system for high energy density storage system because it has no active anode material initially. In addition, the fabrication of AFLMB is simple, low-cost, safe since Li metal or other active anode material is not directly used as an anode. The energy density of AFLMB will be significantly larger, by more than ~50% relative to conventional LIBs. Since the Li amount is limited and electrolyte decomposition, consuming Li during the SEI formation, the capacity can fade quickly relative to LMB. However, AFLMB is not only provide the highest energy density but the best system to understand the interfacial phenomena [1-3] and the effectiveness of the approaches to improve cell performances of LMBs [4-8]. In this talk, I will present our multifunctional layer coating approaches to improve the cell performance of anode-free lithium metal batteries. Keywords: Multifunctional Layer Coating; Anode-free; Lithium; Coulombic efficiency; Capacity Retention

Interrelation between External Pressure, SEI Structure and Electrodeposit Morphology in an Anode-Free Lithium Metal Battery

We explore the interrelation between external pressure (0.1, 1, 10 MPa), solid electrolyte interphase (SEI) structure/morphology, and lithium metal plating/stripping behavior. To simulate anode-free lithium metal batteries (AF-LMBs) analysis was performed on “empty” Cu current collectors in standard carbonate electrolyte. Lower pressure promotes organic-rich SEI and macroscopically heterogeneous, filament-like Li electrodeposits interspersed with pores. Higher pressure promotes inorganic F-rich SEI with more uniform and denser Li film. A “seeding layer” of lithiated pristine graphene (pG@Cu) favors an anion-derived F-rich SEI and promotes uniform metal electrodeposition, enabling extended electrochemical stability at a lower pressure. State-of-the-art electrochemical performance is achieved at 1MPa: pG-enabled half-cell is stable after 300 hrs (50 cycles) at 1 mA cm-2 rate - 3 mAh cm-2 capacity (17.5 mm plated/stripped), with cycling Coulombic efficiency (CE) of 99.8%. AF-LMB cells with high mass loading NMC622 cathode (21 mg cm-2) undergo 200 cycles with a CE of 99.4% at C/5-charge and C/2-discharge (1C = 178 mAh/g). Density functional theory (DFT) highlights the differences in the adsorption energy of solvated-Li+ onto various crystal planes of Cu (100), (110), and (111), versus lithiated/delithiated (0001) graphene, giving insight regarding the role of support surface energetics in promoting SEI heterogeneity.

CNT/GO Zinc Composite as Dual-Functional Electroconductive and Lithophilic Coatings for Cu-Current Collectors in Anode-Free Li Batteries

The novel concept of anode-free lithium batteries (AFLBs), which eliminate excess lithium while preserving numerous advantages, presents certain challenges such as notable capacity loss, low electronic conductivity, and reduced coulombic efficiency. To address these issues, modified lithiophilic current collectors are essential for enhancing electrochemical performance. This study focuses on surface modification of the copper current collector through carbonaceous zinc composites co-electrodeposition benefiting lithiophilicity and electroconductivity [1]. These composites, including 1D Zn/Carbon Nanotubes (CNT-Zn) and 2D Zn/Graphene Oxide (GO-Zn), are coated on the copper current collector, varying their compositions to create a lithiophilic thin layer and improve electroconductivity [2-3]. The aim of this modification is to promote smoother plating and stripping processes, thereby facilitating uniform lithium deposition without dendrite formation. The composite-modified current collector demonstrated improved cyclability over 200 cycles at 0.393 mA, reduced overpotential at various applied current densities (ranging from 0.392 to 1.962 mA cm-2), and provided uniform lithium deposition. Electrochemical Impedance Spectroscopy (EIS) revealed the most reduced charge transfer resistance (Rct) of 38.4 Ω for Zn/Graphene Oxide (GO-Zn) after the first cycle. It also indicated that a higher amount of CNT and GO leads to worse electrochemical performance due to the agglomeration of carbonaceous particles on the substrate.References Pooria Afzali, Eugenio Gibertini, Luca Magagnin, Improved plating/stripping in anode-free lithium metal batteries through electrodeposition of lithiophilic zinc thin films,, Electrochimica Acta, Volume 488,2024,144190, ISSN 0013-4686, https://doi.org/10.1016/j.electacta.2024.144190.Ge J, Hong J, Liu T, Wang Y. Rational design of a self-supporting skeleton decorated with dual lithiophilic Sn-containing and Ndoped carbon tubes for dendrite-free lithium metal anodes. J Mater Chem A 2022;10:11458-69.Mehmet Oguz Guler, Tugrul Cetinkaya, Ubeyd Tocoglu, Hatem Akbulut, Electrochemical performance of MWCNT reinforced ZnO anodes for Li-ion batteries, Microelectronic Engineering, Volume 118, 2014, Pages 54-60, ISSN 0167-9317, https://doi.org/10.1016/j.mee.2013.12.029

The Mechanical Dynamics of Lithium-Metal Battery Formation Protocols

Formation, the first charge of an SEI forming battery system, is well understood to affect the cycling behavior of the system. This is particularly crucial for anode-free lithium metal batteries due to the significant effect of initial Li plating morphology and SEI on subsequent plating and, therefore, long-term cyclability. Low-cost, operando tools that spatially map heterogeneities are important for the study and validation of formation protocols. Here, we use spatially-resolved ultrasound transmission during formation to study variations in gas formation and morphology of Li metal anode-free cells as a function of temperature, pressure, and current density. These non-invasive results are validated with ex situ optical and SEM imaging, and XPS is used to determine the SEI speciation. We then cycled these formed cells at increased rates while measuring the systems with one-dimensional acoustics to correlate formation with mechanical and electrochemical cycling performance.

Ionic Liquid Additive Mitigating Lithium Loss and Aluminum Corrosion for High-Voltage Anode-Free Lithium Metal Batteries.

Concentrated electrolytes based on lithium bis(fluorosulfonyl)imide (LiFSI) have been proposed as an effective Li-compatible electrolyte for anode-free lithium metal batteries (AFLMBs). However, these electrolytes suffer from severe aluminum corrosion at an elevated potential. To address this issue, we propose a binary ionic liquid (IL) electrolyte additive comprising the 1-methyl-1-butyl pyrrolidinium cation (Pyr14+), difluoro(oxalate)borate anion (DFOB-), and difluorophosphate (PO2F2-) anion to mitigate the Li inventory loss and Al corrosion in 4 M LiFSI/DME electrolyte simultaneously. On the anode side, the IL additive facilitates the formation of a robust Li3N- and LiF-rich solid electrolyte interphase, promoting highly reversible Li plating/stripping and uniform Li deposition. Additionally, the ILs alter the Li+ solvation structure, leading to enhanced tLi+ and rapid Li+ desolvation kinetics. Concurrently, on the cathode side, the ILs aid in the generation of dense LiF- and AlF-rich passivation films against Al corrosion. By using the IL-added electrolyte, the Cu||LiMn0.7Fe0.3PO4 cell operates stably at 4.5 V, and the Cu||NCM613 cell with a high loading of 4.0 mA h cm-2 sustains 142 cycles until 80% capacity retention. This research contributes to a deeper understanding of the IL additive mechanism at the electrode-electrolyte interfaces and offers a straightforward approach to designing practical high-voltage AFLMB electrolytes.

Modulating the Inner Helmholtz Plane towards Stable Solid Electrolyte Interphase by Anion-π Interactions for High-Performance Anode-Free Lithium Metal Batteries.

Anode-free lithium (Li) metal batteries (AFLBs) featured high energy density are viewed as the viable future energy storage technology. However, the irregular Li deposition and unstable solid electrolyte interphase (SEI) on anode current collectors reduce their cycling performance. Here, we propose a concept of anion-recognition electrodes enabled by anion-π interactions to regulate the inner Helmholtz plane (IHP) and electrolyte solvation chemistry for high-performance AFLBs. By engineering the electrodes with electron-deficient aromatic-π systems that possess high permanent quadrupole moment (Qzz), the anion-π interactions can be generated to concentrate the anions on the electrode surface and tune the IHP structure to construct a stable anion-derived SEI layer, thus achieving highly reversible Li plating/stripping process. Through designing various current collectors with different Qzz values, the intimate correlations among the surface charge of the electrode, competitive adsorption of the IHP, and SEI structures are demonstrated. Particularly, the modified carbon cloth current collector with a high Qzz value (+35.1) delivers a high average Li stripping/plating Coulombic efficiency of 99.1 % over 230 cycles in the carbonated electrolyte, enabling a long lifespan and high capacity retention of LiNi0.8Co0.1Mn0.1O2-based AFLBs with a commercial-level areal capacity (4.1 mAh cm-2).

Entropy Increase in Electrolytes for Practical Anode‐Free Lithium Metal Batteries with High‐Loading Cathodes and Lean Electrolyte

AbstractAn effective concept of using entropy increase to regulate the nanoscale solvation structure has been proposed to enhance the cycle performance of anode‐free lithium metal batteries (AFLMBs). It includes two mainstream types: entropy increase driven by multiple salts or solvents. However, most current research is based on low‐loading cathodes and mAh‐level battery systems. The relationship between the increase in entropy and practical battery with different high‐loading cathodes and Ah‐levels is seldom reported. In this paper, two mainstream methods of entropy increase are compared, and the relationship of their kinetics parameters, solid electrolyte interphase formation, and cycling performances are studied. It is found that the entropy increases driven by multiple‐solvents are more favorable to the pouch cell with high‐loading cathode and lean electrolytes. The coin cell consists of a copper current collector and a high‐loading cathode (10.5 mg cm−2) performs 40 cycles at discharge rates of 0.5 C, while the cell with a conventional ester electrolyte only last 10 cycles. A large‐capacity pouch cell (4 Ah), with a high‐loading cathode (7.6 mAh cm−2, single side) and lean electrolyte of 1.3 g Ah−1, achieves 500 Wh kg−1 and 20 cycles.

Janus-Architectured Lithium Replenishment Separators Boosting Longevity of Anode-Free Lithium Metal Batteries.

Addressing the issue of inactive dead lithium deposition on the anode side remains a significant challenge for anode-free lithium metal batteries. While lithium compensation techniques can mitigate lithium depletion, directly introducing lithium compounds into the cathode material may degrade the electrode structure. Here the design and fabrication of a novel lithium replenishment separator (LRS) using a lithium compensation agent of Li2C4O4 is reported. The electrospun LRS demonstrates excellent ionic conductivity of 1.82 mS cm-1 and a high Li+ transference number of 0.51. Such a functionalized LRS not only provides additional active lithium for anode-free lithium metal batteries but also promotes uniform deposition of lithium metal. Compared with conventional polyolefin-based separators, the LRS effectively boosts LiFePO4||Cu anode-free batteries with enhanced cyclability. These results suggest this LRS strategy can find promising applications in next-generation anode-free batteries with high energy densities.

Formulating Electrolytes for 4.6 V Anode-Free Lithium Metal Batteries

High-voltage initial anode-free lithium metal batteries (AFLMBs) promise the maximized energy densities of rechargeable lithium batteries. However, the reversibility of the high-voltage cathode and lithium metal anode is unsatisfactory in sustaining their long lifespan. In this research, a concentrated electrolyte comprising dual salts of LiTFSI and LiDFOB dissolved in mixing solvents of dimethyl carbonate (DMC) and fluoroethylene carbonate (FEC) with a LiNO3 additive was formulated to address this challenge. FEC and LiNO3 regulate the anion-rich solvation structure and help form a LiF, Li3N-rich solid electrolyte interphase (SEI) with a high lithium plating/stripping Coulombic efficiency of 98.3%. LiDFOB preferentially decomposes to effectively suppress the side reaction at the high-voltage operation of the Li-rich Li1.2Mn0.54Ni0.13Co0.13O2 cathode. Moreover, the large irreversible capacity during the initial charge/discharge cycle of the cathode provides supplementary lithium sources for cycle life extension. Owing to these merits, the as-fabricated AFLMBs can operate stably for 80 cycles even at an ultrahigh voltage of 4.6 V. This study sheds new insights on the formulation of advanced electrolytes for highly reversible high-voltage cathodes and lithium metal anodes and could facilitate the practical application of AFLMBs.

In-situ construction of high-performance artificial solid electrolyte interface layer on anode surfaces for anode-free lithium metal batteries

The electrochemical performance of lithium metal batteries (LMBs) was hampered by the uncontrolled growth of lithium (Li) dendrites. To address this issue, the extensive application of artificial solid electrolyte interphase (SEI) coatings on anode surfaces emerged as an effective solution. Electrospinning, as an innovative technique for fabricating artificial SEI layers on the surface of copper (Cu) foil, effectively mitigated Li volume strain during cycling. In this study, an electrospun organic–inorganic composite nanofiber membrane was in-situ fabricated on Cu foil, serving as an artificial SEI layer (CuWs) for anode-free LMBs (AF-LMBs) to enhance battery performance. Lithiophilic polyvinylpyrrolidone was used as the polymer matrix, and Cu nitrate served as the inorganic functional particles capable of in-situ redox reactions. The CuWs with their three-dimensional (3D) network structure accommodated electrode volume changes and suppressed Li dendrite growth during Li deposition and stripping. Additionally, CuWs facilitated the in-situ generation of Li nitrate (LiNO3), which helped stabilize SEI layer and enhance Li utilization. The release sites of LiNO3 on the nanofibers enabled the in-situ reduction of metallic Cu, providing nucleation sites for Li deposition and forming the 3D ion–electron hybrid conductive networks. This CuWs layer reduced interfacial resistance and nucleation barriers, promoting uniform Li+ distribution on the anode surface. Li-Cu cells incorporating CuWs exhibited remarkable cycling stability, enduring over 460 cycles at 1.0 mA cm−2 and 1.0 mAh cm−2 with an average Coulombic efficiency of over 98.6 %. In Li-poor cells, the LFP|PE|CuWs achieved stable cycling for more than 30 cycles at 1.0 C, with a capacity retention rate of 92.0 %. These findings demonstrated that the CuWs membrane significantly enhanced the electrochemical performance of Li-poor cells and provided a novel artificial SEI protective strategy for advanced AF-LMBs with high energy density.

Anode-Free Li Metal Batteries: Feasibility Analysis and Practical Strategy.

Energy storage devices are striving to achieve high energy density, long lifespan, and enhanced safety. In view of the current popular lithiated cathode, anode-free lithium metal batteries (AFLMBs) will deliver the theoretical maximum energy density among all the battery chemistries. However, AFLMBs face challenges such as low plating-stripping efficiency, significant volume change, and severe Li-dendrite growth, which negatively impact their lifespan and safety. This study provides an overview and analysis of recent progress in electrode structure, characterization, performance, and practical challenges of AFLMBs. The deposition behavior of lithium is categorized into two stages: heterogeneous and homogeneous interface deposition. The feasibility and practical application value of AFLMBs are critically evaluated. Additionally, key test models, evaluation parameters, and advanced characterization techniques are discussed. Importantly, practical strategies of different battery components in AFLMBs, including current collector, interface layer, solid-state electrolyte, liquid-state electrolyte, cathode, and cycling protocol, are presented to address the challenges posed by the two types of deposition processes, lithium loss, crosstalk effect and volume change. Finally, the application prospects of AFLMBs are envisioned, with a focus on overcoming the current limitations and unlocking their full potential as high-performance energy storage solutions.

Constructing stable solid electrolyte interphases to enhance the calendar life of anode-free lithium metal batteries

Advancement of anode-free lithium metal batteries (AFLMBs) has been appreciated due to their exceptional volumetric energy density and manufacturing simplicity. However, AFLMBs suffer from poor cycle performance due to the absence of excess lithium and current research lacks an understanding of lithium corrosion and calendar aging in AFLMBs. Here, we investigate the practical effects of chemical and galvanic corrosion on battery performance (calendar life) through a modified full-cell cycling experiment. The impact of galvanic corrosion is negligible, whereas chemical corrosion during a rest period reduces the capacity retention (CR) from 47% to 32% over 100 cycles. Consequently, a corrosion control strategy is implemented, substituting 1,2-dimethoxyethane with 1,2-dimethoxypropane (DMP), which has weaker lithium ion solvation properties due to its inductive effect. This approach results in the formation of a Li2O-rich solid-electrolyte interphase (SEI) layer, which effectively prevents direct contact of lithium with the electrolyte and the formation of additional SEI layers. Consequently, the decrease in CR due to chemical corrosion is considerably mitigated in DMP-based electrolyte, with only a slight decrease from 51% to 49%. This study provides insights into lithium corrosion in practical AFLMBs and offers guidelines for designing less-corrosive electrolytes to improve AFLMB performance for diverse industrial applications as energy-storage devices.

Engineering Moderately Lithiophilic Paper-Based Current Collectors with Variable Solid Electrolyte Interface Films for Anode-Free Lithium Batteries.

Compared to traditional lithium metal batteries, anode-free lithium metal batteries use bare current collectors as an anode instead of Li metal, making them highly promising for mass production and achieving high-energy density. The current collector, as the sole component of the anode, is crucial in lithium deposition-stripping behavior and greatly impacts the rate of Li depletion from the cathode. In this study, to investigate the lithiophilicity effect of the current collector on the solid electrolyte interface (SEI) film construction and cycling performance of anode-free lithium batteries, various lightweight paper-based current collectors were prepared by electroless plating Cu and lipophilic Ag on low-dust paper (LDP). The areal densities of the as-prepared LDP@Cu, LDP@Cu-Ag, and LDP@Ag were approximately 0.33 mg cm-2. The use of lipophilic Ag-coated collectors with varying loadings allowed for the regulation of lipophilicity. The impacts of these collectors on the distribution of SEI components and Li depletion rate in common electrolytes were investigated. The findings suggest that higher loadings of lipophilic materials, such as Ag, on the current collector increase its lipophilicity but also lead to significant Li depletion during the cycling process in full-cell anode-free Li metal batteries. Thus, moderately lithiophilic current collectors, such as LDP@Cu-Ag, show more potential for Li deposition and striping and stable SEI with a low speed of Li depletion.