Li Dendrite Formation Research Articles

High Young's Modulus Li6.4La3Zr1.4Ta0.6O12-Based Solid Electrolyte Interphase Regulating Lithium Deposition for Dendrite-Free Lithium Metal Anode.

Artificial solid electrolyte interphase (SEI) layers have been widely regarded as an effective protection for lithium (Li) metal anodes. In this work, an artificial SEI film consisting of dense Li6.4La3Zr1.4Ta0.6O12 (LLZTO) nanoparticles and polymerized styrene butadiene rubber is designed, which has good mechanical and chemical stability to effectively prevent Li anode corrosion by the electrolyte. The LLZTO-based SEI film can not only guide Li to uniformly deposit at the interface but also accelerate the electrochemical reaction kinetics due to its high Li+ conductivity. In particular, the high Young's modulus of the LLZTO-based SEI will regulate e- distribution in the continuous Li plating/stripping process and achieve uniform deposition of Li. As a consequence, the Li anode with LLZTO-based SEI (Li@LLZTO) enables symmetric cells to demonstrate a stable overpotential of 25 mV for 600 h at a current density of 1 mA cm-2 for 1 mA h cm-2. The Li@LLZTO||LFP (LiFePO4) full cell exhibits a capacity of 106 mA h g-1 after 800 cycles at 5 C with retention as high as 90%. Our strategy here suggests that the artificial SEI with high Young's modulus effectively inhibits the formation of Li dendrites and provides some guidance for the design of higher performance Li metal batteries.

Promising AlN-modified VS2 heterostructure for Li-ion battery anode with high specific capacity

Degradation of the interior structure and the formation of uncontrolled Li dendrites at the negative electrode during the process of detaching and embedding Li atoms in lithium-ion batteries (LIBs) can negatively impact the cycling operation of the battery. To address these shortcomings, we constructed AlN/VS2 heterostructure with the expectation that it can be deployed as anodes in LIBs. Our results show that the AlN/VS2 heterostructure is characterized by strong stability, enhanced electrical conductivity and mechanical properties compared to monolayer AlN and VS2. Small Li clusters and cross-layer adsorption models are not thermodynamically prone to form, implying that the anode material plays a positive role in inhibiting the formation of dendrites. Moreover, the specific capacity of the AlN/VS2 heterostructure is 816.2 mAh/g, which is higher than that of monolayer VS2 (466 mAh/g) and graphene (372 mAh/g). The results of ab-initio molecular dynamics (AIMD) and biaxial stretching further demonstrate the structural and electrochemical stability of the electrode material during the embedding of Li atoms. To sum up, the AlN/VS2 heterostructure show potential as a high-performance anode for utilization in LIBs.

Surface fluorination of nickel nanowires enabling LiF-rich nanoscale solid electrolyte interface for stable lithium anodes

Lithium (Li) metal has become a research hotspot for anodes materials due to its ultra-high theoretical capacity and the lowest redox potential. However, the practical application of Li metal batteries is hampered by the formation of uncontrollable Li dendrites and the irreversible structural changes during long-term charge/discharge processes. Developing stable Li metal anode with uniform Li deposition is highly desirable. Herein, surface fluorination of nickel nanowires enabling LiF-rich nanoscale solid electrolyte interface was demonstrated for stable Li anodes. Free-standing three-dimensional (3D) nickel nanowires (NiNWs) current collector decorated with lithiophilic NiF2 nanosheets (NiNWs@NiF2) was constructed via a simple and scalable fluorination strategy. Theoretical and experimental analysis confirmed that the lithiophilic surface of NiF2 nanosheets could reduce the Li nucleation barrier, facilitating uniform Li ion deposition. The 3D conductive NiNWs network enabled fast electron transfer and mitigated volume changes during cycling. Additionally, a LiF-rich nanoscale solid electrolyte interface (SEI) layer formed between Li and the electrolyte significantly improved the interfacial stability. As a result, the as-assembled Li-NiNWs@NiF2 symmetrical cell provided a superior electrochemical performance, maintaining stability for 2500 h at 1.0 mA cm−2 and 900 h at 5.0 mA cm−2. Furthermore, the assembled Li-NiNWs@NiF2|| LiFePO4 (LFP) full cell demonstrated exceptional capacity retention of 93.9 % after 2000 cycles at a rate of 5C. Overall, the unique structure of NiNWs@NiF2 not only offers a straightforward method for designing a 3D lithiophilic host, but also provides the concept of interfacial engineering through the in-situ construction of an artificial LiF-rich nanoscale SEI layer.

Oriented Structures for High Safety, Rate Capability, and Energy Density Lithium Metal Batteries.

Lithium metal batteries (LMBs) have emerged in recent years as highly promising candidates for high-density energy storage systems. Despite their immense potential, mutual constraints arise when optimizing energy density, rate capability, and operational safety, which greatly hinder the commercialization of LMBs. The utilization of oriented structures in LMBs appears as a promising strategy to address three key performance barriers: 1) low efficiency of active material utilization at high surface loading, 2) easy formation of Li dendrites and damage to interfaces under high-rate cycling, and 3) low ionic conductivity of solid-state electrolytes in high safety LMBs. This review aims to holistically introduce the concept of oriented structures, provide criteria for quantifying the degree of orientation, and elucidate their systematic effects on the properties of materials and devices. Furthermore, a detailed categorization of oriented structures is proposed to offer more precise guidance for the design of LMBs. This review also provides a comprehensive summary of preparation techniques for oriented structures and delves into the mechanisms by which these can enhance the energy density, rate capability, and safety of LMBs. Finally, potential applications of oriented structures in LMBs and the crucial challenges that need to be addressed in this field are explored.

High performance gel polymer electrolyte based on P(MMA-co-Sty) and PVDF blend for fast-charging lithium metal batteries with extended cycle life

In the quest for high-energy-density lithium metal batteries (LMBs), the stabilization of lithium (Li) metal anodes during fast charging remains a formidable challenge. In this study, a novel copolymer, Poly(methyl methacrylate-co-styrene) (namely PMS) is synthesized and blended with Poly(vinylidene fluoride) to fabricate a porous gel polymer electrolyte (GPE, namely PMS-PVDF) through the nonsolvent-induced phase separation technique, which significantly enhances the electrochemical stability and fast-charging capabilities of LMBs. The developed GPE exhibits a high ionic conductivity of 5.62 mS cm−1, thereby reducing the formation of detrimental Li dendrites and leading to over 400 h stripping/plating process at 0.5 mA cm−2. Extensive electrochemical tests show that the LMBs with the obtained PMS-PVDF GPE achieve exceptional cycle stability over 600 and 1000 cycles at the C-rates of 0.5 and 3 C, respectively, outperforming traditional electrolytes. Furthermore, the ultra-stability of the quasi-solid-state electrolyte is demonstrated in a 375 mAh pouch cell setup, suggesting an essential trait for the practical application of high-power devices. This work marks a pivotal contribution to the field of energy storage, delivering insights and a clear methodology that pave the way for the development of next-generation LMBs poised for commercial viability.

Cyclability Investigation of Anode-Free Lithium-Metal Batteries

Lithium (Li) is a sought-after element for thrift, and considerable effort is being invested in conserving, reusing, and optimizing its chemical capabilities as a key material for energy storage systems. Anode-free lithium-metal batteries (AFLMB) provide the ability to utilize the exact amount of Li in the battery, thereby increasing both the specific capacity and safety of the battery. AFLMBs are widely recognized and investigated due to their promised benefits but have not yet become commercial, primarily because they suffer from uneven Li deposition. This issue results in Li dendrite formation, electrolyte consumption due to poor solid electrolyte interphase properties, and, generally, safety concerns. Overcoming these challenges would bring humanity one step closer to a desirable zero-carbon emission future, as more energy could be stored in less volume and weight. In this study, we examined an AFLMB system and investigated different physical and electrochemical factors to understand their effects on the nature of Li deposition/dissolution processes and on the cyclability of the battery. The effects of electrode architecture, cycling temperature, current density in the first charge, and salt composition on the battery were investigated using electrochemical impedance spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy.

Unlocking high-energy solid-state lithium-sulfur batteries with an innovative double-layer hybrid solid electrolyte

This study developed a novel double-layer hybrid solid electrolyte (DLHSE) to address the limitations of solid-state lithium–sulfur (Li–S) batteries, which include poor electronic/ionic conductivity, interfacial chemical/electrochemical instability, and substantial interfacial resistance between the solid electrolyte and electrodes. The DLHSE comprises an ion-conducting ceramic, electrochemically stable polymer, and ether-based liquid electrolyte. Specifically, the dual-layer ceramic skeleton comprises an inorganic NASICON-type Li1+xAlxTi2-x(PO4)3 (LATP) layer facing the cathode to facilitate Li+ migration at the interface and a garnet-type Li7La3Zr2O12 (LLZO) layer facing the anode to suppress Li dendrite formation and mitigate the “shuttle effect”. The polymer binder (PVDF–TrFE) can create a three-dimensional network to enhance structural compactness and stability. The penetrating ether-based electrolyte can facilitate Li+ transfer and reinforce the interfacial contact. Furthermore, a well-designed porous carbon rod/sulfur (PCR/S) composite with an ultrahigh sulfur content of 80 wt% was prepared as the cathode. Consequently, the novel structural configuration with PCR/S cathode and DLHSE, not only demonstrated excellent coin-cell performance with a capacity retention of 802 mAh g−1 after 500 cycles at 0.2C, but also an outstanding A-h-level pouch cell with an impressive discharge capacity of 7 Ah at 0.1C.

Modulation of Li+ microenvironment in liquid electrolyte for interface design of Li‐metal anodes

AbstractWhile lithium metal anodes (LMAs) offer the highest energy density, positioning them as a promising material for graphite, they suffer from uneven electroplating morphology and the formation of Li dendrites. Given the pivotal role of the solid‐electrolyte interphase (SEI), which is formed by electrolyte decomposition, in mitigating dendritic growth, extensive research has been conducted on liquid electrolytes in Li metal batteries (LMBs). This mini‐review presents the historical advancements in LMB electrolytes, focusing on modulating the Li+ microenvironment and LMA interface chemistry to inhibit Li dendrite formation. We traced the evolution of LMB electrolytes from traditional formulations to advanced designs. In particular, the reinforcement of the SEI and the compact morphology of the deposited Li are deeply discussed at each advancement in liquid electrolytes. We subsequently identify common characteristics among these advanced electrolytes and conclude by discussing future directions and strategies for rational design.

Dual-Component Interlayer Enables Uniform Lithium Deposition and Dendrite Suppression for Solid-State Batteries.

β-Lithium thiophosphate (LPS) exhibits high Li+ conductivity and has been identified as a promising ceramic electrolyte for safe and high-energy-density all-solid-state batteries. Integrating LPS into solid-state lithium (Li) batteries would enable the use of a Li electrode with the highest deliverable capacity. However, LPS-based batteries operate at a limited current density before short-circuiting, posing a major challenge for the development of application-relevant batteries. In this work, we designed a dual-component interfacial protective layer called LiSn-LiN that forms in situ between the Li electrode and LPS electrolyte. The LiSn component, Li22Sn5, exhibits enhanced Li diffusivity compared with the metallic lithium and facilitates a more uniform lithium deposition across the electrode surface, thus eliminating Li dendrite formation. Meanwhile, the LiN component, Li3N, shows enhanced mechanical stiffness compared with LPS and functions to suppress dendrite penetration. This chemically robust LiSn-LiN interlayer provides a more than doubled deliverable critical current density compared to systems without interfacial protection. Through combined XPS and XAFS analyses, we determined the local structure and the formation kinetics of the key functional Li22Sn5 phase formed via the electrochemical reduction of a Sn3N4 precursor. This work demonstrates an example of the structural-specific design of a protective interlayer with a desired function - dendrite suppression. The structure of a functional protective layer for a given solid-state battery should be tailored based on the given battery configuration and its unique interfacial chemistry.

Boosted Li+ transport ensured by high-entropy Prussian blue analogues with tuned PF6− adsorption for stable Li metal anode

The inhomogeneous lithium metal (Li) deposition and low lithium ion (Li+) mobility lead to the formation and growth of Li dendrites, which impede the desirable performance of Li metal batteries (LMBs) with high energy density in widely practical applications. Herein, a high-entropy MnCoNiCuZn-Prussian blue analogue (HE-PBA) is utilized to modify the commercial polypropylene separator (PP@HE-PBA), which will form an artificial protective layer on the surface of Li. The polar –CN groups of HE-PBA can enhance the wettability of PP to the electrolyte, while the movement of PF6− anions are flexibly tuned by the appropriate absorption ability and synergistic effect of multiple metal ions in HE-PBA. A high Li+ transference number of 0.69 is achieved, which can relieve the Li+ concentration polarization, regulate the Li+ flow, and realize the uniform Li deposition. With PP@HE-PBA, the Li||Li symmetric cells display durability up to 600 h in the ester-based electrolyte at 1 mA cm−2 for 1 mAh cm−2. Also, the PP@HE-PBA exhibits great potential in LMBs, where the Li4Ti5O12 (LTO) ||Li and sulfated polyacrylonitrile (S-PAN) ||Li batteries deliver superior cycling performance to those without PP@HE-PBA.

Constructing Reversible Li Deposition Interfaces by Tailoring Lithiophilic Functionalities of a Heteroatom-Doped Graphene Interlayer for Highly Stable Li Metal Anodes.

Lithium (Li) metal has been regarded as the ideal anode for rechargeable batteries due to its low reduction potential and high theoretical capacity. However, the formation of fatal Li dendrites during repeated cycling shortens the battery life and causes serious safety concerns. Functionalized separators with electrically conductive and lithiophilic coating layers potentially inhibit dendrite formation and growth on Li metal anodes by providing nucleation sites for reversible Li deposition/stripping. In this work, we propose functionalized separators incorporating heteroatom-doped (N or B) graphene interlayers to modulate the Li nucleation behavior. The electronegative N-doping and electropositive B-doping were investigated to understand their regulation of the Li deposition behavior. With the heteroatom-doped graphene-coated separators, we observe significantly improved cycling stability along with enhanced charge transfer kinetics and low Li nucleation overpotential. This is attributed to the heteroatom-doped graphene interlayer expanding the surface area of the Li metal anode while providing additional space for uniform Li deposition/stripping, thus preventing undesirable side reactions. As a result, the formation of dendrites and pits on the Li metal anode surface is suppressed, demonstrating the protective effect of the Li metal anode. Interestingly, N-doped graphene-coated separators exhibit lower Li nucleation overpotentials than B-doped graphene-coated separators but rather lower average Coulombic efficiencies and reduced cycling stability. This implies that adequate adsorption on B-based sites, as opposed to the strong adsorption on N-based sites, improves the reversibility. Notably, the Li adsorption strength of the lithiophilic functional groups critically affects the reversibility, as observed by Li nucleation barrier measurements and atomistic simulations. This work suggests that interface engineering using conductive and lithiophilic materials can be a promising strategy for controlling Li deposition in advanced Li metal batteries.

Laser‐Constructing 3D Copper Current Collector with Crystalline Orientation Selectivity for Stable Lithium Metal Batteries

The practical application of lithium (Li) metal anodes in high‐capacity batteries is impeded by the formation of hazardous Li dendrites. To address this challenge, this research presents a novel methodology that combines laser ablation and heat treatment to precisely induce controlled grain growth within laser‐structured grooves on copper (Cu) current collectors. Specifically, this approach enhances the prevalence of Cu (100) facets within the grooves, effectively lowering the overpotential for Li nucleation and promoting preferential Li deposition. Unlike approaches that modify the entire surface of collectors, our work focuses on selectively enhancing lithiophilicity within the grooves to mitigate the formation of Li dendrites and exhibit exceptional performance metrics. The half‐cell with these collectors maintains a remarkable Coulombic efficiency of 97.42% over 350 cycles at 1 mA cm−2. The symmetric cell can cycle stably for 1600 h at 0.5 mA cm−2. Furthermore, when integrated with LiFePO4 cathodes, the full‐cell configuration demonstrates outstanding capacity retention of 92.39% after 400 cycles at a 1C discharge rate. This study introduces a novel technique for fabricating selective lithiophilic three‐dimensional (3D) Cu current collectors, thereby enhancing the performance of Li metal batteries. The insights gained from this approach hold promise for enhancing the performance of all laser‐processed 3D Cu current collectors by enabling precise lithiophilic modifications within complex structures.

Engineering High-Performance Li Metal Batteries through Dual-Gradient Porous Cu-CuZn Host.

Porous copper (Cu) current collectors show promise in stabilizing Li metal anodes (LMAs). However, insufficient lithiophilicity of pure Cu and limited porosity in three-dimensional (3D) porous Cu structures led to an inefficient Li-Cu composite preparation and poor electrochemical performance of Li-Cu composite anodes. Herein, we propose a porous Cu-CuZn (DG-CCZ) host for Li composite anodes to tackle these issues. This architecture features a pore size distribution and lithiophilic-lithiophobic characteristics designed in a gradient distribution from the inside to the outside of the anode structure. This dual-gradient porous Cu-CuZn exhibits exceptional capillary wettability to molten Li and provides a high porosity of up to 66.05%. This design promotes preferential Li deposition in the interior of the porous structure during battery operation, effectively inhibiting Li dendrite formation. Consequently, all cell systems achieve significantly improved cycling stability, including Li half-cells, Li-Li symmetric cells, and Li-LFP full cells. When paired synergistically with the double-coated LiFePO4 cathode, the pouch cell configured with multiple electrodes demonstrates an impressive discharge capacity of 159.3 mAh g-1 at 1C. We believe this study can inspire the design of future 3D Li anodes with enhanced Li utilization efficiency and facilitate the development of future high-energy Li metal batteries.

V-MOF-derived V2O5 nanoparticles-modified carbon fiber cloth-based dendrite-free anode for high-performance lithium metal batteries

At present, commercial Li-ions batteries are hardly to satisfy the growing demand for high energy density, for this purpose, lithium (Li) metal batteries (LMBs) have attracted worldwide attention in recent years. However, its practical applications are hindered by the formation of Li dendrites and volume effect during Li plating/stripping process, which leads to a lot of safety hazards. Herein, we firstly employed MOF-derived V2O5 nanoparticles to decorate the carbon fiber cloth (CFC) backbone to acquire a lithiophilic 3D porous conductive framework (CFC@V2O5). Subsequently, the CFC@V2O5 skeleton was permeated with molten Li to prepare CFC@V2O5@Li composite anode. the CFC@V2O5@Li composite anode can be stably cycled for more than 1650 h at high current density (5 mA cm–2) and areal capacity (5 mA·h cm–2). The prepared full cell can initially maintain a high capacity of about 143 mA·h g–1 even at a high current density of 5 C, and can still maintain 114 mA·h g–1 after 1000 cycles.

Constructing lithiophilic sites–rich artificial solid electrolyte interphase to enable dendrite−free and corrosion−free lithium–sulfur batteries

An artificial solid electrolyte interphase (SEI) with lithiophilic sites and chemical bonds anchoring lithium polysulfides (LiPSs) has been developed as a potential solution to protect the lithium (Li) metal anode of Lithium−sulfur (Li–S) batteries. This strategy aims to guide consistent Li deposition and relieve lithium corrosion. Herein, the evolution process of lithiophilic sites based on aluminum fluoride (AlF3) in an artificial SEI is disclosed in Li–S batteries with metal−based lithiophilic sites. The polyester polymer (PMMA and PPC)/AlF3 artificial SEI (MPAF−SEI) was homogeneously anchored on Li anode by in−situ polymerization. The conversion of AlF3 into Li–Al and LiF lithiophilic sites effectively reduce the Li nucleation overpotential and prevents the formation of Li dendrites. At the same time, the polymer can anchor LiPSs by chemical bonds and prevents Li corrosion. The optimized MPAF−SEI protected Li demonstrates excellent stability for over 3000 h at a capacity of 1 mAh cm−2 in Li || Li symmetric cells. The Li–S battery with low N/P (4) exhibits a capacity of 532.6 mAh g −1 over 300 cycles lifespan at 0.5C.

Deciphering the degradation mechanism of thick graphite anodes in high-energy-density Li-ion batteries by electrochemical impedance spectroscopy

The utilization of thick electrodes represents a promising strategy for high energy density batteries, but practical application is hindered by the observed challenges of low cyclic stability and rate performance. To address these issues, we employed electrochemical impedance spectroscopy (EIS) as a non-destructive method to establish a diagnostic model capable of identifying the causes of the instability of thick electrodes. While EIS models for thick electrodes have previously been discussed, the connection between these models and the degradation mechanism has yet to be fully understood. Our investigation revealed that resistances of the current collector, solid electrolyte interphase, or electrolyte, increase with the increment of electrode thickness and further increases following the cycling test with a similar degree, indicating that the degradation of thick electrodes is not governed by those resistances. Rather, a new resistance component emerged in the thick electrode after the cycling test, indicating the emerged resistance plays as the predominant factor driving degradation. The new resistance component on the impedance spectra is linked to Li dendrite formation, due to impeded Li-ion transfer. The hindered Li-ion movement is probably due to the migration of low-weight molecules in the drying process and/or the extended distance Li-ions must transverse.

Ultrathin, Mechanically Durable, and Scalable Polymer-in-Salt Solid Electrolyte for High-Rate Lithium Metal Batteries.

Polymer-in-salt solid-state electrolytes (PIS SSEs) are emerging for high room-temperature ionic conductivity and facile handling, but suffer from poor mechanical durability and large thickness. Here, Al2O3-coated PE (PE/AO) separators are proposed as robust and large-scale substrates to trim the thickness of PIS SSEs without compromising mechanical durability. Various characterizations unravel that introducing Al2O3 coating on PE separators efficiently improves the wettability, thermal stability, and Li-dendrite resistance of PIS SSEs. The resulting PE/AO@PIS demonstrates ultra-small thickness (25µm), exceptional mechanical durability (55.1MPa), high decomposition temperature (330°C), and favorable ionic conductivity (0.12 mS cm-1 at 25°C). Consequently, the symmetrical Li cells remain stable at 0.1mA cm-2 for 3000 h, without Li dendrite formation. Besides, the LiFePO4|Li full cells showcase excellent rate capability (131.0 mAh g-1 at 10C) and cyclability (93.6% capacity retention at 2C after 400 cycles), and high-mass-loading performance (7.5mg cm-2). Moreover, the PE/AO@PIS can also pair with nickel-rich layered oxides (NCM811 and NCM9055), showing a remarkable specific capacity of 165.3 and 175.4 mAh g-1 at 0.2C after 100 cycles, respectively. This work presents an effective large-scale preparation approach for mechanically durable and ultrathin PIS SSEs, driving their practical applications for next-generation solid-state Li-metal batteries.

Lithiophilic ZnCu alloy sites on copper current collector for high performance Li metal anode

Lithium (Li) metal has been widely regarded as the optimal anode material for the high-energy density rechargeable batteries, due to its ultrahigh theoretical specific capacity and lowest electrochemical potential. However, the formation of Li dendrites presents a significant safety concern, which limits its practical application. In this paper, to address this issue, an efficient and cost-effective strategy was proposed to prepare a zinc-copper composite collector (ZCC) with outstanding electrochemical performance, which can effectively suppress the formation of lithium dendrites. The lithophilic surface with ZnCu alloy nanoparticles was achieved through physical vapor deposition followed by annealing treatment. The ZCC collector enables dendrite-free deposition of Li due to its negligible nucleation overpotential. Even at high area capacity of 3 mAh cm−2 at 1 mA cm−2 in half-cells, the ZCC exhibits exceptional cycling performance and high coulomb efficiency. Preloaded with Li, the composite electrode (Li/ZCC) delivers an enhanced lifespan with low overpotential evidently. Matched with LiFePO4 (LFP) cathode, LFP||Li/ZCC full cells reveal a superior cycling stability with enhanced capacity retention of 85 % (after 1000 cycles at 1 C) and 87 % (after 800 cycles at 3 C) respectively.

Thermodynamics, Adhesion, and Wetting at Li/Cu(-Oxide) Interfaces: Relevance for Anode-Free Lithium-Metal Batteries.

A rechargeable battery that employs a Li metal anode requires that Li be plated in a uniform fashion during charging. In "anode-free" configurations, this plating will occur on the surface of the Cu current collector (CC) during the initial cycle and in any subsequent cycle where the capacity of the cell is fully accessed. Experimental measurements have shown that the plating of Li on Cu can be inhomogeneous, which can lower the efficiency of plating and foster the formation of Li dendrites. The present study employs a combination of first-principles calculations and sessile drop experiments to characterize the thermodynamics and adhesive (i.e., wetting) properties of interfaces involving Li and other phases present on or near the CC. Interfaces between Li and Cu, Cu2O, and Li2O are considered. The calculations predict that both Cu and Cu2O surfaces are lithiophilic. However, sessile drop measurements reveal that Li wetting occurs readily only on pristine Cu. This apparent discrepancy is explained by the occurrence of a spontaneous conversion reaction, 2 Li + Cu2O → Li2O + 2 Cu, that generates Li2O as one of its products. Calculations and sessile drop measurements show that Li does not wet (newly formed) Li2O. Hence, Li that is deposited on a Cu CC where surface oxide species are present will encounter a compositionally heterogeneous substrate comprising lithiophillic (Cu) and lithiophobic (Li2O) regions. These initial heterogeneities have the potential to influence the longer-term behavior of the anode under cycling. In sum, the present study provides insights into the early stage processes associated with Li plating in anode-free batteries and describes mechanisms that contribute to inefficiencies in their operation.

Engineering of lithiophilic hosts for stable lithium metal anodes

Lithium (Li0) metal has been deemed the desired anode for the future of cutting-edge rechargeable Li batteries benefiting from its lowest reduction potential and ultrahigh theoretical specific capacity. Nevertheless, the large-scale applications of Li metal batteries are restricted by scattered Li dendrite formation and uncontrollable volume expansion. To address these issues, a currently prevalent measure is to use structured lithiophilic hosts for Li metal. The enhanced lithiophilicity of hosts is significant for regulating the Li nucleation barrier. By virtue of these lithiophilic measures, the Li nucleation sites will be well controlled and the Li plating layer will be more stable. Through this article, we classified various lithiophilic hosts and described their applications for Li metal batteries, including heteroatom-doping carbon, lithiophilic-material loading hosts and gradient skeletons. We discussed the inherent advantages and lithophilic mechanisms of these hosts on optimizing the lithophilic properties and analyzed various factors that induced the formation of dendrite Li. Moreover, the review outlines the current challenges and perspectives for Li metal anodes, and some understanding of the lithiophilic chemistry is given.