Li Foil Research Articles

Evaluating Pressure‐dependent Discharge Behavior of Foil Versus In situ Plated Lithium Metal Anodes in Solid‐State Batteries

AbstractAnode‐free manufacturing of solid‐state batteries (SSBs) shows promise to maximize energy density by eliminating excess lithium (Li) and simplifying battery production. However, high reversibility during discharge (stripping of Li) is necessary for long‐lifetime SSBs with a limited Li reservoir. Further, the plastic flow of Li changes depending on the Li thickness, leading to possible differences in discharge performance under stack pressure. This work investigates the pressure‐dependent discharge performance of anode‐free manufactured SSBs with in situ plated Li and compares the performance to that of conventional thick Li foil cells. Distinct stripping behavior is observed at low pressures (0–1 MPa), where Li diffusivity and initial interfacial contact may control accessible capacity, compared to high pressures (3–10 MPa) where mechanical deformation of Li likely governs stripping behavior. Analysis of impedance spectra collected during stripping shows that additional stack pressure delays the formation of deep, as opposed to lateral, voids in the Li anode. These results provide insights to guide the transition from thick Li foil anodes to anode‐free manufactured SSBs.

Functional Separator with Poly(Acrylic Acid)-Enabled Li2CO3-Free Garnet Coating for Long-Cycling Lithium Metal Batteries.

Lithium metal batteries (LMBs) possess a theoretical energy density far surpassing that of commercial lithium-ion batteries (LIBs), positioning them as one of the most promising next-generation energy storage systems. Modifying separators with composite coatings comprising oxide solid-state electrolyte (SSE) particles and polymers can improve the cycling stability and safety of LMBs. However, exposure to air forms Li2CO3 on oxide SSE particles, diminishing their ion flux regulation at the electrode/electrolyte interface. Utilizing the reaction of Li2CO3 with polyacrylic acid (PAA) to form lithium polyacrylate (LiPAA), an ultra-thin composite coating on polyethylene (PE) separator with Li2CO3-free Li6.4La3Zr1.4Ta0.6O12 (LLZTO) particles and LiPAA binder is fabricated in one step. The exposed Li2CO3-free LLZTO surface increases the ionic conductivity and lithium ion (Li+) transference number of the functional separator, resulting in small resistance and uniform Li deposition of the Li metal anode. Consequently, the Li//LiCoO2 cell with the functional separator exhibits a significantly improved life of 980 cycles with 80.9% capacity retention under lean-electrolyte conditions. Both the Li//LiCoO2 coin cell and pouch cell using thin Li foil anode demonstrate good cycling stability and high mechanical robustness. This study provides a green and scalable approach for fabricating advanced separators for LMBs.

Natural Polyphenol‐Reinforced Ion‐Selective Separators for High‐Performance Lithium‐Sulfur Batteries with High Sulfur Loading and Lean Electrolyte

Ion‐selective separators are promising to inhibit soluble intermediates shuttle in practical lithium‐sulfur (Li‐S) batteries. However, designing and fabricating such high‐performance ion‐selective separators using cost‐effective, eco‐friendly, and versatile methods remains a formidable challenge. Here we present ion‐selective separators fabricated via the spontaneous deposition of green tea‐derived polyphenols onto a polypropylene separator, aimed at enhancing the stability of Li‐S batteries. The resulting natural polyphenol‐reinforced ion‐selective (NPRIS24) separators exhibit rapid Li ion transport and high soluble intermediates inhibition capability with an ultralow shuttle rate of 0.67% for Li2S4, 0.19% for Li2S6 and 0.10% for Li2S8. This superior ion‐selectivity arises from the high electronegativity and strong lithiophilic nature of the phenolic compounds. Consequently, we have achieved high‐performance Li‐S batteries that are steadily cyclable under the challenging conditions of an S loading of 5.7 mg cm−2, an electrolyte‐to‐S ratio of 5.1 μL mg−1, and a 50 μm Li foil anode. Furthermore, the NPRIS24 separator enhances the performance of other Li metal batteries utilizing commercial LiFePO4 (5.3 mg cm−2) and LiNi0.5Co0.2Mn0.3O2 (9.9 mg cm−2) cathodes. This work underscores the potential of utilizing natural polyphenols for the design of advanced ion‐selective separators in energy storage systems.

Natural Polyphenol-Reinforced Ion-Selective Separators for High-Performance Lithium-Sulfur Batteries with High Sulfur Loading and Lean Electrolyte.

Ion-selective separators are promising to inhibit soluble intermediates shuttle in practical lithium-sulfur (Li-S) batteries. However, designing and fabricating such high-performance ion-selective separators using cost-effective, eco-friendly, and versatile methods remains a formidable challenge. Here we present ion-selective separators fabricated via the spontaneous deposition of green tea-derived polyphenols onto a polypropylene separator, aimed at enhancing the stability of Li-S batteries. The resulting natural polyphenol-reinforced ion-selective (NPRIS24) separators exhibit rapid Li ion transport and high soluble intermediates inhibition capability with an ultralow shuttle rate of 0.67% for Li2S4, 0.19% for Li2S6 and 0.10% for Li2S8. This superior ion-selectivity arises from the high electronegativity and strong lithiophilic nature of the phenolic compounds. Consequently, we have achieved high-performance Li-S batteries that are steadily cyclable under the challenging conditions of an S loading of 5.7 mg cm-2, an electrolyte-to-S ratio of 5.1 μL mg-1, and a 50 μm Li foil anode. Furthermore, the NPRIS24 separator enhances the performance of other Li metal batteries utilizing commercial LiFePO4 (5.3 mg cm-2) and LiNi0.5Co0.2Mn0.3O2 (9.9 mg cm-2) cathodes. This work underscores the potential of utilizing natural polyphenols for the design of advanced ion-selective separators in energy storage systems.

Design Double Layered Anode for Stably Introducing Lithium Source to Achieve Sulfur‐Carbon Full Batteries

AbstractLithium‐sulfur batteries offer high energy density but face great safety and cycle life challenges due to the use of Li metal anode. Replacing the Li metal anode with pre‐lithiated carbon anodes can thoroughly address cycling stability and safety issues. Directly contacting Li foil with graphite electrode is one of the most efficient and simple strategy to introduce a high content of lithium source into the sulfur‐carbon full batteries. However, the 100% lithiation of the graphite anode through the direct contact method generates excessive heat and stress heterogeneity, which leads to electrode structure cracking and electrochemical properties fading. This study implements a double‐layer anode to mitigate these issues. A thin layer of hard carbon placed between graphite and Cu foil limits heat generation and stress heterogeneity due to its structural and electrochemical stability. Additionally, differing from traditional electrochemical lithiation, this method gains better solid electrolyte interphase (SEI) for the graphite anode after several cycles. This research highlights the mass production potential of coupling high energy density lithium source‐free cathode materials with various lithium source‐free anodes for constructing long‐cycle and high‐safety rechargeable batteries.

A covalently bonded, LiF-rich solid electrolyte interphase for Li metal batteries with superior low-temperature performance

The solid electrolyte interphase (SEI) layer plays a critical role in determining the performance of lithium metal batteries (LMBs). Here, we show that treating Li foils with 4,4,5,5,5-pentafluoropentanol (PFPO) results in the formation of a novel LiF-rich organic/inorganic SEI layer (designated as LiF-PO) that enhances the performance of LMBs. Compared to the native SEI layer that is electrochemically formed in LMBs, the LiF-PO SEI layer is mechanically robust, adopts a compact structure, and exhibits high Li+ conductivity. These features enable Li//Li symmetric cells to exhibit superior performance metrics, even at low temperatures, including inhibited Li dendrite growth, reduced polarization voltage, and elongated cycling lifetime. Moreover, compared to lithium–sulfur cells prepared using bare Li foils, the cells prepared using PFPO-treated Li foils also exhibit markedly improved performance at low temperatures in terms of specific capacity (796 mA h g−1 vs. 559 mA h g−1 at 0.1 C and −20 °C), rate capability (519 mA h g−1 vs. 222 mA h g−1 at 3 C and 0 °C), and cycling stability (504 mA h g−1 vs. 253 mA h g−1 at 0.1 C after 100 cycles at −20 °C). The lessons learned from our study establish new principles for designing high-performance SEI layers and may be extended to other types of metal batteries.

Demonstration of MAX phases as triple functional artificial solid electrolyte interphase for ultralong life lithium metal anodes

Solid electrolyte interphase (SEI) has significant role in controlling lithium (Li) dendrites. However, lack of chemical stability, mechanical strength and self-perfection for conventional SEI cannot persistently suppress Li dendrites, leading to inferior cycling life. Herein, MAX phases (Ti2SnC and Ti2SC) as triple functional artificial SEI (ASEI) with high modulus, chemical stability and self-smoothing ability are introduced on Li foils (Ti2SnC@Li and Ti2SC@Li) for ultralong life Li metal anodes (LMAs). The high mechanical strength with lithiophilicity of the MAX can induce uniform Li deposition and suppress dendrite growth, while the excellent chemical stability and self-smoothing ability of the MAX guarantee the consistency of the ASEI, achieving ultralong life of the LMAs. As a result, the Ti2SnC@Li||Li@Ti2SnC half-cells demonstrate ultralong cycling performance of 5000 h at 5 mAh cm−2 and 5 mA cm−2. The Ti2SnC@Li||LiFePO4(LFP) full-cells demonstrate ultralong stability up to 3000 cycles at 5C. At harsh conditions including 24.3 mg cm−2 of LFP, 6.0 g (Ah)−1 of electrolyte and 2.6 of negative/positive ratio, the Ti2SnC@Li||LFP full-cells maintain 2.9 mAh cm−2 after 130 cycles at 0.3C. This work demonstrates the MAX phases with high modulus, chemical stability and self-smoothing ability as triple functional ASEI for metal anode protection.

Designing Isocyanate‐Containing Elastomeric Electrolytes for Antioxidative Interphases in 4.7 V Solid‐State Lithium Metal Batteries

AbstractTo facilitate the use of solid polymer electrolytes (SPEs) with high‐nickel (Ni) cathodes in high‐voltage lithium (Li) metal batteries (LMBs), it is crucial to address the challenges of low oxidative stability and the formation of vulnerable interphases. In this study, isocyanate groups (−N═C═O) are incorporated to develop an SPE with a bi‐continuous structure, consisting of elastomeric and plastic crystal phases. This rationally designed SPE exhibits high ionic conductivity (0.9 × 10−3 S cm−1 at 25 °C), excellent elasticity (elongation at break of 330%), and enhanced oxidative stability (over 4.8 V vs. Li/Li⁺). A full cell, incorporating this SPE with a thin Li foil of 40 µm, and a high‐Ni LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode operating at 4.7 V vs. Li/Li⁺, demonstrates excellent cyclability, retaining 70% of its initial capacity after 200 cycles under a high C‐rate of 1C at 25 °C. The extended cycling of isocyanate‐containing SPE at 4.7 V vs. Li/Li⁺ is attributed to robust and compact inorganic‐rich interphases enabled by antioxidative −N−C═O components, as well as uniform Li deposition attributed to the bi‐continuous structured SPE. This study suggests that the isocyanate‐containing SPE system is a promising candidate for high‐voltage solid‐state LMBs by constructing stable interphases.

An In Situ Generated Organic/Inorganic Hybrid SEI Layer Enables Li Metal Anodes with Dendrite Suppression Ability, High-Rate Capability, and Long-Life Stability.

High-quality solid electrolyte interphase (SEI) layers can effectively suppress the growth of Li dendrites and improve the cycling stability of lithium metal batteries. Herein, 1-(6-bromohexanoyl)-3-butylurea is used to construct an organic/inorganic hybrid (designated as LiBr-HBU) SEI layer that features a uniform and compact structure. The LiBr-HBU SEI layer exhibits superior electrolyte wettability and air stability as well as strong attachment to Li foils. The LiBr-HBU SEI layer achieves a Li+ conductivity of 2.75 × 10-4 S cm-1, which is ≈50-fold higher than the value measured for a native SEI layer. A Li//Li symmetric cell containing the LiBr-HBU SEI layer exhibits markedly improved cyclability when compared with the cell containing a native SEI layer, especially at a high current density (e.g., cycling life up to 1333h at 15mA cm-2). The LiBr-HBU SEI layer also improves the performance of lithium-sulfur cells, particularly the rate capability (548 mAh g-1 at 10C) and cycling stability (513 mAh g-1 at 0.5C after 500 cycles). The methodology described can be extended to the commercial processing of Li metal anodes as the artificial SEI layer also protects Li metal against corrosion.

In-situ analysis of cathode and anode impedances to probe the performance degradation of lithium–sulfur batteries

Improving the performance of Li-metal batteries with sulfur cathodes while maintaining high sulfur loading (>4 mg cm−2) and low electrolyte-to-sulfur ratio (<10 mg μL−1) is a significant challenge. These conditions often result in poor battery cycle life and sudden capacity failure during charge-discharge processes. To address this challenge, we investigate Li–S batteries in a three-electrode (3E) configuration, utilizing optimized materials and geometries for the reference electrode. This configuration allows us to independently track the in-situ variations in cathode and anode resistances, along with the electrode potential difference, unveiling the root causes of abrupt battery failure during cycling. Our 3E approach uncovers previously unnoticed distortion phenomena in the electrochemical impedance spectra of both the cathode and anode, providing essential indicators of imminent micro-short circuiting. Supported by simulations using the finite element method and equivalent circuit analysis software, these insights clarify that the primary reason for battery failure is the growth of Li dendrites and their subsequent contact with the cathode, rather than a sudden increase in cell impedance. By substituting traditional Li foil with a specially designed Li anode less susceptible to Li dendrite growth, we achieve reduced anode resistance and improved battery capacity and cycle life stability. This research reveals the potential of the 3E configuration for precise in-situ impedance monitoring, which is valuable for devising strategies to enhance cycle stability.

2D Metal-Oxide Nanosheets as a Homogeneous Li-Ion Flux Regulator for High-Performance Anodeless Lithium Metal Batteries.

The anodeless battery design has recently gained significant interest by eliminating the direct use of a thick lithium (Li) foil. However, it suffers from inhomogeneous Li+ flux, resulting in dendrite growth and a short cycling life. To address this, the exfoliation of layered-structure titanium oxide to 2D nanosheets (2DTiOx) is proposed to precisely control Li+ flux at the atomic scale by maximizing Li+ affinitive Ti sites. Compared to cells without these nanosheets, the Li|2DTiOx|Cu half-cell demonstrates stable cyclability over 900 cycles, with a Coulombic efficiency (CE) over 99% at 0.5 mA cm-2 and 0.5 mAh cm-2. Similarly, a long stable cycling life over 1500 h at 1.0-3.0 mA cm-2 is observed for a 2DTiOx-based symmetric cell containing a limited Li amount from electrodeposited Li metal (e-Li|2DTiOx|e-Li). The full cells (e-Li|2DTiOx||NCM811 and e-Li|2DTiOx||LFP) coupled with NCM811 and LFP cathodes showed a long cycle life of 400 cycles at 1.0 C and 0.5 C, respectively. The exceptional battery performance is attributed to the uniform Li disposition on the 2DTiOx electrode, emphasizing the crucial role of the exposed basal plane in 2DTiOx as an efficient atomic scale Li+ flux regulator. This strategy is expected to advance next-generation lithium metal batteries (LMBs) by highlighting the significance of Li+ affinity at the Ti sites of 2DTiOx nanosheets.

Stable Anode-Free All-Solid-State Lithium Battery through Tuned Metal Wetting on the Copper Current Collector

Stable anode-free all-solid-state battery (AF-ASSB) with sulfide-based solid-electrolyte (SE) (argyrodite Li6PS5Cl, LPSCl) is achieved by tuning wetting of lithium metal on “empty” copper current-collector. Lithiophilic 1 μm Li2Te is synthesized by exposing the collector to tellurium vapor, followed by in-situ Li activation during the first charge. The Li2Te significantly reduces the electrodeposition/electrodissolution overpotentials and improves Coulombic efficiency (CE). During continuous plating experiments using half-cells (1 mA cm-2), the accumulated thickness of electrodeposited Li on Li2Te-Cu is more than 70 μm, which is the thickness of Li foil counter-electrode. Full AF-ASSB with NMC811 cathode delivers an initial CE of 83% at 0.2C, with a cycling CE above 99%. Cryo-FIB sectioning demonstrates uniform electrodeposited metal microstructure, with no signs of voids or dendrites at the collector-SE interface. Electrodissolution is uniform and complete, with Li2Te remaining structurally stable and adherent. By contrast, unmodified Cu current-collector promotes inhomogeneous Li electrodeposition/electrodissolution, electrochemically inactive “dead metal”, dendrites that extend into SE, and thick non-uniform solid electrolyte interphase (SEI) interspersed with pores. Density functional theory and mesoscale calculations provide complementary insight regarding nucleation-growth behavior. Unlike for conventional liquid-electrolyte metal batteries, the role of current collector/support lithiophilicy has not been explored for emerging AF-ASSBs.

(Invited) A Facile Three-Dimensional Lightweight Current Collector Strategy for High Energy Density Lithium Metal Batteries

Despite the great achievement in the development of rechargeable lithium (Li) metal batteries (LMBs) with high energy densities, their practical application is still facing difficulties due to the intrinsic issues of Li metal anode (LMA) including high reactivity and dendritic Li formation which cause low Coulombic efficiency, constant loss of Li and electrolyte, and unstable solid electrolyte interphase (SEI) layer, etc. Additionally, from the structural point of view, LMA which consists of Li foil on the two-dimensional copper (Cu) current collector brings the formidable loss of the areal capacity that leads to less specific energy density since Cu is non-faradaic and one of the heavy metals. Further, the “hostless” feature of LMA induces more issues like volume expansion and limited utilization of Li. To address such issues, a metal-coated polymeric three-dimensional (3D) scaffold is designed here. In this study, Cu is selected as an electronic conductivity provider, and electrospun polyimide (PI) is chosen as a 3D scaffold because of its high thermal stability and good mechanical properties. Cu-coated PI (Cu@PI) was produced via a facile electroless process. Driven by the structural/material uniqueness, the developed 3D Cu@PI current collector enables a uniform/continuous Li-ion conduction pathway thus leading to dense Li deposition and enhancing the electrochemical performance of LMBs containing the electrochemically deposited Li on Cu@PI and the specific energy density due to the great reduction in substrate weight. We anticipate the suggested new strategy of 3D structured LMAs would lead to a facile route toward the high energy density LMBs beyond the conventional technologies.

Si3N4 as an Alternative of Silicon for the Anode Application in All‐Solid‐State Li‐Ion Batteries

ABSTRACTThe intermittent nature of renewable energy generation can be tackled by integrating them with electrochemical energy storage, which can also close the gap between supply and demand effectively. It has recently been demonstrated that Si3N4‐based negative electrodes are a promising option for lithium‐ion batteries due to their large theoretical capacity and appropriate working potential with extremely low polarization. In the present work, Si3N4 was utilized as anode material in all‐solid‐state lithium‐ion battery with lithium borohydride as a solid electrolyte and Li foil placed as a counter electrode. The electrochemical properties were investigated using galvanostatic charge/discharge profiling whereas the mechanism of lithiation delithiation was investigated in detail using x‐ray diffraction (XRD). The highest capacity of the composite materials was obtained as 1700 mAhg−1 at 0.05 C current rate in the first cycle, which is reduced to 370 in 5 cycles. However, a stability in the capacity was observed in subsequent cycles and a retention of almost 88% could be achieved in 150 cycles. The interfacial resistance before and after the electrochemical cycling was observed as 326 Ω and 13 kΩ, respectively which is also supported by the microstructural investigations where the cracks are observed because of thermochemical reactions.

Designing a Stable Alloy Interlayer on Li Metal Anodes for Fast Charging of All-Solid-State Li Metal Batteries

The deposition of a thin LixSny alloy layer by plasma vapor deposition (PVD) on the surface of a Li foil is reported. The formation of a Li-rich alloy is confirmed by the volume expansion (up to 380%) of the layer and by the disappearance of metallic Sn peaks in the X-ray diffractogram. The layer has a much higher hardness than bare Li and can withstand aggressive cycling at 1C. Post-mortem scanning electron microscope observations revealed that the alloy layer remains intact even after fast cycling for hundreds of cycles. A concept of double modification by adding a thin ceramic/polymer layer deposited by a doctor blade on top of the LixSny layer was also reported to be efficient to reach long-term stability for 500 cycles at C/3. Finally, a post-treatment after Sn deposition consisting of a plasma cleaning of the LixSny alloy layer led to a strong improvement in the cycling performance at 1C. The surface is smoother and less oxidized after this treatment. The combination of a Li-rich alloy interlayer, the increase in hardness at the electrolyte/Li interface, and the absence of dissolution of the layer during cycling at high C-rates are reasons for such an improvement in electrochemical performance.

A compact lithiophilic dual metal oxide nanowire array on 3D copper mesh enables dendrite-free long-life lithium metal anodes

Lithium metal anodes (LMAs) are the prospective candidates for the future energy storage/conversion systems because of high theoretical capacity and the lowest negative potential. However, the instability of solid electrolyte interphase and the generation of lithium dendrites during the repeated plating/striping process have become the serious challenges for commercialization of LMAs. Herein, a composite anode is obtained by simply pressing three dimensional CuO@MnO2-modified copper mesh (3D CMCM) into Li foil, and named as 3D CMCM/Li. The lithiophilic 3D CMCM not only possesses a low nucleation overpotential but also ensures the uniform deposition of Li. Density functional theory (DFT) calculations also confirm the lithiophilic essence of both CuO and MnO2. Meanwhile, the 3D CMCM skeleton with nanowire arrays makes contributions to reducing the local current density and enhancing Li plating/stripping reversibility. Significantly, owing to the synergistic effect of lithiophilic CuO@MnO2 and unique 3D copper skeleton structure with nanowire arrays, the half-cell composed of 3D CMCM exhibits a satisfactory Coulombic efficiency (CE, 99.6 %) and the cycle life (300 cycles) at 1 mAh cm−2. And the symmetric cell with 3D CMCM/Li exhibits a low voltage hysteresis and a long cycle stability of 3100 h at 1 mA cm−2/1 mAh cm−2. Moreover, the full cells assembled with sulfur-nitrogen, sulfur, and phosphorus co-doped carbon (S-NSPC) and LiFePO4 (LFP) cathodes possess the good cycling and rate performance. It is worth noting that the 3D CMCM/Li composite anode designed in this work offers an additional inspiration for the development of LMAs in the future.

Capacity Degradation of Zero-Excess All-Solid-State Li Metal Batteries Using a Poly(ethylene oxide) Based Solid Electrolyte.

Solid-state polymer electrolytes (SPEs), such as poly(ethylene oxide) (PEO), have good flexibility when compared to ceramic-type solid electrolytes. Therefore, it could be an ideal solid electrolyte for zero-excess all-solid-state Li metal battery (ZESSLB), also known as anode-free all-solid-state Li battery, development by offering better contact to the Cu current collector. However, the low Coulombic efficiencies observed from polymer type solid-state Li batteries (SSLBs) raise the concern that PEO may consume the limited amount of Li in ZESSLB to fail the system. Here, we designed ZESSLBs by using all-ceramic half-cells and an extra PEO electrolyte interlayer to study the reactivity between PEO and freshly deposited Li under a real battery operating conduction. By shuttling active Li back from the anode to the cathode, the PEO SPEs can be separated from the ZESSLBs for experimental studies without the influence from cathode materials or possible contamination from the usage of Li foil as the anode. Electrochemical cycling of ZESSLBs shows that the capacities of ZESSLBs with solvent-free and solvent-casted PEO SPEs significantly degraded compared to the ones with Li metal as the anode for the all-solid-state Li batteries. The fast capacity degradation of ZESSLBs using different types of PEO SPEs is evidenced to be associated with Li reacting with PEO, residual solvent, and water in PEO and dead Li formation upon the presence or absence of residual solvent. The results suggest that avoiding direct contact between the PEO electrolyte and deposited lithium is necessary when there is only a limited amount of Li available in ZESSLBs.

Li (200) with in-situ generated high entropy alloy/oxide fillers and Li2O enabling desirable Li metal anode

The development of Li metal batteries (LMBs) with high-energy density is impeded by the uncontrollable growth of Li dendrites. In this work, the Li foil is cold-pressed with ball-milled high entropy Mg/Ni/Co/Cu/Zn-based oxides (HEO), which can in-situ generate high entropy alloy/oxide and Li2O in the bulk phase and surface of composited Li anode (denoted as HEA/O@Li). During the cold-pressing process, the Li foil with polycrystalline nature transform into (200) textured Li. The in-situ generated Li2O can provide more lithiophilic sites and enrich the inorganic components of solid state interface (SEI), while the HEA/O fillers dispersed in the composited Li anode can strength corresponding mechanical stability and tune the Li+ stripping/plating process. As a result, the HEA/O@Li exhibits outstanding cycle stability for almost 1000 h at 1 mA cm−2 with fixed area capacity of 1 mAh cm−2. Moreover, the full batteries matched with LiFePO4 cathode demonstrate favorable cycling stability (110 mAh g−1 at 0.5C after 700 cycles) and rate capability.

Sustainable Prelithiation Strategy: Enhancing Energy Density and Lifespan with Ultrathin Li‐Mg‐Al Alloy Foil

AbstractPrelithiation is a well‐established strategy for enhancing battery energy density. However, traditional prelithiation approaches have primarily addressed compensating for the initial active lithium loss (ALL) while overlooking the ALL during extended cycling. In response, a novel method is introduced by increasing the prelithiation degree and pre‐storing stable LiCx within the anode. This innovation facilitates sustainable lithium replenishment, resulting in a significant improvement in battery cycle life and energy density. Moreover, challenges associated with using pure Li foils to realize this strategy in contact prelithiation are revealed, such as difficulties in thinning to less than 5 µm, and the loss of the electronic pathway during prelithiation, resulting in low lithium utilization rates and numerous residues. Additionally, the significantly accelerated capacity fading caused by these residues, typically emerging after hundreds of cycles, has been overlooked. To overcome these challenges, an ultrathin Li‐Mg‐Al alloy foil is developed with significantly improved mechanical properties and delithiation behavior. During prelithiation, the 96Li2Mg2Al alloy maintains a complete film structure with numerous micropores, avoiding randomly distributed debris. This structure ensures high utilization, unimpeded electronic pathways, and efficient electrolyte filtration. By employing a 5‐µm 96Li2Mg2Al foil for sustainable prelithiation, a substantial improvement in energy density is achieved and tripled the battery's lifespan.

Vacuum Evaporation Plating Enabling ≤ 10µm Ultrathin Lithium Foils for Lithium Metal Batteries.

Lithium (Li) metal is widely recognized as a viable candidate for anode material in future battery technologies due to its exceptional energy density. Nevertheless, the commercial Li foils in common use are too thick (≈100µm), resulting in a waste of Li resources. Herein, by applying the vacuum evaporation plating technology, the ultra-thin Li foils (VELi) with high purity, strong adhesion, and thickness of less than 10µm are successfully prepared. The manipulation of evaporation temperature allows for convenient regulation of the thickness of the fabricated Li film. This physical thinning method allows for fast, continuous, and highly accurate mass production. With a current density of 0.5mAcm-2 for a plating amount of 0.5mAhcm-2, VELi||VELi cells can stably cycle for 200h. The maximum utilization of Li is already more than 25%. Furthermore, LiFePO4||VELi full cells present excellent cycling performance at 1C (1C = 155mAhg-1) with a capacity retention rate of 90.56% after 240 cycles. VELi increases the utilization of active Li and significantly reduces the cost of Li usage while ensuring anode cycling and multiplication performance. Vacuum evaporation plating technology provides a feasible strategy for the practical application of ultra-thin Li anodes.