Grafting of Lithiophilic and Electron-Blocking Interlayer for Garnet-Based Solid-State Li Metal Batteries via One-Step Anhydrous Poly-Phosphoric Acid Post-Treatment

Garnet-based solid-state Li-metal batteries (GSSBs) have the merits of high energy density and high safety. However, the realization of a stable and well-matched Li|garnet interface for GSSBs remains challenging due to electron leakage and lithiophobic Li₂CO₃ impurity. To address these issues, herein, new surface chemistry is reported that converts the undesired Li₂CO₃ contaminant into an ultra-thin lithium polyphosphate (Li-PPA) layer through anhydrous polyphosphoric acid -induced in situ substitution reaction without damaging the water-sensitive garnet electrolyte. In particular, the Li-PPA interlayer not only facilitates the homogenous spreading of molten Li but also creates a robust electron-blocking shield to suppress Li dendrite formation. As a result, the assembled Li symmetric cell exhibits a low interfacial impedance (4 Ω cm²) and high critical current density (1.8 mA cm⁻²) at 25 °C, which enables the cell to continuously cycle over 2500 h at 0.2 mA cm⁻². Furthermore, the GSSBs paired with LiFePO₄ deliver a high capacity of 149.3 mAh g⁻¹ at 1 C and maintain 92.3% of the initial capacity after 500 cycles and can be used for solar energy storage, suggesting the feasibility of this interfacial engineering strategy for GSSBs.     

From Contaminated to Highly Lithiated Interfaces: A Versatile Modification Strategy for Garnet Solid Electrolytes

The surface chemistry of garnet electrolyte is sensitive to air exposure. The poor LLZO/Li interface caused by Li₂CO₃/LiOH contaminants on garnet electrolyte surface easily induces large interfacial resistance resulting in the growth of Li dendrites. Herein, a versatile modification strategy is designed to convert the contaminants on Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO) surface into a LiF and Li₂PO₃F-rich lithiophilic interface by targeted chemical reactions at the interface between LiPO₂F₂ and Li₂CO₃/LiOH. The newly formed LiF-Li₂PO₃F interfacial layer not only facilitates the interface wettability between Li and LLZTO, but also helps to resist corrosion of the LLZTO surface by moisture in the air. The Li|LiF&Li₂PO₃F-LLZTO|Li symmetric cell exhibits a low interfacial resistance of 5.1 Ω cm² and ultrastable galvanostatic cycling, over 1500 h at 0.6 mA cm⁻² and over 70 h at 1.0 mA cm⁻². In addition, LiCoO₂|LiF&Li₂PO₃F-LLZTO|Li hybrid solid-state full cells display high initial specific capacity of 192 mAh g⁻¹ at 0.1 C, and excellent cycling stability with a capacity retention over 76% even after 1000 cycles at 0.5 C at a high cut-off voltage of 4.5 V. This study provides a simple and practical strategy for the feasibility of the application of high-voltage cathodes in this modified garnet all-solid-state batteries.     

Alloyable Viscous Fluid for Interface Welding of Garnet Electrolyte to Enable Highly Reversible Fluoride Conversion Solid State Batteries

The garnet-type solid-state Li-metal batteries are promising to develop into the high-energy-density system when coupled with the high-capacity conversion reaction cathodes. However, the high interfacial resistance and poor contact between garnet electrolyte and Li anode are still a challenge. Here, an alloyable viscous fluid strategy is proposed for Li/garnet interface welding to enable highly reversible fluoride conversion solid-state batteries. The super-assembled phenide polymer with liquid metal property can serve as “oily” interlayer to in situ construct an ionic/electronic mixed conduction network by thermal and electrochemical lithiation. The resultant healing effect of contact voids between garnet and Li enables a dramatic reduction of interfacial resistance to 6 Ω cm². The confinement and compaction of conversion products by garnet electrolyte endow the FeF₃ based batteries with long-cycling and high-rate performance (520 and 330 mAh g⁻¹ at 0.2 and 2 C respectively). This ceramic configuration also endows the CuF₂ conversion battery with much better rechargeability (instead as widely known primary battery).     

High-Performance Garnet-Type Solid-State Lithium Metal Batteries Enabled by Scalable Elastic and Li+-Conducting Interlayer

Promoting the interfacial Li⁺ transport and suppressing detrimental lithium dendrites are the main challenges for developing practical solid-state lithium metal batteries. In this respect, interface rationalizing to synergize the enhancement of ion transport and suppression of lithium dendrites is of paramount significance. Herein, a novel strategy is demonstrated to address those issues by a designed multifunctional composite interlayer. The photocrosslinkable polymer is introduced in a scalable elastic skeleton, which promotes the migration and diffusion of Li⁺. Moreover, adding perfluoropolyether in the interlayer benefits to regulating the formation of LiF-rich interface, sufficiently suppress the growth of lithium dendrites. Benefitting from the elasticity, high Li⁺ conductivity and the lithium dendrites suppression capability, the interlayer can significantly improve the interfacial performance of the solid electrolyte/lithium interface, thus leading to the greatly enhanced electrochemical performance of solid-state lithium metal batteries. A high critical current density of 3.6 mA cm⁻² and a long cycling life at 1.0 mA cm⁻² for >400 h are achieved for the symmetric cells. Besides, when used in a pouch-type full cell coupled with LiNi_0.6Co_0.2Mn_0.2O₂ cathode, a high charged capacity of 3.25 mAh cm⁻² can be maintained through 20 cycles, demonstrating its great potentials for practical application.     

Hierarchical Composite-Solid-Electrolyte with High Electrochemical Stability and Interfacial Regulation for Boosting Ultra-Stable Lithium Batteries

Solid-state electrolytes have drawn enormous attention to reviving lithium batteries but have also been barricaded in lower ionic conductivity at room temperature, awkward interfacial contact, and severe polarization. Herein, a sort of hierarchical composite solid electrolyte combined with a “polymer-in-separator” matrix and “garnet-at-interface” layer is prepared via a facile process. The commercial polyvinylidene fluoride-based separator is applied as a host for the polymer-based ionic conductor, which concurrently inhibits over-polarization of polymer matrix and elevates high-voltage compatibility versus cathode. Attached on the side, the compact garnet (Li_6.4La₃Zr_1.4Ta_0.6O₁₂) layer is glued to physically inhibit the overgrowth of lithium dendrite and regulate the interfacial electrochemistry. At 25 °C, the electrolyte exhibits a high ionic conductivity of 2.73 × 10⁻⁴ S cm⁻¹ and a decent electrochemical window of 4.77 V. Benefiting from this elaborate electrolyte, the symmetrical Li||Li battery achieves steady lithium plating/stripping more than 4800 h at 0.5 mA cm⁻² without dendrites and short-circuit. The solid-state batteries deliver preferable capacity output with outstanding cycling stability (95.2% capacity retained after 500 cycles, 79.0% after 1000 cycles at 1 C) at ambient temperature. This hierarchical structure design of electrolyte may reveal great potentials for future development in fields of solid-state metal batteries.     

Dendrite-Free Lithium Metal Batteries Enabled by Coordination Chemistry in Polymer-Ceramic Modified Separators

Issues with lithium dendrite growth and dead lithium formation limit the practical application of lithium metal batteries, especially under high current conditions where uneven temperature distribution leads to serious safety concerns. Herein, In situ assembly of polydopamine (PDA) and aluminum nitride (AlN) coatings on polypropylene (PP) separator is introduced to address these challenges. The AlN particles are encapsulated by PDA, and the functional groups in PDA form Al-O coordination bonds with Al³⁺, which promote uniform Li⁺ flux and reduce the migration barrier of Li⁺, thereby enabling dendrite-free lithium deposition. In addition, the designed PDA@AlN@PP separator exhibits excellent electrolyte wettability, enhanced mechanical performance, and stable thermal resistance, providing a uniform thermal distribution and serving as a robust barrier against dendrite penetration. As a result, symmetric Li||Li cells (over 1800 h at 1 mA cm⁻² and 1 mAh cm⁻²) and Li||Cu cells (over 600 cycles at 0.5 mA cm⁻² and 0.5 mAh cm⁻², coulombic efficiency over 98%) demonstrate outstanding long cycle performance and high coulombic efficiency. Moreover, the corresponding Li||LiFePO₄ cells exhibit a high specific capacity of 91.3 mAh g⁻¹ at 5 C. This work provides a new approach for designing functionalized separators for high-performance lithium metal batteries.     

Hexafluoroisopropyl Trifluoromethanesulfonate-Driven Easily Li+ Desolvated Electrolyte to Afford Li||NCM811 Cells with Efficient Anode/Cathode Electrolyte Interphases

Solid electrolyte interphase (SEI) and cathode electrolyte interphase (CEI) with optimized components and structures are considered to be crucial for lithium-ion batteries. Here, gradient lithium oxysulfide (Li₂SO_x, x = 0, 3, 4)/uniform lithium fluoride (LiF)-type SEI is designed in situ by using hexafluoroisopropyl trifluoromethanesulfonate (HFPTf) as electrolyte additive. HFPTf is more likely to be reduced on the surface of Li anode in electrolytes due to its high reduction potential. Moreover, HFPTf can make Li⁺ desolvated easily, leading to the increase in the flux of Li⁺ on the surface of Li anode to avoid the growth of Li dendrites. Thus, the cycling stability of Li||Li symmetric cells is improved to be 1000 h at 0.5 mA cm⁻². In addition, HFPTf-contained electrolyte could make Li||NCM811 batteries with a capacity retention of 70% after 150 cycles at 100 mA g⁻¹, which is attributed to the formation of uniform and stable CEI on the cathode surface for hindering the dissolvation of metal ions from the cathode. This study provides effective insights on the strong ability of additives to adjust electrolytes in “one phase and two interphases” (electrolyte and SEI/CEI).     

Smart Construction of an Intimate Lithium | Garnet Interface for All-Solid-State Batteries by Tuning the Tension of Molten Lithium

All-solid-state lithium batteries (ASSBs) have the potential to trigger a battery revolution for electric vehicles due to their advantages in safety and energy density. Screening of various possible solid electrolytes for ASSBs has revealed that garnet electrolytes are promising due to their high ionic conductivity and superior (electro)chemical stabilities. However, a major challenge of garnet electrolytes is poor contact with Li-metal anodes, resulting in an extremely large interfacial impedance and severe Li dendrite propagation. Herein, an innovative surface tension modification method is proposed to create an intimate Li | garnet interface by tuning molten Li with a trace amount of Si₃N₄ (1 wt%). The resultant Li-Si-N melt can not only convert the Li | garnet interface from point-to-point contact to consecutive face-to-face contact but also homogenize the electric-field distribution during the Li stripping/depositing process, thereby significantly decreasing its interfacial impedance (1 Ω cm² at 25 °C) and improving its cycle stability (1000 h at 0.4 mA cm⁻²) and critical current density (1.8 mA cm⁻²). Specifically, the all-solid-state full cell paired with a LiFePO₄ cathode delivered a high capacity of 145 mAh g⁻¹ at 2 C and maintained 97% of the initial capacity after 100 cycles at 1 C.     

Superionic Conductor Enabled Composite Lithium with High Ionic Conductivity and Interfacial Wettability for Solid-State Lithium Batteries

The urgent demand for high energy and safety batteries has generated the rapid development of Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO) type solid-state lithium metal batteries. However, severe dendritic lithium growth, which is caused by poor interfacial contact of the Li/LLZTO interface and loss of electrical contact during cycles due to low intrinsic Li⁺ diffusion coefficient of lithium, greatly hampers its practical application. Here, from the point of view of reducing surface tension and improving ion diffusion of lithium, a composite lithium anode (CLA) with high wettability and ion diffusion coefficient is prepared by adding GaP into molten lithium, thus strengthening the CLA/LLZTO interface even in cycling. As envisioned, compared to pure lithium, CLA presents lower surface tension, larger adhesion work, and higher ion diffusion coefficient, ensuring close contact of the CLA/LLZTO interface. Therefore, the assembled symmetric cells exhibit a low area specific resistance of 4.5 Ω cm², a large critical current density of 2.5 mA cm⁻², and ultra-long lifespan of 5700 h at 0.3 mA cm⁻² at 25 °C. Meanwhile, full cells coupled with LiFePO₄ cathode show a high-capacity retention of 97.32% after 490 cycles at 1C. This work provides a new solution to the interfacial challenges of solid-state lithium-metal batteries.     

Active Regulation Volume Change of Micrometer-Size Li2S Cathode with High Materials Utilization for All-Solid-State Li/S Batteries through an Interfacial Redox Mediator

Low electronic and ionic transport, limited cathode active material utilization, and significant volume change have pledged the practical application of all-solid-state Li/S batteries (ASSLSBs). Herein, an unprecedented Li₂S-Li_xIn₂S₃ cathode is designed whereby In₂S₃ reacts with Li₂S under high-energy ball milling. In situ electron diffraction and ex situ XPS are implanted to probe the reaction mechanism of Li₂S-Li_xIn₂S₃ in ASSLSBs. The results indicate that Li_xIn₂S₃ serves as a mobility mediator for both charge-carriers (Li⁺ and e⁻) and redox mediator for Li₂S activation, ensuring efficient electronic and ionic transportation at the cathode interface and inhibiting ≈ 70% relative volumetric change in the cathode, as confirmed by in situ TEM. Thus, the Li₂S-Li_xIn₂S₃ cathode delivers an initial areal capacity of 3.47 mAh cm⁻² at 4.0 mg_Li2S cm⁻² with 78% utilization of Li₂S. A solid-state cell with Li₂S-Li_xIn₂S₃ cathode carries 82.35% capacity retention over 200 cycles at 0.192 mA cm⁻² and a remarkable rate capability up to 0.64 mA cm⁻² at RT. Besides, Li₂S-Li_xIn₂S₃ exhibits the highest initial areal capacity of 4.08 mAh cm⁻² with ≈74.01% capacity retention over 50 cycles versus 6.6 mg_Li2S cm⁻² at 0.192 mA cm⁻² at RT. The proposed strategy of the redox mediator minimized volumetric change and realized outstanding electrochemical performance for ASSLSBs.     

Superlithiophilic,Ultrastable, and Ionic-Conductive Interface Enabled Long Lifespan All-Solid-State Lithium-Metal Batteries under High Mass Loading

Garnet-type Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO) suffers from instability against moist air, poor interfacial contact with anode, and serious dendrite issue, which greatly impede its practical application in all-solid-state lithium batteries (ASSLBs). Herein, a superlithiophilic, moisture-resistant, and robust interlayer is demonstrated to overcome these obstacles by in situ forming an AlF₃ interlayer on the LLZTO surface. Thanks to the unique property, the AlF₃-modified LLZTO offers a significantly reduced interfacial resistance by more than two orders of magnitude (from 527.5 Ω cm² for the pristine Li/LLZTO to 1.3 Ω cm² for the surface-engineered interface), achieves a critical current density of 1.2 mA cm⁻² and long-term stability of over 4000–4700 h, and endows regulated Li plating/stripping behaviors. Specifically, ASSLBs coupled with LiFePO₄ and LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) cathodes can stably charge/discharge over 400 and 100 cycles at 0.5 and 0.2 C at 25 °C, with retentions of >80.0% and Coulombic efficiencies of >99.9%, respectively. Particularly, the NCM811-based full ASSLB with large mass loading of 8.3 mg cm⁻² also delivers a discharge-specific capacity as high as 199.1 mAh g⁻¹ with good rate capability, even approaching to the liquid cells. This study demonstrates a practical solution to address the interfacial challenges and paves the way for practical progress of ASSLBs.     

A 3D Cross-Linking Lithiophilic and Electronically Insulating Interfacial Engineering for Garnet-Type Solid-State Lithium Batteries

Solid-state batteries (SSBs) promise high energy density and strong safety due to using nonflammable solid-state electrolytes (SSEs) and high-capacity Li metal anode. Ta-substituted Li₇La₃Zr₂O₁₂ (LLZT) SSE possesses superior ionic conductivity and stability with Li metal, yet the interfacial compatibility and lithium dendrite hazards still hinder its applications. Herein, an interfacial engineering is demonstrated by facile acid-salt (AS) treatment on LLZT, constructing a 3D cross-linking LiF-LiCl (CF) network. Such structure facilitates Li wetting via capillary permeation. Notably, CF as electronically insulting phases block the electrons through the interface and ulteriorly suppress the dendrite formation. The assembled Li symmetric cell exhibited a low interfacial impedance (11.6 Ω cm²) and high critical current densities (CCDs) in the time-constant mode, 1.8 mA cm⁻² at 25 °C and 3.6 mA cm⁻² at 60 °C, respectively. Meanwhile, by exploring the capacity-constant mode of CCD measurement, the concept of critical areal capacity (CAC) is first proposed, obtaining its values of ≈0.5 mAh cm⁻² at 25 °C and 1.2 mAh cm⁻² at 60 °C. Moreover, the safety-enhanced hybrid SSBs matched with LiFePO₄ and LiNi_0.6Co_0.2Mn_0.2O₂ deliver a remarkable rate and cycling performances, validating the feasibility of this interfacial engineering in various SSB systems.     

Dendrite-Free Reverse Lithium Deposition Induced by Ion Rectification Layer toward Superior Lithium Metal Batteries

Considerable endeavors are developed to suppress lithium (Li) dendrites and improve the cycling stability of Li metal batteries in order to promote their commercial application. Herein, continuous zinc (Zn) nanoparticles-assembled film with homogenous nanopores is proposed as a modified layer for separator via a scalable method. The in situ formed LiZn alloy film during initial Li plating can serve as a Li⁺ ion rectification and lithiophilic layer to regulate the nucleation and reverse deposition of Li. When applied in Li|LiFePO₄ full cells with traditional carbonate-based electrolyte, the modified separator enables outstanding cycling stability of up to 350 cycles without capacity loss at a large rate of 5 C (3.4 mA cm⁻²) and a remarkable reversible capacity of 144 mAh g⁻¹ after 120 cycles at a commercial mass loading as high as 19.72 mg cm⁻². The excellent electrochemical performances are ascribed to the dendrite-free reverse Li deposition induced by modified layer by means of its lithiophilic property for regulating homogeneous Li nucleation on the separator as well as its well-distributed nanopores for homogenizing Li⁺ ion flux and enhancing electrolyte wetting.     

Inorganic Filler Enhanced Formation of Stable Inorganic-Rich Solid Electrolyte Interphase for High Performance Lithium Metal Batteries

Lithium metal (LM) is a promising anode material for next generation lithium ion based electrochemical energy storage devices. Critical issues of unstable solid electrolyte interphases (SEIs) and dendrite growth however still impede its practical applications. Herein, a composite gel polymer electrolyte (GPE), formed through in situ polymerization of pentaerythritol tetraacrylate with fumed silica fillers, is developed to achieve high performance lithium metal batteries (LMBs). As evidenced theoretically and experimentally, the presence of SiO₂ not only accelerates Li⁺ transport but also regulates Li⁺ solvation sheath structures, thus facilitating fast kinetics and formation of stable LiF-rich interphase and achieving uniform Li depositions to suppress Li dendrite growth. The composite GPE-based Li||Cu half-cells and Li||Li symmetrical cells display high Coulombic efficiency (CE) of 90.3% after 450 cycles and maintain stability over 960 h at 3 mA cm⁻² and 3 mAh cm⁻², respectively. In addition, Li||LiFePO₄ full-cells with a LM anode of limited Li supply of 4 mAh cm⁻² achieve capacity retention of 68.5% after 700 cycles at 0.5 C (1 C = 170 mA g⁻¹). Especially, when further applied in anode-free LMBs, the carbon cloth||LiFePO₄ full-cell exhibits excellent cycling stability with an average CE of 99.94% and capacity retention of 90.3% at the 160th cycle at 0.5 C.     

Composite Lithium Metal Anodes with Lithiophilic and Low-Tortuosity Scaffold Enabling Ultrahigh Currents and Capacities in Carbonate Electrolytes

The practical application of lithium metal anode has been hindered by safety and cyclability issues due to the uncontrollable dendrite growth, especially during fast cycling and deep plating/stripping process. Here, a composite Li metal anode supported by periodic, perpendicular, and lithiophilic TiO₂/poly(vinyl pyrrolidone) (PVP) nanofibers via a facial rolling process is reported. TiO₂/PVP nanofibers with good Li affinity provide low-tortuosity and directly inward Li⁺ transport paths to facilitate Li nucleation and deposition under high areal capacities and current densities. The micrometer-scale interspaces between TiO₂/PVP walls offer enough space to circumvent the huge volume variation and avoid structure collapsing during the repeated deep Li plating/stripping. The unique structure enables stable cycling under ultrahigh currents (12 mA cm⁻²), and ultra-deep plating/stripping up to 60 mAh cm⁻² with a long cycle life in commercial carbonate electrolytes. The gassing behavior in operating pouch cells is observed using ultrasonic transmission mapping. When paired with LiFePO₄ (5 mAh cm⁻²), sulfur (3 mAh cm⁻²), and high-voltage LiNi_0.8Co_0.1Mn_0.1O₂ cathodes, the composite Li anodes deliver remarkably improved rate performance and cycling stability, demonstrating that it could be a promising strategy for balancing high-energy density and high-power density in Li metal batteries.     

Constructing a Multifunctional Interlayer toward Ultra-High Critical Current Density for Garnet-Based Solid-State Lithium Batteries

All-solid-state lithium batteries (ASSLBs), exhibiting great advantages of high energy density and safety, are proposed to be the next generation energy storage system. However, the successful commercialization of garnet-based ASSLBs is hindered by the poor contact between solid-state electrolytes (Li_6.25Ga_0.25La₃Zr₂O₁₂, LGLZO) and lithium anode, as well as low critical current density (CCD). Herein, an indium tin oxide (ITO) layer is prepared on LGLZO by ultrasonic spraying technique, where ITO reacts with molten lithium to form a composite interlayer, consisting of Li₁₃In₃, Li₂O, and LiInSn. Experiments and density functional theory calculations demonstrate that such a unique interlayer plays a multifunctional role in achieving simultaneously better interface wettability, uniform Li deposition, and dendrite suppression at Li/LGLZO interface. Consequently, the CCD of ITO-treated symmetric cell is increased to a record-high value of 12.05 mA cm⁻² at room temperature, which is expected to promote practical application of ASSLBs. Moreover, the Li/ITO@LGLZO/Li cell exhibits a low interfacial resistance of only 5.9 Ω cm² and performs stable electrochemical operations for over 2000 h at 2 mA cm⁻². The Li/ITO@LGLZO/LiFePO₄ full cell also delivers superior electrochemical performances, demonstrating the efficiency of the ITO layer.     

Dendrite-Free Li-Metal Anode Enabled by Dendritic Structure

The practical application of Li-metal anode in high-energy rechargeable Li batteries is still hindered by the uncontrollable formation of Li dendrites. Here, a facile way is reported to stabilize Li-metal anode by building dendrite-like Li₃Mg₇ alloys enriched with Li-containing polymers as the physical protecting layer and LiH as the Li-ion conductor. This unique dendritic structure effectively reduces local current density and accommodates volume change during the repeated Li plating/stripping process. More importantly, lithiophilic Li₃Mg₇ alloys not only guide the uniform Li deposition down into the below Li metal upon Li deposition, but also thermodynamically promote the extraction of Li during the reverse Li stripping process, which suppresses the parasitic reactions occurring on the surface of Li metal and hence inhibits the formation of Li dendrites. Moreover, the facile diffusion of Mg from Li₃Mg₇ alloys toward Li metal below is thermodynamically permitted, which leads to a uniform distribution of LiMg alloys inside the whole electrode and thus benefits long-term deep cycling stability. As a result, the protected Li-metal anode delivers stable and dendrite-free cycling performance at 10 mA h cm⁻² for over 900 h. When coupling this anode with LiFePO₄ and S cathodes, the thus-assembled full cells exhibit superior cycling stability.     

High Performance Li Metal Anode Enabled by Robust Covalent Triazine Framework-Based Protective Layer

Advanced high-energy-density energy storage systems with high safety are desperately demanded to power electric vehicles and smart grids. Li metal batteries (LMBs) can provide a considerable leap in battery energy. Nevertheless, the widespread deployment of Li metal has long been fettered by the unstable solid electrolyte interlayer and uncontrolled Li dendrite growth induced safety concerns. Herein, a flexible and conformal CTF-LiI coating has been rationally coated on Li metal surface to stabilize metallic Li. With the CTF-LiI coating, the Li electrodeposition exhibits a uniform, dense, and dendrite-free manner; however, the side reactions between metallic Li and electrolyte have been effectively suppressed. The Li symmetric cells can run stably for a prolonged cycling over 2500 cycles at 10 mA cm⁻², demonstrating a much lower voltage hysteresis. In addition, the Li|Li₄Ti₅O₁₂ cells can deliver an improved long-time cycling over 250 cycles at 0.05 A g⁻¹. Furthermore, the half cells paired with the organic S cathode also demonstrate an excellent long lifespan stable cycling and a high capacity of 682.2 mAh g⁻¹ retained over 300 cycles with an average capacity decay of ≈0.05% per cycle at 1.0 A g⁻¹. This work demonstrates a significant step toward large-scalable and long-cycling stable LMBs.     

Homogeneous Li+ Flux Distribution Enables Highly Stable and Temperature-Tolerant Lithium Anode

3D carbon hosts can enable low-stress Li metal anodes (LMAs) with improved structural and interfacial stability. However, the uneven Li⁺ flux and large concentration polarization, resulting from intrinsically poor Li affinity and limited porosity of carbon scaffolds, make the precise control of Li plating/stripping still one the key challenges facing advanced LMAs. Here it is demonstrated that a lightweight carbon scaffold, featuring parallel-aligned porous fibers, can work well for homogeneous Li⁺ flux distribution and reduced concentration gradient to form a stable solid electrolyte interphase, and then synergistically guide smooth Li nucleation/growth even at low temperatures. As a result, the obtained LMAs delivers a high areal capacity up to 15 mAh cm⁻², ultralong lifespan (4800 cycles at 4 mA cm⁻²) with very low voltage hysteresis of ≈21 mV, a high practically available specific capacity of 863.9 mAh g⁻¹ after 1000 cycles, and a long-term stable behavior at low-temperature operation. As coupling with the commercial LiNi_1/3Co_1/3Mn_1/3O₂ cathodes and common carbonate-based electrolyte, the corresponding practical cells also possess an ultralong lifespan and outstanding low-temperature functionality. This study not only presents an advanced carbon host candidate but also sheds new light on crucial design principles of carbon scaffolds for practically feasible rechargeable metal batteries.     

Stabilizing Polymer–Lithium Interface in a Rechargeable Solid Battery

Solid polymer electrolytes (SPEs) are promising candidates for developing high‐energy‐density Li metal batteries due to their flexible processability. However, the low mechanical strength as well as the inferior interfacial regulation of ions between SPEs and Li metal anode limit the suppress ion of Li dendrites and destabilize the Li anode. To meet these challenges, interfacial engineering aiming to homogenize the distribution of Li⁺/electron accompanied with enhanced mechanical strength by Mg₃N₂ layer decorating polyethylene oxide is demonstrated. The intermediary Mg₃N₂ in situ transforms to a mixed ion/electron conducting interlayer consisting of a fast ionic conductor Li₃N and a benign electronic conductor Mg metal, which can buffer the Li⁺ concentration gradient and level the nonuniform electric current distribution during cycling, as demonstrated by a COMSOL Multiphysics simulation. These characteristics endow the solid full cell with a dendrite‐free Li anode and enhanced cycling stability and kinetics. The innovative interface design will accelerate the commercial application of high‐energy‐density solid batteries.