Enabling 420 Wh kg-1 Stable Lithium-Metal Pouch Cells by Lanthanum Doping

Wide Temperature 500 Wh kg-1 Lithium Metal Pouch Cells

The performance of lithium metal batteries is significantly affected by temperature variations, which makes it challenging for them to operate across a wide temperature range. Herein, a wide temperature adaption electrolyte is proposed, enabling excellent electrochemical performance of lithium metal batteries from -40 °C to 60 °C. Large, 5.8 Ah pouch cells employing such an electrolyte achieve high energy density of 503.3 Wh kg-1 at 25 °C with a lifespan of 260 cycles and outstanding energy density of 339 Wh kg-1 at -40 °C. The critical role of the solid electrolyte interphase (SEI) in determining the temperature-dependent performance of lithium metal batteries is unveiled. It is demonstrated that the LiF-rich, anion-derived SEI facilitates Li+ diffusion in SEI. Moreover, accelerated Li+ desolvation at SEI is observed. These two aspects promote the kinetics of lithium metal anodes and further inhibit the dendrite growth at low temperatures. This work showcases the importance of understating the chemistry of SEI to enable wide temperature lithium metal batteries.

Robust Nanoscale Anode Protective Layers toward Fast-Charge High-Energy-Density Lithium Metal Batteries

Mechanically stable and structurally homogeneous lithium-electrolyte interfacial layers are crucial in stabilizing lithium (Li) anodes for practical Li metal batteries. Herein, an ultrathin (≈84 nm) and robust artificial protective layer is constructed with reactive two-dimensional (2D) molecular brushes as building blocks. The artificial protective layer can in situ react with underlying Li metal to produce a nanoscale poly(lithium styrenesulfonate)-grafted graphene oxide (GO-g-PSSLi) layer on the outermost surface and an infinite Li-Ag solid solution in the anode. The nanoscale GO-g-PSSLi layer well integrates a large number of single Li-ion conducting PSSLi chains and 2D robust GO backbones, thereby enabling molecular-level homogeneous and fast Li-ion diffusion as well as remarkable mechanical strength. Meanwhile, the simultaneously formed Li-Ag solid solution is beneficial for rapid Li transport in the anode to reduce the Li nucleation barrier and facilitate homogeneous deposition of Li. With such artificial protective layers, a prototype pouch cell with a thin Li metal anode (50 µm) and a high-loading cathode (21.6 mg cm-2) delivers an impressive cycle life of over 350 cycles with 69% capacity retention under harsh conditions. Remarkably, ultrahigh charging power density of 456 W kg-1 and energy density of 325 Wh kg-1 can be simultaneously achieved in an Ah-level pouch cell.

Li2ZnCu3 Modified Cu Current Collector to Regulate Li Deposition

Rationally designing a current collector that can maintain low lithium (Li) porosity and smooth morphology while enduring high-loading Li deposition is crucial for realizing the high energy density of Li metal batteries, but it is still challengeable. Herein, a Li2ZnCu3 alloy-modified Cu foil is reported as a stable current collector to fulfill the stable high-loading Li deposition. Benefiting from the in situ alloying, the generated numerous Li2ZnCu3@Cu heterojunctions induce a homogeneous Li nucleation and dense growth even at an ultrahigh capacity of 12 mAh cm-2. Such a spatial structure endows the overall Li2ZnCu3@Cu electrode with the manipulated steric hindrance and outmost surface electric potential to suppress the side reactions during Li stripping and plating. The resultant Li||Li2ZnCu3@Cu asymmetric cell preserves an ultrahigh average Coulombic efficiency of 99.2 % at 3 mA cm-2/6 mAh cm-2 over 200 cycles. Moreover, the Li-Li2ZnCu3@Cu||LiFePO4 cell maintains a cycling stability of 87.5 % after 300 cycles. After coupling with the LiCoO2 cathode (4 mAh cm-2), the cell exhibits a high energy density of 407.4 Wh kg-1 with remarkable cycling reversibility at an N/P ratio of 3. All these findings present a doable way to realize the high-capacity, dendrite-free, and dense Li deposition for high-performance Li metal batteries.

Macroscopically uniform interface layer with Li+ conductive channels for high-performance Li metal batteries

The numerous grainboundaries solid electrolyte interface, whether naturally occurring or artificially designed, leads to non-uniform Li metal deposition and consequently results in poor full-battery performance. Herein, a lithium-ion selective transport layer is reported to achieve a highly efficient and dendrite-free lithium metal anode. The layer-by-layer assembled protonated carbon nitride nanosheets present uniform macroscopical structure without grainboundaries. The carbon nitride with ordered pores in basal plane provides high-speed lithium-ion transport channels with low tortuosity. Consequently, the assembled 324 Wh kg-1 pouch cell exhibits 300 stable cycles with a capacity retention of 90.0% and an average Coulombic efficiency up to 99.7%. The ultra-dense Li metal anode makes current collector-free anode possible, achieving high energy density and long cycle life of a 7 Ah cell (506 Wh kg-1, 160 cycles). Thus, it is proved that a macroscopically uniform interface layer with lithium-ion conductive channels could achieve Li metal battery with promising application potential.

Super SEI-Forming Anion for Enhanced Interfacial Stability in Solid-State Lithium Metal Batteries

The extremely high chemical reactivity of lithium metal (Li°) electrodes and its enormous volume change during repetitive cycles cause continuous interfacial degradations in prevailing organic electrolytes, thus deteriorating the cycling performances of rechargeable lithium metal batteries (LMBs). Herein, departing from traditional wisdom on the design of electrolyte components, a super SEI-forming anion (SSA), as an efficient percussor for building stable interphases on Li° electrode, is proposed. Comprehensive investigations related to the unique anion chemistry of SSA reveal that the sulfonate and polyfluoroalkyl functionalities synergistically contribute to uniform spatial distributions of designer interfacial species, greatly improving the surface coverage property and conformal ability of the resulting interphases. Consequently, the incorporation of SSA leads to significant improvements in the cyclability of Li° electrode (exceeding 575 mAh cm-2 before failure) and the corresponding rechargeable Li°||LiFePO4 cells [a five-time increase in lifespan as compared to the benchmark cell with the popular SEI-forming anion bis(fluorosulfonyl)imide (FSI)]. The present work offers a paradigm shift to tame the notorious interfacial issues via upgraded anion chemistry, which can promote the practical development of rechargeable LMBs and other kinds of metal batteries.

Enhancing Anion-Selective Catalysis for Stable Lithium Metal Pouch Cells through Charge Separated COF Interlayer

Regulating the composition of solid-electrolyte-interphase (SEI) is the key to construct high-energy density lithium metal batteries. Here we report a selective catalysis anionic decomposition strategy to achieve a lithium fluoride (LiF)-rich SEI for stable lithium metal batteries. To accomplish this, the tris(4-aminophenyl) amine-pyromeletic dianhydride covalent organic frameworks (TP-COF) was adopted as an interlayer on lithium metal anode. The strong donor-acceptor unit structure of TP-COF induces local charge separation, resulting in electron depletion and thus boosting its affinity to FSI-. The strong interaction between TP-COF and FSI- lowers the lowest unoccupied molecular orbital (LUMO) energy level of FSI-, accelerating the decomposition of FSI- and generating a stable LiF-rich SEI. This feature facilitates rapid Li+ transfer and suppresses dendritic Li growth. Notably, we demonstrate a 6.5 Ah LiNi0.8Co0.1Mn0.1O2|TP-COF@Li pouch cell with high energy density (473.4 Wh kg-1) and excellent cycling stability (97.4 %, 95 cycles) under lean electrolyte 1.39 g Ah-1, high areal capacity 5.7 mAh cm-2, and high current density 2.7 mA cm-2. Our selective catalysis strategy opens a promising avenue toward the practical applications of high energy-density rechargeable batteries.

Decreased Electrically and Increased Ionically Conducting Scaffolds for Long-Life, High-Rate and Deep-Capacity Lithium-Metal Anodes

Lithium (Li) metal batteries are deemed as promising next-generation power solutions but are hindered by the uncontrolled dendrite growth and infinite volume change of Li anodes. The extensively studied 3D scaffolds as solutions generally lead to undesired "top-growth" of Li due to their high electrical conductivity and the lack of ion-transporting pathways. Here, by reducing electrical conductivity and increasing the ionic conductivity of the scaffold, the deposition spot of Li to the bottom of the scaffold can be regulated, thus resulting in a safe bottom-up plating mode of the Li and dendrite-free Li deposition. The resulting symmetrical cells with these scaffolds, despite with a limited pre-plated Li capacity of 5 mAh cm-2, exhibit ultra-stable Li plating/stripping for over 1 year (11 000 h) at a high current density of 3 mA cm-2 and a high areal capacity of 3 mAh cm-2. Moreover, the full cells with these scaffolds further demonstrate high cycling stability under challenging conditions, including high cathode loading of 21.6 mg cm-2, low negative-to-positive ratio of 1.6, and limited electrolyte-to-capacity ratio of 4.2 g Ah-1.

Near-Complete Suppression of NIR-II Luminescence Quenching in Halide Double Perovskites for Surface Functionalization Through Facet Engineering

Lanthanide-based NIR-II-emitting materials (1000-1700 nm) show promise for optoelectronic devices, phototherapy, and bioimaging. However, one major bottleneck to prevent their widespread use lies in low quantum efficiencies, which are significantly constrained by various quenching effects. Here, a highly oriented (222) facet is achieved via facet engineering for Cs2NaErCl6 double perovskites, enabling near-complete suppression of NIR-II luminescence quenching. The optimally (222)-oriented Cs2Ag0.10Na0.90ErCl6 microcrystals emit Er3+ 1540 nm light with unprecedented high quantum efficiencies of 90 ± 6% under 379 nm UV excitation (ultralarge Stokes shift >1000 nm), and a record near-unity quantum yield of 98.6% is also obtained for (222)-based Cs2NaYb0.40Er0.60Cl6 microcrystallites under 980 nm excitation. With combined experimental and theoretical studies, the underlying mechanism of facet-dependent Er3+ 1540 nm emissions is revealed, which can contribute to surface asymmetry-induced breakdown of parity-forbidden transition and suppression of undesired non-radiative processes. Further, the role of surface quenching is reexamined by molecular dynamics based on two facets, highlighting the drastic two-phonon coupling effect of a hydroxyl group to 4I13/2 level of Er3+. Surface-functionalized facets will provide new insights for tunable luminescence in double perovskites, and open up a new avenue for developing highly efficient NIR-II emitters toward broad applications.

Scalable Customization of Crystallographic Plane Controllable Lithium Metal Anodes for Ultralong-Lasting Lithium Metal Batteries

A formidable challenge to achieve the practical applications of rechargeable lithium (Li) metal batteries (RLMBs) is to suppress the uncontrollable growth of Li dendrites. One of the most effective solutions is to fabricate Li metal anodes with specific crystal plane, but still lack of a simple and high-efficient approach. Herein, a facile and controllable way for the scalable customization of polished Li metal anodes with highly preferred (110) and (200) crystallographic orientation (donating as polished Li(110) and polished Li(200), respectively) by regulating the times of accumulative roll bonding, is reported. According to the inherent characteristics of polished Li(110)/Li(200), the influence of Li atomic structure on the electrochemical performance of RLMBs is deeply elucidated by combining theoretical calculations with relative experimental proofs. In particular, a polished Li(110) crystal plane is demonstrated to induce Li+ uniform deposition, promoting the formation of flat and dense Li deposits. Impressively, the polished Li(110)||LiFePO4 full cells exhibit unprecedented cycling stability with 10 000 cycles at 10 C almost without capacity degradation, indicating the great potential application prospect of such textured Li metal. More valuably, this work provides an important reference for low-cost, continued, and large-scale production of Li metal anodes with highly preferred crystal orientation through roll-to-roll manufacturability.

Rational Molecular Engineering via Electron Reconfiguration toward Robust Dual-Electrode/Electrolyte Interphases for High-Performance Lithium Metal Batteries

High-energy-density lithium-metal batteries (LMBs) coupling lithium-metal anodes and high-voltage cathodes are hindered by unstable electrode/electrolyte interphases (EEIs), which calls for the rational design of efficient additives. Herein, we analyze the effect of electron structure on the coordination ability and energy levels of the additive, from the aspects of intramolecular electron cloud density and electron delocalization, to reveal its mechanism on solvation structure, redox stability, as-formed EEI chemistry, and electrochemical performances. Furthermore, we propose an electron reconfiguration strategy for molecular engineering of additives, by taking sorbide nitrate (SN) additive as an example. The lone pair electron-rich group enables strong interaction with the Li ion to regulate solvation structure, and intramolecular electron delocalization yields further positive synergistic effects. The strong electron-withdrawing nitrate moiety decreases the electron cloud density of the ether-based backbone, improving the overall oxidation stability and cathode compatibility, anchoring it as a reliable cathode/electrolyte interface (CEI) framework for cathode integrity. In turn, the electron-donating bicyclic-ring-ether backbone breaks the inherent resonance structure of nitrate, facilitating its reducibility to form a N-contained and inorganic Li2O-rich solid electrolyte interface (SEI) for uniform Li deposition. Optimized physicochemical properties and interfacial biaffinity enable significantly improved electrochemical performance. High rate (10 C), low temperature (-25 °C), and long-term stability (2700 h) are achieved, and a 4.5 Ah level Li||NCM811 multilayer pouch cell under harsh conditions is realized with high energy density (462 W h/kg). The proof of concept of this work highlights that the rational ingenious molecular design based on electron structure regulation represents an energetic strategy to modulate the electrolyte and interphase stability, providing a realistic reference for electrolyte innovations and practical LMBs.

Synergetic regulation of SEI mechanics and crystallographic orientation for stable lithium metal pouch cells

The advancement of Li-metal batteries is significantly impeded by the presence of unstable solid electrolyte interphase and Li dendrites upon cycling. Herein, we present an innovative approach to address these issues through the synergetic regulation of solid electrolyte interphase mechanics and Li crystallography using yttrium fluoride/polymethyl methacrylate composite layer. Specifically, we demonstrate the in-situ generation of Y-doped lithium metal through the reaction of composite layer with Li metal, which reduces the surface energy of the (200) plane, and tunes the preferential crystallographic orientation to (200) plane from conventional (110) plane during Li plating. These changes effectively passivate Li metal, thereby significantly reducing undesired side reactions between Li and electrolytes by 4 times. Meanwhile, the composite layer with suitable modulus (~1.02 GPa) can enhance mechanical stability and maintain structural stability of SEI. Consequently, a 4.2 Ah pouch cell with high energy density of 468 Wh kg-1 and remarkable capacity stability of 0.08% decay/cycle is demonstrated under harsh condition, such as high-areal-capacity cathode (6 mAh cm-2), lean electrolyte (1.98 g Ah-1), and high current density (3 mA cm-2). Our findings highlight the potential of reactive composite layer as a promising strategy for the development of stable Li-metal batteries.

Molecular Engineering toward Robust Solid Electrolyte Interphase for Lithium Metal Batteries

Lithium-metal batteries (LMBs) with high energy density are becoming increasingly important in global sustainability initiatives. However, uncontrollable dendrite seeds, inscrutable interfacial chemistry, and repetitively formed solid electrolyte interphase (SEI) have severely hindered the advancement of LMBs. Organic molecules have been ingeniously engineered to construct targeted SEI and effectively minimize the above issues. In this review, multiple organic molecules, including polymer, fluorinated molecules, and organosulfur, are comprehensively summarized and insights into how to construct the corresponding elastic, fluorine-rich, and organosulfur-containing SEIs are provided. A variety of meticulously selected cases are analyzed in depth to support the arguments of molecular design in SEI. Specifically, the evolution of organic molecules-derived SEI is discussed and corresponding design principles are proposed, which are beneficial in guiding researchers to understand and architect SEI based on organic molecules. This review provides a design guideline for constructing organic molecule-derived SEI and will inspire more researchers to concentrate on the exploitation of LMBs.

Progress and Perspectives on the Development of Pouch-Type Lithium Metal Batteries

Lithium (Li) metal batteries (LMBs) are the "holy grail" in the energy storage field due to their high energy density (theoretically >500 Wh kg-1 ). Recently, tremendous efforts have been made to promote the research & development (R&D) of pouch-type LMBs toward practical application. This article aims to provide a comprehensive and in-depth review of recent progress on pouch-type LMBs from full cell aspect, and to offer insights to guide its future development. It will review pouch-type LMBs using both liquid and solid-state electrolytes, and cover topics related to both Li and cathode (including LiNix Coy Mn1-x-y O2 , S and O2 ) as both electrodes impact the battery performance. The key performance criteria of pouch-type LMBs and their relationship in between are introduced first, then the major challenges facing the development of pouch-type LMBs are discussed in detail, especially those severely aggravated in pouch cells compared with coin cells. Subsequently, the recent progress on mechanistic understandings of the degradation of pouch-type LMBs is summarized, followed with the practical strategies that have been utilized to address these issues and to improve the key performance criteria of pouch-type LMBs. In the end, it provides perspectives on advancing the R&Ds of pouch-type LMBs towards their application in practice.

Hierarchically Interpenetrated and Reentrant Microcellular Frameworks for Stretchable Lithium Metal Batteries

With the rapid development of human-friendly wearable devices, energy storage components are required to have skin-like stretchability or free-form to fit closer and more comfortably to the human body. This study introduces a hierarchically interpenetrated reentrant microcellular structure combined with 2D cellular graphene/MXene/carbon nanotubes (CNTs) and 3D cellular melamine foam. This composite structure works as a stretchable framework of lithium metal composite electrodes to provide stretchability for lithium metal electrodes, which are promising as next-generation energy storage systems. The interpenetrated but independent cellular structures successfully obtain stable structural deformability from the nonconductive and deformable melamine foam, while at the same time, high electrical conductivity, lithiophilicity, and mechanical stability of the graphene/CNT/MXene network serve as a lithium deposition support during the electrodeposition of lithium. The reentrant structure is fabricated by radial compressing the hierarchical cellular structures to take advantage of the structural stretchability of the accordion-like reentrant frameworks. The lithium-deposited composite electrodes exhibit much lower overpotential during Li stripping and plating than lithium metal foil anodes and show stable electrochemical performances under 30% of mechanical strain. The reentrant microcellular electrodes offer great potential for advanced designs of lithium metal electrodes for stretchable batteries with high energy density.

Defect Strategy in Solid-State Lithium Batteries

Solid-state lithium batteries (SSLBs) have great development prospects in high-security new energy fields, but face major challenges such as poor charge transfer kinetics, high interface impedance, and unsatisfactory cycle stability. Defect engineering is an effective method to regulate the composition and structure of electrodes and electrolytes, which plays a crucial role in dominating physical and electrochemical performance. It is necessary to summarize the recent advances regarding defect engineering in SSLBs and analyze the mechanism, thus inspiring future work. This review systematically summarizes the role of defects in providing storage sites/active sites, promoting ion diffusion and charge transport of electrodes, and improving structural stability and ionic conductivity of solid-state electrolytes. The defects greatly affect the electronic structure, chemical bond strength and charge transport process of the electrodes and solid-state electrolytes to determine their electrochemical performance and stability. Then, this review presents common defect fabrication methods and the specific role mechanism of defects in electrodes and solid-state electrolytes. At last, challenges and perspectives of defect strategies in high-performance SSLBs are proposed to guide future research.

Directing (110) Oriented Lithium Deposition through High-flux Solid Electrolyte Interphase for Dendrite-free Lithium Metal Batteries

Controlling lithium (Li) electrocrystallization with preferred orientation is a promising strategy to realize highly reversible Li metal batteries (LMBs) but lack of facile regulation methods. Herein, we report a high-flux solid electrolyte interphase (SEI) strategy to direct (110) preferred Li deposition even on (200)-orientated Li substrate. Bravais rule and Curie-Wulff principle are expanded in Li electrocrystallization process to decouple the relationship between SEI engineering and preferred crystal orientation. Multi-spectroscopic techniques combined with dynamics analysis reveal that the high-flux CF3 Si(CH3 )3 (F3 ) induced SEI (F3 -SEI) with high LiF and -Si(CH3 )3 contents can ingeniously accelerate Li+ transport dynamics and ensure the sufficient Li+ concentration below SEI to direct Li (110) orientation. The induced Li (110) can in turn further promote the surface migration of Li atoms to avoid tip aggregation, resulting in a planar, dendrite-free morphology of Li. As a result, our F3 -SEI enables ultra-long stability of Li||Li symmetrical cells for more than 336 days. Furthermore, F3 -SEI modified Li can significantly enhance the cycle life of Li||LiFePO4 and Li||NCM811 coin and pouch full cells in practical conditions. Our crystallographic strategy for Li dendrite suppression paves a path to achieve reliable LMBs and may provide guidance for the preferred orientation of other metal crystals.

A Stable Triazole-Based Covalent Gel for Long-Term Cycling Zn Anode in Zinc-Ion Batteries

In this work, a functional covalent gel material is developed to resolve the severe dendritic growth and hydrogen evolution reaction toward Zn/electrolyte interface in aqueous zinc-ion batteries (ZIBs). A covalent gel layer with superior durability forms homogeneously on the surface of Zn foil. The covalent gel with triazole functional groups can uniformize the transport of Zn2+ due to the interactions between Zn2+ ions and the triazole groups in the covalent gel. As a consequence, the symmetrical battery with triazole covalent gel maintains stable Zn plating/stripping for over 3000 h at 1 mA cm-2 and 1 mAh cm-2 , and the full cell combined with a V2 O5 cathode operates steadily and continuously for at least 1800 cycles at 5 A g-1 with a capacity retention rate of 67.0%. This work provides a train of thought to develop stable covalent gels for the protection of zinc anode toward high-performance ZIBs.