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Lithium metal is a possible anode material for building high energy density secondary batteries, but its problems during cycling have hindered the commercialization of lithium metal secondary batteries. Until now, many sophisticated techniques have been used to obtain rich micro‐morphological and physicochemical information of the deposition layer and the solid electrolyte interface (SEI), and to develop improvement strategies based on the information and achieve remarkable results. Regulating the reaction process around key links is a classic strategy to achieve expected results. Based on this empirical fact, we artificially highlighted the differences in the apparent performance of lithium metal anode using different series of electrolytes. We used microelectrode technology to analyze the reaction mechanisms and kinetic characteristics of each elementary step under all electrolyte conditions, revealing common laws that affect apparent performance and the basic steps that have a decisive impact on apparent performance. We discussed and elucidated the relevant physical and chemical principles, providing a clear basis for improving the pertinence and efficiency of improvement strategies. [ABSTRACT FROM AUTHOR]

The demand for innovative batteries with high specific energy densities has increased. Li‐metal batteries employing Li‐metal anodes, regarded as the ultimate anodes with a high theoretical capacity, have been extensively studied over the past few decades. However, the poor reversibility and safety concerns regarding Li‐metal anodes remain unresolved. The importance of the electrode/electrolyte interface, especially the solid electrolyte interphase (SEI), for achieving reversibility of Li metal anodes has been extensively studied. Herein, we focused on the impact of the Li ion transport properties in oligoether (glyme)‐based electrolytes on the deposition/dissolution efficiency of Li metal anodes. Analysis of the low‐frequency impedance spectra of Li‐plated Cu/Li cells revealed that the diffusion resistance of Li ions (Rdiffusion) may be a dominant contributor to the internal resistance of the cells employing glyme‐based electrolytes. A higher Rdiffusion in poor‐mass‐transport electrolytes with a lower Li ion transference number resulted in larger polarization during Li deposition/dissolution, leading to more pronounced unfavorable side reactions and lower Coulombic efficiency. Rdiffusion rather than interfacial resistance affected the reversibility of the Li metal anode. Enhancing the Li ion mass transport ability of electrolytes is important for achieving highly reversible charge‐discharge performance of Li metal anodes at high current densities. [ABSTRACT FROM AUTHOR]

The practical implementation of Li metal anode has long been hindered by the significant challenges of notorious dendritic Li growth and severe interphase instability during repeated cycling. Herein, a highly lithiophilic NiSe‐modified host has rationally been constructed to stabilize Li metal by the facile mechanical rolling strategy. The in situ configurated high‐flux Li2Se‐enriched interphase layer can facilitate the fast interfacial charge transfer, high Li plating/stripping reversibility and homogeneous Li nucleation/growth. Consequently, the achieved modified Li metal demonstrates ultrahigh rate capability (10 mA cm−2) and ultralong‐term cycling stability (6600 cycles) with dendrite‐free Li deposition. The Li|LiFePO4 (LFP) cell exhibits an extraordinarily long lifespan cycling stability over 500 cycles with an ultra‐low decay rate of only ≈0.0092% per cycle at 1 C. Furthermore, the 4.5 V high‐voltage Li|LiCoO2 pouch cell with a high areal capacity (≈1.9 mAh cm−2) still reveals an impressively prolonged cyclability over 200 cycles even under the harsh test condition of low negative‐to‐positive‐capacity (N/P) ratio of ≈3.4 and lean electrolyte of ≈5.5 µL mAh−1. This work provides a facile and scalable strategy toward a highly stable Li metal anode for reliable practical usage. [ABSTRACT FROM AUTHOR]

Solid polymer electrolytes offer a safer alternative to organic liquid electrolytes in high‐voltage lithium metal batteries, yet challenges remain in achieving adequate cyclability, energy density, scalability, and safety. This study presents the cycling performance of 1 Ah high‐voltage lithium polymer batteries featuring a hybrid ceramic polymer electrolyte (HCPE), a lithium metal anode, and a LiNi0.8Mn0.1Co0.1O2 (NMC‐811)‐based positive electrode. The HCPE stands out for its remarkable mechanical properties, with a Young's modulus exceeding 200 MPa at room temperature, providing robust resistance against dendrite formation. The Li||Li symmetric cells exhibited outstanding performance, cycling for over 1000 hours at a capacity of 2 mAh cm−2, highlighting the exceptional attributes of HCPE. Full cell testing is conducted under practical conditions, utilizing various cell configurations, from coin cells to large pouch cells with a 1 Ah capacity, achieving an energy density of nearly 250 Wh kg−1 and promising cyclability with 80% capacity retention after 110 cycles. The study also investigated thermal runaway characteristics, showing comparability with commercial lithium‐ion batteries. This research underscores the scalability and performance of high‐voltage lithium metal polymer batteries, advancing their potential for commercial viability. [ABSTRACT FROM AUTHOR]

Abstract Lithium metal is a possible anode material for building high energy density secondary batteries, but its problems during cycling have hindered the commercialization of lithium metal secondary batteries. Until now, many sophisticated techniques have been used to obtain rich micro‐morphological and physicochemical information of the deposition layer and the solid electrolyte interface (SEI), and to develop improvement strategies based on the information and achieve remarkable results. Regulating the reaction process around key links is a classic strategy to achieve expected results. Based on this empirical fact, we artificially highlighted the differences in the apparent performance of lithium metal anode using different series of electrolytes. We used microelectrode technology to analyze the reaction mechanisms and kinetic characteristics of each elementary step under all electrolyte conditions, revealing common laws that affect apparent performance and the basic steps that have a decisive impact on apparent performance. We discussed and elucidated the relevant physical and chemical principles, providing a clear basis for improving the pertinence and efficiency of improvement strategies.

The current commercially used anode material, graphite, has a theoretical capacity of only 372 mAh/g, leading to a relatively low energy density. Lithium (Li) metal is a promising candidate as an anode for enhancing energy density; however, challenges related to safety and performance arise due to Li's dendritic growth, which needs to be addressed. Owing to these critical issues in Li metal batteries, all-solid-state lithium-ion batteries (ASSLIBs) have attracted considerable interest due to their superior energy density and enhanced safety features. Among the key components of ASSLIBs, solid-state electrolytes (SSEs) play a vital role in determining their overall performance. Various types of SSEs, including sulfides, oxides, and polymers, have been extensively investigated for Li metal anodes. Sulfide SSEs have demonstrated high ion conductivity; however, dendrite formation and a limited electrochemical window hinder the commercialization of ASSLIBs due to safety concerns. Conversely, oxide SSEs exhibit a wide electrochemical window, but compatibility issues with Li metal lead to interfacial resistance problems. Polymer SSEs have the advantage of flexibility; however their limited ion conductivity poses challenges for commercialization. This review aims to provide an overview of the distinctive characteristics and inherent challenges associated with each SSE type for Li metal anodes while also proposing potential pathways for future enhancements based on prior research findings. [ABSTRACT FROM AUTHOR]

Abstract The demand for innovative batteries with high specific energy densities has increased. Li‐metal batteries employing Li‐metal anodes, regarded as the ultimate anodes with a high theoretical capacity, have been extensively studied over the past few decades. However, the poor reversibility and safety concerns regarding Li‐metal anodes remain unresolved. The importance of the electrode/electrolyte interface, especially the solid electrolyte interphase (SEI), for achieving reversibility of Li metal anodes has been extensively studied. Herein, we focused on the impact of the Li ion transport properties in oligoether (glyme)‐based electrolytes on the deposition/dissolution efficiency of Li metal anodes. Analysis of the low‐frequency impedance spectra of Li‐plated Cu/Li cells revealed that the diffusion resistance of Li ions (Rdiffusion) may be a dominant contributor to the internal resistance of the cells employing glyme‐based electrolytes. A higher Rdiffusion in poor‐mass‐transport electrolytes with a lower Li ion transference number resulted in larger polarization during Li deposition/dissolution, leading to more pronounced unfavorable side reactions and lower Coulombic efficiency. Rdiffusion rather than interfacial resistance affected the reversibility of the Li metal anode. Enhancing the Li ion mass transport ability of electrolytes is important for achieving highly reversible charge‐discharge performance of Li metal anodes at high current densities.

Highlights A critical assessment of electrolytes’ limiting factors, which affect the low-temperature performance of Li-metal batteries. Summary of emerging strategies to improve low-temperature performance from the aspects of electrolyte design and electrolyte/electrode interphase engineering. Perspectives and challenges on how to develop creative solutions in electrolytes and correlative materials for low-temperature operation.

This review focuses on the promising technology of solid-state batteries (SSBs) that utilize lithium metal and solid electrolytes. SSBs offer significant advantages in terms of high energy density and enhanced safety. This review categorizes solid electrolytes into four classes: polymer, oxide, hybrid, and sulfide solid electrolytes. Each class has its own unique characteristics and benefits. By exploring these different classes, this review aims to shed light on the diversity of materials and their contributions to the advancement of SSB technology. In order to gain insights into the latest technological developments and identify potential avenues for accelerating the progress of SSBs, this review examines the intellectual property landscape related to solid electrolytes. Thus, this review focuses on the recent SSB technology patent filed by the main companies in this area, chosen based on their contribution and influence in the field of batteries. The analysis of the patent application was performed through the Espacenet database. The number of patents related to SSBs from Toyota, Samsung, and LG is very important; they represent more than 3400 patents, the equivalent of 2/3 of the world's patent production in the field of SSBs. In addition to focusing on these three famous companies, we also focused on 15 other companies by analyzing a hundred patents. The objective of this review is to provide a comprehensive overview of the strategies employed by various companies in the field of solid-state battery technologies, bridging the gap between applied and academic research. Some of the technologies presented in this review have already been commercialized and, certainly, an acceleration in SSB industrialization will be seen in the years to come. [ABSTRACT FROM AUTHOR]

All‐solid‐state Li‐metal batteries (ASLMBs) represent a significant breakthrough in the quest to overcome limitations associated with traditional Li‐ion batteries, particularly in energy density and safety aspects. However, widespread implementation is stymied due to a lack of profound understanding of the complex mechano‐electro‐chemical behavior of Li metal in the ASLMBs. Herein, operando neutron imaging and X‐ray computed tomography (XCT) are leveraged to nondestructively visualize Li behaviors within ASLMBs. This approach offers real‐time observations of Li evolutions, both pre‐ and post‐ occurrence of a "soft short". The coordination of 2D neutron radiography and 3D neutron tomography enables charting of the terrain of Li metal deformation operando. Concurrently, XCT offers a 3D insight into the internal structure of the battery following a "soft short". Despite the manifestation of a "soft short", the persistence of Faradaic processes is observed. To study the elusive "soft short" , phase field modeling is coupled with electrochemistry and solid mechanics theory. The research unravels how external pressure curbs dendrite growth, potentially leading to dendrite fractures and thus uncovering the origins of both "soft" and "hard" shorts in ASLMBs. Furthermore, by harnessing finite element modeling, it dive deeper into the mechanical deformation and the fluidity of Li metal. [ABSTRACT FROM AUTHOR]

The novel ternary Li–Cu–Zn alloy is not a simple mixture of Li–Cu and Li–Zn alloys. Its delithiation skeleton is composed of highly lithiophilic and stable "Li-inactive" CuZn and "Li-active" CuZn 5 phases, effectively suppressing dendrite formation and volume changes in lithium metal anode. [Display omitted] • Multiple alloying reactions in multicomponent Li-rich alloy were discovered for the first time and two new skeletons, i.e., CuZn and CuZn 5 were formed in the Li–Cu–Zn ternary alloy. • The CuZn 5 skeleton is "Li-active" and the CnZn skeleton is "Li-inactive", both of which exhibit superior lithiophilicity and structural stability. • Li–Cu–Zn ternary alloy can mitigate the huge volume change during cycling. • The synergistic effect of CuZn and CuZn 5 realizes a dendrite-free Li deposition behavior. Lithium (Li)-rich ternary alloy, comprising a multi-alloy phase as the built-in three-dimensional (3D) framework and a Li metal phase as a reversible Li reservoir, is a promising high-energy–density anode for rechargeable Li metal batteries. The introduction of metal/metalloid components to the alloy can effectively regulate Li deposition and maintain the dimensional integrity of the Li anode. Herein, the lithium–copper–zinc (Li–Cu–Zn) ternary alloy, as a new type of alloy anode, is synthesized via a facile thermal melting method. The fully delithiated 3D scaffold comprised two Cu–Zn alloy phases named CuZn and CuZn 5. These alloy phases exhibit higher lithiophilicity and structural stability than Li–Zn and Li–Cu alloys. Moreover, the CuZn phase is electrochemically inert, ensuring the geometric stability of the anode, while the CuZn 5 phase can readily undergo alloying reaction with Li to form the LiZn phase, thereby facilitating uniform Li nucleation and deposition. The hybridized multiphase alloy structure and specific energy storage mechanism of the Cu–Zn based alloy scaffold in the ternary alloy anode facilitate dendrite-free Li deposition and prolonged cycle lifetime. The Li metal full battery based on lithium iron phosphate (LiFePO 4) cathode exhibits high cycling stability with high-capacity retention of 95.4% after 1000 cycles at 1C. [ABSTRACT FROM AUTHOR]

Thin intermetallic Li2Te–LiTe3 bilayer (0.75 µm) derived from 2D tellurene stabilizes the solid electrolyte interphase (SEI) of lithium metal and argyrodite (LPSCl, Li6PS5Cl) solid‐state electrolyte (SSE). Tellurene is loaded onto a standard battery separator and reacted with lithium through single‐pass mechanical rolling, or transferred directly to SSE surface by pressing. State‐of‐the‐art electrochemical performance is achieved, e.g., symmetric cell stable for 300 cycles (1800 h) at 1 mA cm−2 and 3 mAh cm−2 (25% DOD, 60 µm foil). Cryo‐stage focused ion beam (Cryo‐FIB) sectioning and Raman mapping demonstrate that the Li2Te–LiTe3 bilayer impedes SSE decomposition. The unmodified Li–LPSCl interphase is electrochemically unstable with a geometrically heterogeneous reduction decomposition reaction front that extends deep into the SSE. Decomposition drives voiding in Li metal due to its high flux to the reaction front, as well as voiding in the SSE due to the associated volume changes. Analysis of cycled SSE found no evidence for pristine (unreacted) lithium metal filaments/dendrites, implying failure driven by decomposition phases with sufficient electrical conductivity that span electrolyte thickness. DFT calculations clarify thermodynamic stability, interfacial adhesion, and electronic transport properties of interphases, while mesoscale modeling examines interrelations between reaction front heterogeneity (SEI heterogeneity), current distribution, and localized chemo‐mechanical stresses. [ABSTRACT FROM AUTHOR]

The design of multifunctional separators can address crucial drawbacks of the lithium‐metal batteries. Here, a novel Janus separator (JS) is developed with tunable properties to prevent internal short circuiting and improve the cathode/electrolyte interface. JS is a P(VdF‐HFP) composite with LLZO facing lithium (Li) anode (Layer A) and N‐CQDs contacting the NMC cathode. Layer A acts as Li‐ion flux regulator to hinder dendrite propagation; Layer B plays multiple roles: i) promotion of better carrier migration, ii) protection from side reactions at the NMC cathode and iii) action as physical barrier against dendrite penetration. Galvanostatic cycling of Li/NMC cells with JS including 5 wt% CQDs demonstrated that JS was effective to avoid self‐discharge and internal short‐circuiting due to dendrite perforation, resulting in enhanced cell lifespan. Specific capacity >150 mAh g−1 with capacity retention of 91 % was delivered over 130 cycles at 1C. This result contrasted with higher capacity loss (>25 %) and cell failure in case of P(VdF‐HFP) and Single Layer A separators, respectively. Post‐mortem SEM on JS confirmed that the introduced functionalities successfully intercept dendrites. ARC overheating tests on JS‐based cells demonstrated a remarkably higher thermal resistance and lower severity of the exothermic phenomena compared to Celgard separators. [ABSTRACT FROM AUTHOR]

We introduce a paradigm of solvent and binder selection for solution-processing Li6PS5Cl solid-state electrolyte particles based on Hansen solubility parameters. Treatment of the Li6PS5Cl in selected solvents results in particle morphological change, but crystallographic structure remains intact. Although solution processing reduced the Li6PS5Cl ionic conductivity, it promotes interfacial stability by alleviating reduction of the solid electrolyte in contact with Li metal. These findings have the potential to enhance the stability, structural integrity, and performance of sulfide solid-state electrolytes in practical applications. [ABSTRACT FROM AUTHOR]

Highlights: A critical assessment of electrolytes' limiting factors, which affect the low-temperature performance of Li-metal batteries. Summary of emerging strategies to improve low-temperature performance from the aspects of electrolyte design and electrolyte/electrode interphase engineering. Perspectives and challenges on how to develop creative solutions in electrolytes and correlative materials for low-temperature operation. Electrolyte design holds the greatest opportunity for the development of batteries that are capable of sub-zero temperature operation. To get the most energy storage out of the battery at low temperatures, improvements in electrolyte chemistry need to be coupled with optimized electrode materials and tailored electrolyte/electrode interphases. Herein, this review critically outlines electrolytes' limiting factors, including reduced ionic conductivity, large de-solvation energy, sluggish charge transfer, and slow Li-ion transportation across the electrolyte/electrode interphases, which affect the low-temperature performance of Li-metal batteries. Detailed theoretical derivations that explain the explicit influence of temperature on battery performance are presented to deepen understanding. Emerging improvement strategies from the aspects of electrolyte design and electrolyte/electrode interphase engineering are summarized and rigorously compared. Perspectives on future research are proposed to guide the ongoing exploration for better low-temperature Li-metal batteries. [ABSTRACT FROM AUTHOR]

The current commercially used anode material, graphite, has a theoretical capacity of only 372 mAh/g, leading to a relatively low energy density. Lithium (Li) metal is a promising candidate as an anode for enhancing energy density; however, challenges related to safety and performance arise due to Li’s dendritic growth, which needs to be addressed. Owing to these critical issues in Li metal batteries, all-solid-state lithium-ion batteries (ASSLIBs) have attracted considerable interest due to their superior energy density and enhanced safety features. Among the key components of ASSLIBs, solid-state electrolytes (SSEs) play a vital role in determining their overall performance. Various types of SSEs, including sulfides, oxides, and polymers, have been extensively investigated for Li metal anodes. Sulfide SSEs have demonstrated high ion conductivity; however, dendrite formation and a limited electrochemical window hinder the commercialization of ASSLIBs due to safety concerns. Conversely, oxide SSEs exhibit a wide electrochemical window, but compatibility issues with Li metal lead to interfacial resistance problems. Polymer SSEs have the advantage of flexibility; however their limited ion conductivity poses challenges for commercialization. This review aims to provide an overview of the distinctive characteristics and inherent challenges associated with each SSE type for Li metal anodes while also proposing potential pathways for future enhancements based on prior research findings.

Lithium metal is regarded as the most promising anode material for next generation high energy density lithium batteries due to its high theoretical capacity and lowest potential versus standard hydrogen electrode. However, lithium dendrite growth and huge volume change during cycling hinder its practical application. It is of great importance to design advanced Li metal anodes to solve these problems. Herein, we report a ZnO-coated Zn foam as the host matrix to pre-store lithium through thermal infusing, achieving a Zn@ZnO foam supported Li composite electrode (LZO). Needlelike ZnO nanofibers grown on the Zn foam greatly increase the surface area and enhance the lithiophilicity of the Zn foam. In situ formed synaptic LiZn layer after lithium infusion can disperse local current density and lower Li diffusion barrier effectively, leading to homogeneous Li deposition behavior, thus suppressing dendrite formation. The porous Zn foam skeleton can accommodate volume variation of the electrode during long-term cycling. Benefiting from these merits, the LZO anode exhibits much better cycle stability and rate capability in both symmetrical and full cells with low voltage hysteresis than the bare Li anode. This work opens a new opportunity in designing high performance composite Li anode for lithium-metal batteries. [ABSTRACT FROM AUTHOR]

This review focuses on the promising technology of solid-state batteries (SSBs) that utilize lithium metal and solid electrolytes. SSBs offer significant advantages in terms of high energy density and enhanced safety. This review categorizes solid electrolytes into four classes: polymer, oxide, hybrid, and sulfide solid electrolytes. Each class has its own unique characteristics and benefits. By exploring these different classes, this review aims to shed light on the diversity of materials and their contributions to the advancement of SSB technology. In order to gain insights into the latest technological developments and identify potential avenues for accelerating the progress of SSBs, this review examines the intellectual property landscape related to solid electrolytes. Thus, this review focuses on the recent SSB technology patent filed by the main companies in this area, chosen based on their contribution and influence in the field of batteries. The analysis of the patent application was performed through the Espacenet database. The number of patents related to SSBs from Toyota, Samsung, and LG is very important; they represent more than 3400 patents, the equivalent of 2/3 of the world’s patent production in the field of SSBs. In addition to focusing on these three famous companies, we also focused on 15 other companies by analyzing a hundred patents. The objective of this review is to provide a comprehensive overview of the strategies employed by various companies in the field of solid-state battery technologies, bridging the gap between applied and academic research. Some of the technologies presented in this review have already been commercialized and, certainly, an acceleration in SSB industrialization will be seen in the years to come.

The All-Solid-State-Battery (ASSB) is projected to offer higher energy density and enhanced safety compared to the current commercial Li-ion battery. In this study, we have used a simple model to evaluate the effect of different cell components on the battery's overall performance. We critically examine the promised 100% increase (vs. a standard Li-ion battery) in the overall energy density of an ASSB— a claim often made in both the literature and industry. Through a survey of cell parameters possible with current technology, we were able to evaluate optimum parameters that can be expected in future ASSBs. Herein, we identify three critical parameters required to reach the promised energy density: (1) minimize the thickness of the solid electrolyte to less than 20 μm; (2) modify the cathode formulation to minimize the amount of catholyte and optimize the electrode thickness; and (3) minimize the N/P ratio by developing cells that are anode-free or utilize ultrathin lithium anodes. In conclusion, we believe that the often-cited 100% improvement in energy density for ASSBs is overly optimistic. Instead, a 30% improvement is a more reasonable target for the near future.

[Display omitted] Polyvinylidene difluoride (PVDF) is one of the most attractive electrolyte materials for solid-state batteries due to its high ionic conductivity, however, the battery performance is limited by the high electrolyte–electrode interfacial resistance. Herein, PVDF polymer mixed with ceramic Li 7 La 3 Zr 2 O 12 is coated on cellulose support membrane (PLCSM) through a simple slurry-casting method. The ionic transport of PLCSM is originated from dimethyl formamide (DMF)-Li+ solvation structure, which plays a critical role in conducting lithium ions. β-PVDF after dehydrofluorination offers a high dielectric constant and enhances the dissociation of lithium salt. As a result, PLCSM with a total thickness of 85 µm presents an oxidation voltage of 4.9 V. Li-Li symmetric cells by employing PLCSM reveal that the critical current density (CCD) is increased to 1 mA cm−2. A full cell of LiFePO 4 |PLCSM |Li with high mass loading (1.2 mA h cm−2) shows a first-cycle discharge capacity of 160 mA h g−1. With LiNi 0.6 Mn 0.2 Co 0.2 O 2 as the cathode, the initial discharge capacity is 153 mA h g−1, and the capacity retention after 80 cycles is 80 %. The sandwiched PLCSM provides an effective strategy to achieve high-performance dendrite-free Li metal batteries. [ABSTRACT FROM AUTHOR]

An interlayer is usually employed to tackle the interfacial instability issue between solid electrolytes (SEs) and Li metal caused by the side reaction. However, the failure mechanism of the ionic conductor interlayers, especially the influence from electron penetration, remains largely unknown. Herein, using Li1.3Al0.3Ti1.7(PO4)3 (LATP) as the model SE and LiF as the interlayer, we use metal semiconductor contact barrier theory to reveal the failure origin of Li/LiF@LATP interface based on the calculation results of density functional theory (DFT), in which electrons can easily tunnel through the LiF grain boundary with F vacancies due to its narrow barrier width against electron injection, followed by the reduction of LATP. Remarkably, an Al-LiF bilayer between Li/LATP is found to dramatically promote the interfacial stability, due to the highly increased barrier width and homogenized electric field at the interface. Consequently, the Li symmetric cells with Al-LiF bilayer can exhibit excellent cyclability of more than 2,000 h superior to that interlayered by LiF monolayer (∼ 860 h). Moreover, the Li/Al-LiF@LATP/LiFePO4 solid-state batteries deliver a capacity retention of 83.2% after 350 cycles at 0.5 C. Our findings emphasize the importance of tuning the electron transport behavior by optimizing the potential barrier for the interface design in high-performance solid-state batteries. [ABSTRACT FROM AUTHOR]

Lithium metal has been considered the "holy grail" anode material for rechargeable batteries despite the fact that its dendritic growth and low Coulombic efficiency (CE) have crippled its practical use for decades. Its high chemical reactivity and low stability make it difficult to explore the intrinsic chemical and physical properties of the electrochemically deposited lithium (EDLi) and its accompanying solid electrolyte interphase (SEI). To prevent the dendritic growth and enhance the electrochemical reversibility, it is crucial to understand the nano- and mesostructures of EDLi. However, Li metal is very sensitive to beam damage and has low contrast for commonly used characterization techniques such as electron microscopy. Inspired by biological imaging techniques, this work demonstrates the power of cryogenic (cryo)-electron microscopy to reveal the detailed structure of EDLi and the SEI composition at the nanoscale while minimizing beam damage during imaging. Surprisingly, the results show that the nucleation-dominated EDLi (5 min at 0.5 mA cm-2) is amorphous, while there is some crystalline LiF present in the SEI. The EDLi grown from various electrolytes with different additives exhibits distinctive surface properties. Consequently, these results highlight the importance of the SEI and its relationship with the CE. Our findings not only illustrate the capabilities of cryogenic microscopy for beam (thermal)-sensitive materials but also yield crucial structural information on the EDLi evolution with and without electrolyte additives.

Li10GeP2S12 (LGPS) solid electrolyte with extremely high ionic conductivity is a promising candidate for all‐solid‐state lithium batteries. However, continued LGPS reduction at Li/LGPS interface is huge challenge. Thus, developing a simple and effective strategy to improve Li/LGPS interfacial stability is highly urgent. Herein, LiF‐rich multifunctional interfaces on Li metal (Li@LiF), consisting of three functional components of LiF, carbon particles, and thin CF bond top‐layer, are in situ constructed on the Li metal surface by spontaneous reaction between Li metal and poly(tetrafluoroethylene) at room temperature. LiF, as the main component, significantly suppresses the interfacial reaction due to low electronic conductivity and promotes smooth lithium plating on the Li metal surface arising from high interfacial energy against Li. Meanwhile, carbon particles with excellent Li+ affinity and thin strong polar CF bond top‐layer enable homogenous Li+ flux as well as fast Li+ migration across the LiF‐rich interface, respectively. Consequently, the LGPS‐based symmetric lithium cell possesses significantly prolonged cycling stability and increased critical current density. The LGPS‐based all‐solid‐state lithium cells employing LiCoO2 cathode and Li@LiF anode exhibit excellent rate capability and impressive cycling stability, achieving a high capacity retention of 80.9% over 300 cycles at 0.1 C under 25 °C. [ABSTRACT FROM AUTHOR]

Lithium metal anodes may allow the energy density limit of rechargeable lithium batteries to be pushed higher. However, simple and efficient processing technologies for thin Li metal are lacking, which has significantly limited its applications. Herein, the feasibility of engineering Li metal by compositing it with ferromagnetic particles (termed magnetic Li, abbr. M‐Li) is reported. Due to its magnetic response, straightforward processing of M‐Li on diverse substrates with customized patterns and desired thickness is realized. Moreover, when a garnet‐type solid‐state electrolyte Li6.5La3Zr1.5Ta0.5O12 (LLZTO) is the substrate, intimate contact between M‐Li and LLZTO is obtained, with a low interfacial resistance of ≈11 Ω cm2. In addition to facilitating movement and wetting on various substrates, magnetic transfer of M‐Li sheets to designated locations is also enabled. The intriguing and brand‐new method for Li metal engineering via magnetic actuation may be adopted by the industrial system for the fabrication of Li metal batteries, extended to other alkali metals and promises further progress. [ABSTRACT FROM AUTHOR]

The commercialization of lithium–sulfur (Li−S) batteries is still hindered by the unsatisfactory cell performance under practical working conditions, which is mainly caused by the sluggish cathode redox kinetics, severe polysulfide shuttling, and poor Li stripping/plating reversibility. Herein, we report an effective strategy by combining Se‐doped S hosted in an ordered macroporous framework with a highly fluorinated ether (HFE)‐based electrolyte to simultaneously address the aforementioned issues in both cathode and anode. A reversible and stable high areal capacity of >5.4 mAh cm−2 with high Coulombic efficiency >99.2 % can be achieved under high areal Se/S loading (5.8 mg cm−2), while the underlying mechanism was further revealed through synchrotron X‐ray probes and Time‐of‐Flight Secondary Ion Mass Spectrometry (ToF‐SIMS). The practical application potential was further evaluated at low (0 °C) and high (55 °C) temperatures under high areal Se/S loading (>5.0 mg cm−2) and thin Li metal (40 μm). [ABSTRACT FROM AUTHOR]

As the electrification of the transportation industry is accelerating, the energy storage markets are trying to secure more reliable and environmentally benign materials. Advanced materials are the key performance enablers of batteries as well as a key element determining the cost structure, environmental impact, and recyclability of battery cells. In this review, we analyzed the state-of-the-art cell chemistries and active electrode and electrolyte materials for electric vehicles batteries, which we believe will dominate the battery chemistry landscape in the next decade. We believe that major breakthroughs and innovations in electrode materials such as high-nickel cathodes and silicon and metallic lithium anodes, along with novel liquid electrolyte formulations and solid-state electrolytes, will significantly improve the specific capacity of lithium batteries and reduce their cost, leading to accelerated mass-market penetration of EVs. [ABSTRACT FROM AUTHOR]

Silicon (Si) is one of the most promising anode candidates to further push the energy density of lithium ion batteries. However, its practical usage is still hindered by parasitic side reactions including electrolyte decomposition and continuous breakage and (re‐)formation of the solid electrolyte interphase (SEI), leading to consumption of active lithium. Pre‐lithiation is considered a highly appealing technique to compensate for active lithium losses. A critical parameter for a successful pre‐lithiation strategy by means of Li metal is to achieve lithiation of the active material/composite anode at the most uniform lateral and in‐depth distribution possible. Despite extensive exploration of various pre‐lithiation techniques, controlling the lithium amount precisely while keeping a homogeneous lithium distribution remains challenging. Here, the thermal evaporation of Li metal as a novel pre‐lithiation technique for pure Si anodes that allows both, that is, precise control of the degree of pre‐lithiation and a homogeneous Li deposition at the surface is reported. Li nucleation, mechanical cracking, and the ongoing phase changes are thoroughly evaluated. The terms dry‐state and wet‐state pre‐lithiation (without/with electrolyte) are revisited. Finally, a series of electrochemical methods are performed to allow a direct correlation of pre‐SEI formation with the electrochemical performance of pre‐lithiated Si. [ABSTRACT FROM AUTHOR]

Solid‐electrolytes (SEs) can provide a pathway to increase energy‐density in lithium metal batteries. However, lithium metal penetration through garnet based LLZO solid electrolytes has been identified as a critical failure process. This phenomenon is related to chemo‐mechanical processes which are difficult to probe. In particular, characterizing the dynamic mechanical deformations that occur in electrode‐SE structures is very challenging. This study reports in situ curvature measurements that are thus designed to probe chemo‐mechanical phenomena that occur during lithium plating. The novel experimental cell configuration created for this work shows that pressure builds up in the Li metal during plating, up until the point where short circuits occur. The resulting data are analyzed with a detailed finite element model (FEM) to quantitatively evaluate stress evolution. The results show that Li metal plating within a surface flaw can produce stress build‐up prior to short‐circuiting. The combined results from both the experiments and the FEM suggest that it is critical to minimize surface defects and flaws during the manufacturing processes. [ABSTRACT FROM AUTHOR]

Rough Li plating, low ionic conductivity, and low thermal stability of conventional electrolytes post‐primary challenges for achieving reliable high‐capacity rechargeable lithium batteries, for which lithium metal is frequently proposed as the most promising anode material. Conventional low‐polarity commercial polypropylene/polyethylene separators fail to support the application of high‐energy‐density Li anodes due to their rigid physicochemical properties and the high reactivity of Li metal, leading to fatal dendrite formation and vigorous exothermic reaction with electrolytes. Herein, we develop a Li‐wetting, flame‐retardant binary polymer electrolyte by functionalizing poly(vinylidene fluoride) (PVDF) separators with nonflammable polybenzimidazole (PBI) to build safe room‐temperature solid‐state electrolyte membranes. A dendrite‐free LiFePO4 cell with the solid polymer electrolyte (SPE) delivers a discharge capacity of 127 mAh g−1 at 25°C with a capacity retention of 87.5% after 500 cycles at 0.5°C (0.15 mA cm−2). Phase‐field simulations and density functional theory calculations demonstrate that the negatively charged benzimidazole chains of PBI own superior affinity to lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and shares overlapping electron density with Li anode, giving rise to accelerated Li+ conduction at room temperature and uniform Li electrodeposition at the electrolyte/Li metal interface. The SPE is also flame‐retardant since heat‐resistant polytetrafluoroethylene and a dense, heat‐blocking graphitized carbon layer are formed in intense heat through dehydrogenation/fluorination of PVDF under the catalysis of Lewis base imidazole rings and the decomposition of benzimidazole rings in PBI. No such fire‐resistant mechanism is ever reported in conventional electrolytes. [ABSTRACT FROM AUTHOR]

Abstract Lithium dendrites cause battery failures and safety hazards in liquid‐electrolyte lithium‐based batteries. To address this problem, each component of the battery, such as cathode, anode, electrolyte and separator, should be well matched and engineered for the integrated battery system. The separator plays an increasingly important role owing to its gradual transformation from an inert to an active component in the battery, especially for resolving Li dendrite issues in Li‐metal batteries. Armed with advanced nanotechnology solutions, separator engineering presents a formidable strategy to suppress dendrite growth dynamics by modifying the electrolyte chemistry, regulating/trapping unwanted ionic species and redirecting dendrite growth direction. This review summarizes recent advances in separator engineering for effective dendrite suppression of Li‐metal anodes. We first introduce the challenges that the Li‐metal anode faces and the irreplaceable role of separators in the battery system. The characterization parameters and design principles of separators are also discussed. Then, the mainstream techniques for separator functionalization and their impacts on dendrite suppression are scrutinized and highlighted. Lastly, the conclusion is drawn and the future outlook for separator engineering is presented.

The utilization of lithium (Li) metal as an anode in batteries has drawn significant research interest. However, its widespread adoption has been hampered by the formation of Li dendrites and associated irreversible effects. In this study, we aim to develop a sulfur-rich inorganic solid electrolyte interphase (SEI) by incorporating Sodium 3,3′-dithiodipropane sulfonate (SPS) into a 1,3-dioxopentane/1,2-dimethoxyethane (DME/DOL) based electrolyte. The desolvation kinetics are accelerated by the unique solvation shell containing anions, as evidenced by both theoretical models and experimental data. Additionally, the combined effects of the additives lower the Li+ diffusion energy barrier significantly, promoting the deposition of compact and chunky Li, thereby facilitating the creation of an additive-derived sulfur enhanced inorganic-rich SEI. Consequently, the resultant SEI is enriched with lithium sulfide (Li 2 S), leading to enhanced coulombic efficiency, rate capability, and cyclic stability while reducing polarization potential. Symmetrical Li | Li cells subject to high current density and capacity (5.0 mA cm−2 and 15 mAh cm−2) demonstrate stable cycling for over 750 h. This technology demonstrates the potential to enhance the efficiency and reliability of batteries that use lithium metal anodes by reducing the formation of dendrites. • SPS creation of an additive-derived, enhanced sulfur-rich inorganic SEI. • The sulfur-rich SEI promotes the deposition of compact and chunky Li. • Li.| Li symmetrical cells display a stable cycle over 750 h at 5 mA/cm2. [ABSTRACT FROM AUTHOR]

Extensive research has focused on the lithium (Li) metal anode, but progress in developing this technology has been hindered by the formation of lithium dendrites and their irreversible effects. In this study, an inorganic LiF-Li 3 N-rich solid electrolyte interface (SEI) is established in ether electrolyte through the direct use of 2,3-difluoro-5-(trifluoromethyl)pyridine (DP) to enable uniform Li deposition and enhance interfacial properties for a stable Li metal anode. Theoretical calculations show that DP has a higher tendency to decompose on lithium metal. An alternative approach involving the inclusion of additional anions into the solvation sheath of Li+ ions using weakly solvating solvents is proposed. During Li plating, DP is reduced to form a LiF and Li 3 N-rich SEI, resulting in a heterogeneous SEI layer on the Li metal anode surface. This approach allows stable cycling of Li|Li cells for over 1800 h at current densities of 5 mA cm−2 and 15 mAh cm−2. The method presented here has potential significance in the identification of suitable electrolytes for future research on lithium metal anodes. [ABSTRACT FROM AUTHOR]

The key role played by carbon dioxide in global temperature cycles has stimulated constant research attention on carbon capture and storage. Among the various options, lithium–carbon dioxide batteries are intriguing, not only for the transformation of waste carbon dioxide to value-added products, but also for the storage of electricity from renewable power resources and balancing the carbon cycle. The development of this system is still in its early stages and faces tremendous hurdles caused by the introduction of carbon dioxide. In this review, detailed discussion on the critical problems faced by the electrode, the interface, and the electrolyte is provided, along with the rational strategies required to address these problematic issues for efficient carbon dioxide fixation and conversion. We hope that this review will provide a resource for a comprehensive understanding of lithium–carbon dioxide batteries and will serve as guidance for exploring reversible and rechargeable alkali metal-based carbon dioxide battery systems in the future.

Abstract Rough Li plating, low ionic conductivity, and low thermal stability of conventional electrolytes post‐primary challenges for achieving reliable high‐capacity rechargeable lithium batteries, for which lithium metal is frequently proposed as the most promising anode material. Conventional low‐polarity commercial polypropylene/polyethylene separators fail to support the application of high‐energy‐density Li anodes due to their rigid physicochemical properties and the high reactivity of Li metal, leading to fatal dendrite formation and vigorous exothermic reaction with electrolytes. Herein, we develop a Li‐wetting, flame‐retardant binary polymer electrolyte by functionalizing poly(vinylidene fluoride) (PVDF) separators with nonflammable polybenzimidazole (PBI) to build safe room‐temperature solid‐state electrolyte membranes. A dendrite‐free LiFePO4 cell with the solid polymer electrolyte (SPE) delivers a discharge capacity of 127 mAh g−1 at 25°C with a capacity retention of 87.5% after 500 cycles at 0.5°C (0.15 mA cm−2). Phase‐field simulations and density functional theory calculations demonstrate that the negatively charged benzimidazole chains of PBI own superior affinity to lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and shares overlapping electron density with Li anode, giving rise to accelerated Li+ conduction at room temperature and uniform Li electrodeposition at the electrolyte/Li metal interface. The SPE is also flame‐retardant since heat‐resistant polytetrafluoroethylene and a dense, heat‐blocking graphitized carbon layer are formed in intense heat through dehydrogenation/fluorination of PVDF under the catalysis of Lewis base imidazole rings and the decomposition of benzimidazole rings in PBI. No such fire‐resistant mechanism is ever reported in conventional electrolytes.

The forming of Li-Bi alloy can build a lithiophilic protective layer on the lithium anode, however, it is found that the lithium dendrites trend to grow on the surface of bismuth-rich solid electrolyte interphase (SEI) and there is an exfoliation of SEI from substrate caused by de-alloying process at a large current density. The failure cause of the bismuth-rich SEI is considered as the inadequate Li-ionic conductivity of the passivation layer, which cannot facilitate the lithium deposition on the substrate. Then the components with high Li-ionic conductivities such as Li 3 N, LiF and Li 2 S are introduced into the SEI to adjust the characteristic of the bismuth-rich layer by the addition of LiNO 3 , Bi 2 S 3 and FEC. All of them enhance the SEI's performances effectively and LiNO 3 presents the best. With the addition of LiNO 3 , the SEI thickness is decreased and Li-ionic conductivity is enhanced while Li 3 N became one of the major components of the layer. Utilizing the improved bismuth-rich protective layer the Li/Li symmetric cell presents an overpotential at ∼10 mV in a long cycle over ∼1700 h at 4 mA cm−2, and the LiFePO 4 /Li cell with the cathode loading of ∼10 mg cm−2 exhibits a capacity retention rate 72.1% in 400 cycles. This work provides a new SEI design strategy for lithium metal anode operating at high current density and an inspiration for improving other functional interfacial layers in lithium batteries. • Lithium bismuth alloy and dendrites trend to dealloy and grow on the SEI at high current density. • Additives enhancing Li-ionic conductivities are introduced to adjust the bismuth-rich layer's components. • Lithium nitrate addition make Li 3 N a major component of the layer and significantly enhances SEI electrochemical properties. [ABSTRACT FROM AUTHOR]

• It is a facile and inexpensive strategy employing g-C 3 N 4 layer to modified the Li metal. • The Li-GCN/sulfide solid electrolyte interfacial side reactions are revealed to be significantly inhibited. • The abundant nitrogen species within Li-GCN interphase homogenize the distribution of Li ions flux. • The all-solid-state Li-GCN/LPSC/SPAN battery delivers an excellent capacity retention of 88% after 150 cycles. Sulfide solid-state electrolytes (SSEs) are expected to fundamentally avoid the polysulfides shuttle and Li dendrites growth in the traditional liquid electrolyte lithium-sulfur (Li-S) batteries owing to its ultrahigh ionic conductivity, the high mechanical strength and favorable interfacial compatibility with sulfide-based cathodes. However, the sulfide SSEs are thermodynamically unstable to Li metal, and the parasitic reactions between the Li anode and sulfide SSEs results in intolerable interface deterioration. Herein, a graphitic carbon nitride (GCN, g-C 3 N 4)-dominated artificial interlayer was introduced to enhance the interfacial stability between Li metal and sulfide SSEs. The introduction of electrochemically inert GCN is revealed to effectively alleviate the formation of heterogenous resistance layers for long-term. Furthermore, the abundant nitrogen species within GCN layer homogenize the distribution of Li ions flux, which effectively smooths Li deposition and suppresses dendrites growth. Herein, the symmetric cells with the Li-GCN show a stable plating/stripping cycling for over 1100 h at 0.2 mA cm−2 and a capacity of 0.2 mAh cm−2. The all-solid-state Li-SPAN battery with g-C 3 N 4 interphase exhibits a highly reversible capacity of 579 mAh g−1 and a capacity retention of 88% at 0.2C after 150 cycles, as well as achieves an excellent rate performance. [ABSTRACT FROM AUTHOR]

The oxidization of pure Li is rarely discussed, but substantially important in the design and optimization, especially the failure mechanism of Li metal anode for rechargeable batteries. In this context, the Li metal and inherent LiLi2O interface after oxidization are examined using first principles calculations. The results demonstrated that in Li itself, the Li ion exhibits a fluid-like transport feature, especially in the vacancy-assisted migration. The fresh Li surface can be oxidized quickly in air with a thick cover (mainly Li oxides), and an inherent LiLi2O interface is, therefore, introduced. With the lowest surface energy, the Li (111) plane is revealed with a strong capability of adsorbing O and N atoms to form the distorted XLi6 (X = O, N, etc.) octahedra in the outmost surface layers. Although the Li ion migrates fast in Li itself, the LiLi2O interface shows a sluggish Li diffusion kinetic in Li2O side. This ultimately leads to the Li diffusion prefers to go along the interface boundary in Li side, which loosens the LiLi2O interface structure to result in the exfoliation of surface metastable Li2O spontaneously during electrochemical cycles in Li-metal batteries.

Solid‐state batteries have been considered as promising next‐generation energy storage devices for potentially higher energy density and better safety compared with commercial lithium‐ion batteries that are based on organic liquid electrolytes. However, in terms of indispensable solid‐state electrolytes, there are remaining issues to be solved before entering the market. Most solid‐state electrolytes are air‐sensitive, which causes a complex and expensive cell assembly and impressible interface. Therefore, the solid‐state electrolytes are expected to be atmosphere‐stable, which will undoubtedly bring significant benefits to solid‐state battery manufacturing. This review covers air‐stability‐related issues of different types of inorganic solid‐state electrolytes and the corresponding strategies. First, we provide an overview of solid‐state electrolytes and solid‐state batteries, including their history and advantages/disadvantages. Then, different types of solid‐state electrolytes are selected as examples to illustrate the unfavorable interactions in air and the corresponding adverse effects. Next, according to recent advances, we summarize the effective strategies of constructing different types of air‐stable inorganic solid‐state electrolytes. Finally, perspectives on designing accessible air‐stable solid‐state electrolytes are provided, aiming to achieve the assembly of high‐performance solid‐state batteries in the atmosphere. [ABSTRACT FROM AUTHOR]

Lithium (Li) metal is considered to be the most ideal anode for rechargeable Li-metal batteries due to its high theoretical specific capacity and low redox potential. However, the Li dendrite problem associated with Li metal anodes limits its practical application. Herein, a new chemical dealloying method that adjust the pore structure formed during chemical dealloying at room temperature to prepare a porous Copper current collector which was to enable dendrite-free Li deposition. Benefiting from the naturally formed suitable size and uniform porous structure, this current collector provides larger surface area to homogenize the Li ion distribution and promote dendrite-free Li metal anode with improved Coulombic efficiency (96% for over 210 cycles at the current density of 0.5 mA cm−2 and 95% for 80 cycles at 1.0 mA cm−2). This work provides a novel way to suppress Li dendrite. [ABSTRACT FROM AUTHOR]

Abstract Solid‐state batteries have been considered as promising next‐generation energy storage devices for potentially higher energy density and better safety compared with commercial lithium‐ion batteries that are based on organic liquid electrolytes. However, in terms of indispensable solid‐state electrolytes, there are remaining issues to be solved before entering the market. Most solid‐state electrolytes are air‐sensitive, which causes a complex and expensive cell assembly and impressible interface. Therefore, the solid‐state electrolytes are expected to be atmosphere‐stable, which will undoubtedly bring significant benefits to solid‐state battery manufacturing. This review covers air‐stability‐related issues of different types of inorganic solid‐state electrolytes and the corresponding strategies. First, we provide an overview of solid‐state electrolytes and solid‐state batteries, including their history and advantages/disadvantages. Then, different types of solid‐state electrolytes are selected as examples to illustrate the unfavorable interactions in air and the corresponding adverse effects. Next, according to recent advances, we summarize the effective strategies of constructing different types of air‐stable inorganic solid‐state electrolytes. Finally, perspectives on designing accessible air‐stable solid‐state electrolytes are provided, aiming to achieve the assembly of high‐performance solid‐state batteries in the atmosphere.

The scanning droplet cell (SDC) allows for automatized electrochemical experiments leading to time‐saving and reproducible experimental conditions. Its implementation for non‐aqueous battery research is discussed, and the necessary adaptations to be operated inside an Ar‐filled glovebox in complete absence of oxygen and moisture are described. Due to the importance of the use of Li metal electrodes for next‐generation high‐energy batteries, the complex multi‐parameter optimisation of the Li plating/stripping processes are investigated by means of the SDC. In particular, the influence of pulsed Li plating protocols on the coulombic efficiency is evaluated. The results clearly show that fine tuning of the parameters of pulsed Li plating protocols, i. e. the relaxation period and Li plating duration, is required to improve Li plating efficiencies at high current densities. [ABSTRACT FROM AUTHOR]

Lithium dendrites cause battery failures and safety hazards in liquid‐electrolyte lithium‐based batteries. To address this problem, each component of the battery, such as cathode, anode, electrolyte and separator, should be well matched and engineered for the integrated battery system. The separator plays an increasingly important role owing to its gradual transformation from an inert to an active component in the battery, especially for resolving Li dendrite issues in Li‐metal batteries. Armed with advanced nanotechnology solutions, separator engineering presents a formidable strategy to suppress dendrite growth dynamics by modifying the electrolyte chemistry, regulating/trapping unwanted ionic species and redirecting dendrite growth direction. This review summarizes recent advances in separator engineering for effective dendrite suppression of Li‐metal anodes. We first introduce the challenges that the Li‐metal anode faces and the irreplaceable role of separators in the battery system. The characterization parameters and design principles of separators are also discussed. Then, the mainstream techniques for separator functionalization and their impacts on dendrite suppression are scrutinized and highlighted. Lastly, the conclusion is drawn and the future outlook for separator engineering is presented. [ABSTRACT FROM AUTHOR]