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Lithium metal batteries (LMBs) with high energy density are perceived as the most promising candidates to enable long-endurance electrified transportation. However, rapid capacity decay and safety hazards have impeded the practical application of LMBs, where the entangled complex degradation pattern remains a major challenge for efficient battery design and engineering. Here, we present an interpretable framework to learn the accelerated aging of LMBs with a comprehensive data space containing 79 cells varying considerably in battery chemistries and cell parameters. Leveraging only data from the first 10 cycles, this framework accurately predicts the knee points where aging starts to accelerate. Leaning on the framework's interpretability, we further elucidate the critical role of the last 10%-depth discharging on LMB aging rate and propose a universal descriptor based solely on early cycle electrochemical data for rapid evaluation of electrolytes. The machine learning insights also motivate the design of a dual-cutoff discharge protocol, which effectively extends the cycle life of LMBs by a factor of up to 2.8.

Li-rich Mn-based cathode materials (LRMO) are promising for enhancing energy density of all-solid-state batteries (ASSBs). Nonetheless, the development of efficient Li + /e - pathways is hindered by the poor electrical conductivity of LRMO cathodes and their incompatible interfaces with solid electrolytes (SEs). Herein, we propose a strategy of in - situ bulk/interfacial structure design to construct fast and stable Li + /e - pathways by introducing Li 2 WO 4 , which reduces the energy barrier for Li + migration and enhances the stability of the surface oxygen structure. The reversibility of oxygen redox was improved, and the voltage decay of the LRMO cathode was addressed significantly. As a result, the bulk structure of the LRMO cathodes and the high-voltage solid-solid interfacial stability are improved. Therefore, the ASSBs achieve a high areal capacity (∼3.15 mAh/cm 2 ) and outstanding cycle stability of ≥1200 cycles with 84.1% capacity retention at 1 C at 25 °C. This study offers new insights into LRMO cathode design strategies for ASSBs, focusing on ultrastable high-voltage interfaces and high-loading composite electrodes.

ConspectusLithium-sulfur (Li-S) batteries have attracted worldwide attention as promising next-generation rechargeable batteries due to their high theoretical energy density of 2600 Wh kg -1 . The actual energy density of Li-S batteries at the pouch cell level has significantly exceeded that of state-of-the-art Li-ion batteries. However, the overall performances of Li-S batteries under practical working conditions are limited by the sluggish conversion kinetics of the sulfur cathodes. To overcome the above challenge, various kinetic promotion strategies have been proposed to accelerate the multiphase and multi-electron cathodic redox reactions between sulfur, lithium polysulfides (LiPSs), and lithium sulfide. Nowadays, kinetic promoters have been massively employed in sulfur cathodes to achieve Li-S batteries with high energy densities, high rates, and long lifespans. A comprehensive and timely summary of cutting-edge kinetic promoters for sulfur cathodes is of great essence to afford an in-depth understanding of the unique Li-S electrochemistry.In this Account, we outline the recent efforts on the design of sulfur cathode kinetic promoters for advanced Li-S batteries. The latest progress is discussed in detail regarding heterogeneous, homogeneous, and semi-immobilized kinetic promoters. Heterogeneous promoters, representatively known as electrocatalysts, function mainly by reducing the energy barriers of the interfacial electrochemical reactions. The working mechanism, activity regulation strategies, and reconstitution/deactivation processes of the heterogeneous promoters are reviewed to provide guiding principles for rational design. In comparison, homogeneous promoters are able to fully contact with the reaction interfaces and regulate the electron/ion-inaccessible reactants in working Li-S batteries. Redox mediators and redox comediators are typical homogeneous promoters. The former establishes extra chemical reaction pathways to circumvent the originally sluggish steps and boost the overall kinetics, while the latter fundamentally modifies the LiPS molecules to enhance their redox kinetics. For semi-immobilized promoters, the active units are generally anchored on the cathode substrate through flexible chains with mobile characteristics. Such a design endows the promoter with both heterogeneous and homogeneous characteristics to comprehensively regulate the multiphase sulfur redox reactions involving both mobile and immobile reactants.Overall, this Account summarizes the fundamental electrochemistry, design principles, and practical promotion effects of the various kinetic promoters used for the sulfur cathodes in Li-S batteries. We believe that this Account will provide an in-depth and cutting-edge understanding of the unique sulfur electrochemistry, thereby providing guidance for further development of high-performance Li-S batteries and analogous rechargeable battery systems.

Lithium-sulfur (Li-S) batteries constitute promising next-generation energy storage devices due to the ultrahigh theoretical energy density of 2600 Wh kg -1 . However, the multiphase sulfur redox reactions with sophisticated homogeneous and heterogeneous electrochemical processes are sluggish in kinetics, thus requiring targeted and high-efficient electrocatalysts. Herein, a semi-immobilized molecular electrocatalyst is designed to tailor the characters of the sulfur redox reactions in working Li-S batteries. Specifically, porphyrin active sites are covalently grafted onto conductive and flexible polypyrrole linkers on graphene current collectors. The electrocatalyst with the semi-immobilized active sites exhibits homogeneous and heterogeneous functions simultaneously, performing enhanced redox kinetics and a regulated phase transition mode. The efficiency of the semi-immobilizing strategy is further verified in practical Li-S batteries that realize superior rate performances and long lifespan as well as a 343 Wh kg -1 high-energy-density Li-S pouch cell. This contribution not only proposes an efficient semi-immobilizing electrocatalyst design strategy to promote the Li-S battery performances but also inspires electrocatalyst development facing analogous multiphase electrochemical energy processes.

Self-healing capability helps biological systems to maintain their survivability and extend their lifespan. Similarly, self-healing is also beneficial to next-generation secondary batteries because high-capacity electrode materials, especially the cathodes such as oxygen or sulfur, suffer from shortened cycle lives resulting from irreversible and unstable phase transfer. Herein, by mimicking a biological self-healing process, fibrinolysis, we introduced an extrinsic healing agent, polysulfide, to enable the stable operation of sulfur microparticle (SMiP) cathodes. An optimized capacity (∼3.7 mAh cm -2 ) with almost no decay after 2000 cycles at a high sulfur loading of 5.6 mg (S) cm -2 was attained. The inert SMiP is activated by the solubilization effect of polysulfides whereas the unstable phase transfer is mediated by mitigated spatial heterogeneity of polysulfides, which induces uniform nucleation and growth of solid compounds. The comprehensive understanding of the healing process, as well as of the spatial heterogeneity, could further guide the design of novel healing agents (e.g., lithium iodine) toward high-performance rechargeable batteries.

The behavior of two-dimensional (2D) materials for energy storage systems relates to their morphology and physicochemical properties. Although various 2D materials can be found in different fields, the open access of these materials has greatly hampered their practical applications, such as in lithium-sulfur (Li-S) batteries, where the soluble intermediates should be controlled. Here, we have developed a facile approach to prepare 2D ultrathin interconnected carbon fabrics (ICFs) with "bubble-like" morphology and abundant mesopores using a "blowing bubble" method. Serving as independent meso-sized rooms, nanosulfur dots can be stitched in 2D "bubble-like" ICF, which afford a short electron-/ion-transfer path and thus is beneficial to high reversible capacity. Encapsulated with reduced graphene oxide, a binder-free/free-standing cathode was constructed for advanced Li-S batteries. In addition, the specific energy of a pouch Li-S battery with this interconnected cathode can be achieved to 1.55 Ah@315.98 Wh/kg at 0.1 C. These results suggest that the design of "bubble-like" interconnected porous carbon fabrics and their integration with reduced graphene oxide provide a facile strategy to enhance the electrochemical activity of S and have the potential to be applied to other semiconductors or insulating materials for a wide range of applications.

Lithium-sulfur (Li-S) battery system is endowed with tremendous energy density, resulting from the complex sulfur electrochemistry involving multielectron redox reactions and phase transformations. Originated from the slow redox kinetics of polysulfide intermediates, the flood of polysulfides in the batteries during cycling induced low sulfur utilization, severe polarization, low energy efficiency, deteriorated polysulfide shuttle, and short cycling life. Herein, sulfiphilic cobalt disulfide (CoS2) was incorporated into carbon/sulfur cathodes, introducing strong interaction between lithium polysulfides and CoS2 under working conditions. The interfaces between CoS2 and electrolyte served as strong adsorption and activation sites for polar polysulfides and therefore accelerated redox reactions of polysulfides. The high polysulfide reactivity not only guaranteed effective polarization mitigation and promoted energy efficiency by 10% but also promised high discharge capacity and stable cycling performance during 2000 cycles. A slow capacity decay rate of 0.034%/cycle at 2.0 C and a high initial capacity of 1368 mAh g(-1) at 0.5 C were achieved. Since the propelling redox reaction is not limited to Li-S system, we foresee the reported strategy herein can be applied in other high-power devices through the systems with controllable redox reactions.

Lithium-sulfur (Li-S) batteries, with a theoretical energy density of 2600 Wh kg(-1), are a promising platform for high-energy and cost-effective electrochemical energy storage. However, great challenges such as fast capacity degradation and safety concerns prevent it from widespread application. With the adoption of Li metal as the anode, dendritic and mossy metal depositing on the negative electrode during repeated cycles leads to serious safety concerns and low Coulombic efficiency. Herein, we report a distinctive graphene framework structure coated by an in situ formed solid electrolyte interphase (SEI) with Li depositing in the pores as the anode of Li-S batteries. The graphene-based metal anode demonstated a superior dendrite-inhibition behavior in 70 h of lithiation, while the cell with a Cu foil based metal anode was short-circuited after only 4 h of lithiation at 0.5 mA cm(-2). The graphene-modified Li anode with SEI induced by the polysulfide-containing electrolyte improved the Coulombic efficiency to ∼97% for more than 100 cycles, while the control sample with Cu foil as the current collector exhibited huge fluctuations in Coulombic efficiency. The unblocked ion pathways and high electron conductivities of frameworks in the modified metal anode led to the rapid transfer of Li ions through the SEI and endowed the anode framework with an ion conductivity of 7.81 × 10(-2) mS cm(-1), nearly quintuple that of the Cu foil based Li metal anode. Besides, the polarization in the charge-discharge process was halved to 30 mV. The stable and efficient Li deposition was maintained after 2000 cycles. Our results indicated that nanoscale interfacial electrode engineering could be a promising strategy to tackle the intrinsic problems of lithium metal anodes, thus improving the safety of Li-S cells.

Lithium-sulfur batteries hold great promise for serving as next generation high energy density batteries. However, the shuttle of polysulfide induces rapid capacity degradation and poor cycling stability of lithium-sulfur cells. Herein, we proposed a unique lithium-sulfur battery configuration with an ultrathin graphene oxide (GO) membrane for high stability. The oxygen electronegative atoms modified GO into a polar plane, and the carboxyl groups acted as ion-hopping sites of positively charged species (Li(+)) and rejected the transportation of negatively charged species (Sn(2-)) due to the electrostatic interactions. Such electrostatic repulsion and physical inhibition largely decreased the transference of polysulfides across the GO membrane in the lithium-sulfur system. Consequently, the GO membrane with highly tunable functionalization properties, high mechanical strength, low electric conductivity, and facile fabrication procedure is an effective permselective separator system in lithium-sulfur batteries. By the incorporation of a permselective GO membrane, the cyclic capacity decay rate is also reduced from 0.49 to 0.23%/cycle. As the GO membrane blocks the diffusion of polysulfides through the membrane, it is also with advantages of anti-self-discharge properties.

Hollow nanostructures afford intriguing structural features ranging from large surface area and fully exposed active sites to kinetically favorable mass transportation and tunable surface permeability. The unique properties and potential applications of graphene nanoshells with well-defined small cavities and delicately designed graphene shells are strongly considered. Herein, a mesoscale approach to fabricate graphene nanoshells with a single or few graphene layers and quite small diameters through a catalytic self-limited assembly of nanographene on in situ formed nanoparticles was proposed. The graphene nanoshells with a diameter of ca. 10-30 nm and a pore volume of 1.98 cm(3) g(-1) were employed as hosts to accommodate the sulfur for high-rate lithium-sulfur batteries. A very high initial discharge capacity of 1520 mAh g(-1), corresponding to 91% sulfur utilization rate at 0.1 C, was achieved on a graphene nanoshell/sulfur composite with 62 wt % loading. A very high retention of 70% was maintained when the current density increased from 0.1 C to 2.0 C, and an ultraslow decay rate of 0.06% per cycle during 1000 cycles was detected.

The theoretically proposed graphene/single-walled carbon nanotube (G/SWCNT) hybrids by placing SWCNTs among graphene planes through covalent C-C bonding are expected to have extraordinary physical properties and promising engineering applications. However, the G/CNT hybrids that have been fabricated differ greatly from the proposed G/SWCNT hybrids because either the covalent C-C bonding is not well constructed or only multiwalled CNTs/carbon nanofibers rather than SWCNTs are available in the hybrids. Herein, a novel G/SWCNT hybrid was successfully fabricated by a facile catalytic growth on layered double hydroxide (LDH) at a high temperature over 950 °C. The thermally stable Fe nanoparticles and the uniform structure of the calcined LDH flakes are essential for the simultaneously catalytic deposition of SWCNTs and graphene. The SWCNTs and the CVD-grown graphene, as well as the robust connection between the SWCNTs and graphene, facilitated the construction of a high electrical conductive pathway. The internal spaces between the two stacked graphene layers and among SWCNTs offer room for sulfur storage. Therefore, the as obtained G/SWCNT-S cathode exhibited excellent performance in Li-S batteries with a capacity as high as 650 mAh g(-1) after 100 cycles even at a high current rate of 5 C. Such a novel G/SWCNT hybrid can serve not only as a prototype to shed light on the chemical principle of G/CNT synthesis but also as a platform for their further applications in the area of nanocomposites, heterogeneous catalysis, drug delivery, electrochemical energy storage, and so on.

Inorganic materials with double-helix structure have attracted intensive attention due to not only their elegant morphology but also their amazing morphology-related potential applications. The investigation on the formation mechanism of the inorganic double-helix nanostructure is the first step for the fundamental studies of their materials or physical properties. Herein, we demonstrated the space confinement and rotation stress induced self-organization mechanism of the carbon nanotube (CNT)-array double helices under scanning electron microscopy by directly observing their formation process from individual layered double hydroxide flakes, which is a kind of hydrotalcite-like material composed of positively charged layers and charge-balancing interlayer anions. Space confinement is considered to be the most important extrinsic factor for the formation of CNT-array double helices. Synchronous growth of the CNT arrays oppositely from LDH flakes with space confinement on both sides at the same time is essential for the growth of CNT-array double helices. Coiling of the as-grown CNT arrays into double helices will proceed by self-organization, tending to the most stable morphology in order to release their internal rotation stress. Based on the demonstrated mechanism, effective routes were carried out to improve the selectivity for CNT-array double helices. The work provides a promising method for the fabrication of double-helix nanostructures with their two helices connected at the end by self-assembly.

The mass transportation mechanism in electric-biased carbon nanotubes (CNTs) is investigated experimentally. Except for the widely accepted electromigration mechanism, we find out the thermal effect can also induce the mass transportation in the form of thermomigration or thermal evaporation. Moreover, the convincing in situ transmission electron microscope experiment results show the thermal gradient force overrides the electromigration force in most conditions, according to specific parameters of the CNTs and "cargos". A full analysis on the thermal gradient force and electromigration force imposed on the cargos is given, thus our experimental results are well explained and understood.

A chemical precursor mediated process was used to form catalyst nanoparticles (NPs) with an extremely high density (10(14) to 10(16) m(-2)), controllable size distribution (3-20 nm), and good thermal stability at high temperature (900 °C). This used metal cations deposited in layered double hydroxides (LDHs) to give metal catalyst NPs by reduction. The key was that the LDHs had their intercalated anions selected and exchanged by guest-host chemistry to prevent sintering of the metal NPs, and there was minimal sintering even at 900 °C. Metal NPs on MoO(4)(2-) intercalated Fe/Mg/Al LDH flakes were successfully used as the catalyst for the double helix growth of single-walled carbon nanotube arrays. The process provides a general method to fabricate thermally stable metal NPs catalysts with the desired size and density for catalysis and materials science.

A surfactant-free two-step shearing strategy was applied to disperse vertically aligned carbon nanotube (VACNT) arrays into individually dispersed CNTs. First, big blocks of VACNT arrays were sheared into fluffy CNTs. The fluffy CNTs were composed of CNT bundles with a diameter of 1-10 microm and a length of several millimeters. After that, the fluffy CNTs were further sheared in liquid phase to obtain individually dispersed CNTs. As comparison, sonication and grinding were also employed for further dispersion of the fluffy CNTs. The length of CNTs dispersed by shearing method was the longest and up to several hundred micrometers. The CNT dispersions from the three methods can be used to fabricate transparent conductive films (TCFs). The TCFs from CNTs dispersed by shearing method showed the highest conductivity at the same transparency. VACNT arrays with a small diameter (approximately 10 nm) were dispersed by the shearing method as well, from which the TCF with a surface resistance of 2.5 kohm/square and a transparency of 78.6% (at 500 nm) was obtained. The ratio of dc to optical conductivity (sigma(dc)/sigma(op)) of the as-dispersed CNT array was 0.711, which can compare beauty with that of single-walled CNTs and double-walled CNTs grown by the CVD process.