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Abstract The low ionic conductivity of composite solid-state electrolytes due to the lack of free Li-ions and Li dendrite growth induced by the low transference number seriously hinder their application. Herein, we find that the giant dielectric ceramic of Li0.3Ti0.02Ni0.68O (LTNO) with ultra-high dielectric constant can greatly promote the dissociation of Li salt to generate abundant movable Li-ions and realize a high room-temperature ionic conductivity (4.09 × 10–4 S cm−1) as well as a low activation energy (0.16 eV). The oxygen vacancies on the surface of LTNO can effectively immobilize the anions to achieve a high Li transference number (0.61). Furthermore, the enhanced dielectric properties of the composite electrolyte induce homogenous Li plating/stripping to suppress the growth of Li dendrites. As a result, the Li||Li symmetric cells exhibit long lifespan of 2400 h and 1150 h at 0.1 mA cm−2 and 0.2 mA cm−2, respectively. The Li||LiNi0.8Co0.1Mn0.1O2 solid-state full cells show a high capacity retention of 83% after 430 cycles at 2C. This work highlights the critical role of high dielectric property and oxygen defects of fillers in composite solid-state electrolytes, and provides a demonstration for the application of giant dielectric materials in solid-state Li metal batteries.

Abstract The application of lithium‐based batteries is challenged by the safety issues of leakage and flammability of liquid electrolytes. Polymer electrolytes (PEs) can address issues to promote the practical use of lithium metal batteries. However, the traditional preparation of PEs such as the solution‐casting method requires a complicated preparation process, especially resulting in side solvents evaporation issues. The large thickness of traditional PEs reduces the energy density of the battery and increases the transport bottlenecks of lithium‐ion. Meanwhile, it is difficult to fill the voids of electrodes to achieve good contact between electrolyte and electrode. In situ polymerization appears as a facile method to prepare PEs possessing excellent interfacial compatibility with electrodes. Thus, thin and uniform electrolytes can be obtained. The interfacial impedance can be reduced, and the lithium‐ion transport throughput at the interface can be increased. The typical in situ polymerization process is to implant a precursor solution containing monomers into the cell and then in situ solidify the precursor under specific initiating conditions, and has been widely applied for the preparation of PEs and battery assembly. In this review, we focus on the preparation and application of in situ polymerization method in gel polymer electrolytes, solid polymer electrolytes, and composite polymer electrolytes, in which different kinds of monomers and reactions for in situ polymerization are discussed. In addition, the various compositions and structures of inorganic fillers, and their effects on the electrochemical properties are summarized. Finally, challenges and perspectives for the practical application of in situ polymerization methods in solid‐state lithium‐based batteries are reviewed.

Abstract Silicon (Si)‐based solid‐state batteries (Si‐SSBs) are attracting tremendous attention because of their high energy density and unprecedented safety, making them become promising candidates for next‐generation energy storage systems. Nevertheless, the commercialization of Si‐SSBs is significantly impeded by enormous challenges including large volume variation, severe interfacial problems, elusive fundamental mechanisms, and unsatisfied electrochemical performance. Besides, some unknown electrochemical processes in Si‐based anode, solid‐state electrolytes (SSEs), and Si‐based anode/SSE interfaces are still needed to be explored, while an in‐depth understanding of solid–solid interfacial chemistry is insufficient in Si‐SSBs. This review aims to summarize the current scientific and technological advances and insights into tackling challenges to promote the deployment of Si‐SSBs. First, the differences between various conventional liquid electrolyte‐dominated Si‐based lithium‐ion batteries (LIBs) with Si‐SSBs are discussed. Subsequently, the interfacial mechanical contact model, chemical reaction properties, and charge transfer kinetics (mechanical–chemical kinetics) between Si‐based anode and three different SSEs (inorganic (oxides) SSEs, organic–inorganic composite SSEs, and inorganic (sulfides) SSEs) are systemically reviewed, respectively. Moreover, the progress for promising inorganic (sulfides) SSE‐based Si‐SSBs on the aspects of electrode constitution, three‐dimensional structured electrodes, and external stack pressure is highlighted, respectively. Finally, future research directions and prospects in the development of Si‐SSBs are proposed.

High-voltage non-aqueous lithium metal batteries suffer from poor cycling stability due to the presence of impurities in the electrolyte solution. Here, the authors report lithium hexamethyldisilazide to scavenge HF and H2O, prevent the Ni dissolution and suppress side reactions during cycling.

While water splitting in acid offers higher operational performances than in alkaline conditions, there are few high-activity, acid-stable oxygen evolution electrocatalysts. Here, authors examine electrochemical Li intercalation to improve the activity and stability of RuO2 for acidic water oxidation.

Carbon materials are key components in energy storage and conversion devices and most directly impact device performance. The need for advanced carbon materials has become more pressing with the increasing demand for high-performance energy conversion and storage facilities. Nonetheless, realizing significant performance improvements across devices remains challenging because of the difficulties in controlling irregularly organized microstructures and the specific carbon structures concerned. With the aim of realizing devisable structures, adjustable functions, and performance breakthroughs, this review proposes the concept of superstructured carbons. In fact, superstructured carbons are a category of carbon-based materials characterized by precisely built pores, networks, and interfaces. This unique category meets the particular functional demands of high-performance devices and exceeds the rigid structure of traditional carbons. In the context of these superstructured carbons, we present methods for realizing both custom-built structures and target-oriented functionalities. For specific energy-related reactions, we emphasize the targeted property-structure relationships in these well-defined superstructured carbons. Finally, future developments and practicability challenges of superstructured carbons are also proposed.

Solid-state lithium batteries are flourishing due to their excellent potential energy density. Substantial efforts have been made to improve their electrochemical performance by increasing the conductivity of solid-state electrolytes (SEs) and designing a compatible battery configuration. The safety of a solid lithium battery has generally been taken for granted due to the nonflammability and strength of SEs. However, recent results have shown the release of dangerous gases and intense heat due to the formation of lithium dendrites, indicating the safety of solid-state lithium batteries may have been overestimated. In this review, we introduce a safety evaluation methodology, then focus on the garnet Li7La3Zr2O12 (LLZO) and sulfide-based SEs, summarizing their structure, conductivity, compatibility with a lithium metal anode, electrochemical/chemical stability, and mechanical/thermal stability, which correlate closely with battery safety. We also evaluate the safety of all-solid-state lithium batteries, then conclude by discussing future avenues for improving the safety of SE-based batteries.

Abstract The low initial Coulombic efficiency (ICE) is a significant problem hindering the practical uses of carbon anodes in sodium‐ion batteries (SIBs), especially for the carbons with large surface area. Presodiation is an effective way to solve the above problem, but it always needs complicated operations and cannot suppress the unavoidable electrolyte decomposition in the assembled battery. Herein, we develop an ultrafast chemical presodiation method for reduced graphene oxide (rGO) using sodium naphthalene (Na‐Nt) dissolved in dimethoxyethane (DME) solvent as a presodiation reagent. The presodiation effectively improves the ICE of rGO to 96.8% and forms an artificial solid electrolyte interphase (SEI) on its surface due to the decomposition of the formed complex between Na+ and DME. The formed artificial SEI suppresses the excessive decomposition of electrolytes in the assembled battery, leading to a formation of uniform and inorganic component–rich SEI on rGO surface, which enables a rapid interfacial ion transfer. Therefore, the presodiated rGO showed excellent rate performance with a high capacity of 198.5 mAh g−1 at 5 A g−1. Moreover, excellent cycle stability indicated by the high capacity retention of 68.4% over 1000 cycles was also achieved, showing the potential to promote the practical uses of high‐rate rGO anode in SIBs.

Abstract The replacement of liquid organic electrolytes with solid‐state electrolytes (SSEs) is a feasible way to solve the safety issues and improve the energy density of lithium batteries. Developing SSEs materials that can well match with high‐voltage cathodes and lithium metal anode is quite significant to develop high‐energy‐density lithium batteries. Li1 + xAlxTi2 ‐ x(PO4)3 (LATP) SSE with NASICON structure exhibits high ionic conductivity, low cost and superior air stability, which enable it as one of the most hopeful candidates for all‐solid‐state batteries (ASSBs). However, the high interfacial impedance between LATP and electrodes, and the severe interfacial side reactions with the lithium metal greatly limit its applications in ASSBs. This review introduces the crystal structure and ion transport mechanisms of LATP and summarizes the key factors affecting the ionic conductivity. The side reaction mechanisms of LATP with Li metal and the promising strategies for optimizing interfacial compatibility are reviewed. We also summarize the applications of LATP including as surface coatings of cathode particles, ion transport network additives and inorganic fillers of composite polymer electrolytes. At last, this review proposes the challenges and the future development directions of LATP in SSBs.

Abstract Security risks of flammability and explosion represent major problems with the use of conventional lithium rechargeable batteries using a liquid electrolyte. The application of solid‐state electrolytes could effectively help to avoid these safety concerns. However, integrating the solid‐state electrolytes into the all‐solid‐state lithium batteries is still a huge challenge mainly due to the high interfacial resistance present in the entire battery, especially at the interface between the cathode and the solid‐state electrolyte pellet and the interfaces inside the cathode. Herein, recent progress made from investigations of cathode/solid‐state electrolyte interfacial behaviors including the contact problem, the interlayer diffusion issue, the space‐charge layer effect, and electrochemical compatibility is presented according to the classification of oxide‐, sulfide‐, and polymer‐based solid‐state electrolytes. We also propose strategies for the construction of ideal next‐generation cathode/solid‐state electrolyte interfaces with high room‐temperature ionic conductivity, stable interfacial contact during long cycling, free formation of the space‐charge region, and good compatibility with high‐voltage cathodes.

Abstract Lithium sulfide (Li2S) is a promising cathode for a practical lithium‐sulfur battery as it can be coupled with various safe lithium‐free anodes. However, the high activation potential (>3.5 V) together with the shuttling of lithium polysulfides (LiPSs) bottleneck its practical uses. We are trying to present a catalysis solution to solve both problems simultaneously, specially with twinborn heterostructure to shoot off the trouble in interfacial contact between two solids, catalyst and Li2S. As a typical example, a Co9S8/Li2S heterostructure is reported here as a novel self‐catalytic cathode through a co‐recrystallization followed by a one‐step carbothermic conversion. Co9S8 as the catalyst effectively lowers the Li2S activation potential (

Composite solid-state electrolytes have received significant attention due to their combined advantages as inorganic and polymer electrolytes. However, conventional ceramic fillers offer limited ion conductivity enhancement for composite solid-state electrolytes due to the space-charge layer between the polymer matrix and ceramic phase. In this study, we develop a ferroelectric ceramic ion conductor (LiTaO3) as a functional filler to simultaneously alleviate the space-charge layer and provide an extra Li+ transport pathway. The obtained composite solid-state electrolyte comprising LiTaO3 filler and poly (vinylidene difluoride) matrix (P-LTO15) achieves an ionic conductivity of 4.90 × 10−4 S cm−1 and a Li+ transference number of 0.45. The polarized ferroelectric LiTaO3 creates a uniform electric field and promotes homogenous Li plating/stripping, providing the Li symmetrical batteries with an ultrastable cycle life for 4000 h at 0.1 mA cm−2 and a low polarization overpotential (~50 mV). Furthermore, the solid-state NCM811/P-LTO15/Li full batteries achieve an ultralong cycling performance (1400 cycles) at 1 C and a high discharge capacity of 102.1 mAh g−1 at 5 C. This work sheds light on the design of functional ceramic fillers for composite solid-state electrolytes to effectively enhance ion conductivity and battery performance.

Abstract LiNi0.8Co0.15Al0.05O2 (NCA) secondary particles with high tap density have a great potential for high volumetric energy density lithium (Li)‐ion power battery. However, the ionic conductivity mechanism of NCA with compact structure is still a suspense, especially the function of grain boundaries. Herein, we systematically investigate the Li‐ion transport behavior in both the primitive NCA (PNCA) secondary sphere densely grown by single‐crystal primary grains and ball‐milled NCA (MNCA) nanosized particle to reveal the role of grain boundaries for Li‐ion transport. The PNCA and MNCA have comparable Li‐ion diffusion coefficients and rate performance. Moreover, the graphene nanosheet conductive additive only mildly affects the Li‐ion diffusion in PNCA cathode, while which severely blocks the Li‐ion transport in MNCA cathode. Through high‐resolution transmission electron microscopy and electron energy loss spectroscopy, we clearly observe Li‐ion depletion at lower state of charge (SOC) and Li‐ion aggregation at high SOC along the grain boundaries of PNCA secondary particles during high‐rate lithiation process. The grain boundaries can construct an interconnected Li‐ion transport network for highly efficient Li‐ion transport, which contributes to excellent high‐rate performance of compact PNCA secondary particles. These findings present new strategy and deep insight in designing compact materials with excellent high‐rate performance.

Abstract Li is an ideal anode material for use in state‐of‐the‐art secondary batteries. However, Li‐dendrite growth is a safety concern and results in low coulombic efficiency, which significantly restricts the commercial application of Li secondary batteries. Unfortunately, the Li‐deposition (growth) mechanism is poorly understood on the atomic scale. Here, machine learning is used to construct a Li potential model with quantum‐mechanical computational accuracy. Molecular dynamics simulations in this study with this model reveal two self‐healing mechanisms in a large Li‐metal system, viz. surface self‐healing, and bulk self‐healing. It is concluded that self‐healing occurs rapidly in nanoscale; thus, minimizing the voids between the Li grains using several comprehensive methods can effectively facilitate the formation of dendrite‐free Li.

The inner constituents of lithium-ion batteries (LIBs) are easy to deform during charging and discharging processes, and the accumulation of these deformations would result in physical fractures, poor safety performances, and short lifespan of LIBs. Recent studies indicate that the introduction of self-healing (SH) materials into electrodes or electrolytes can bring about great enhancements in their mechanical strength, thus optimizing the cycle stability of the batteries. Due to the self-healing property of these special functional materials, the fractures/cracks generated during repeated cycles could be spontaneously cured. This review systematically summarizes the mechanisms of self-healing strategies and introduces the applications of SH materials in LIBs, especially from the aspects of electrodes and electrolytes. Finally, the challenges and the opportunities of the future research as well as the potential of applications are presented to promote the research of this field.

Here the authors show a beta alumina nanowires/gel polymer composite electrolyte design. The dense and homogeneous solid-liquid hybrid sodium-ion transportation channels promote uniform sodium deposition and stripping and significantly improve the performance of a Na metal battery.

Sodium ion batteries are known to benefit from the use of ether electrolytes. Here the authors reveal the origin showing that the energy barrier of charge transfer at the electrolyte/electrode interface dominates the interfacial electrochemical characteristics and is favorably small.

Lithium metal is considered as one of the most promising anode materials for high-energy-density rechargeable batteries. However, uncontrolled dendrite growth, the unstable interface between lithium metal anode and electrolyte, and infinite volume change are major obstacles in their practical applications. Constructing a solid electrolyte interphase (SEI) with high strength, good stability, and desirable flexibility is one of the most promising approaches to mitigate the volume expansion of lithium anode and induce the uniform deposition of lithium for dendrite-free anode. Herein, we summarize the advances of SEI modification from the aspects of in-situ (adding electrolyte additives) and ex-situ (constructing artificial SEI) methods. The ideal SEI on lithium anode can effectively suppress the lithium dendrite growth and volume change of lithium metal anode. In the future study, the modification of SEI should focus on the suppression of side reactions between active lithium metal and electrolyte and the formation of dead lithium, which is quite significant to reduce the consumption of active lithium anode and electrolyte for safe and long-life high energy lithium metal batteries. Constructing an excellent SEI is a robust strategy to achieve the highly stable lithium metal anode for practical application of lithium metal batteries.

Abstract Solid composite electrolytes (SCEs) that combine the advantages of solid polymer electrolytes (SPEs) and inorganic ceramic electrolytes (ICEs) present acceptable ionic conductivity, high mechanical strength, and favorable interfacial contact with electrodes, which greatly improve the electrochemical performance of all‐solid‐state batteries compared to single SPEs and ICEs. However, there are many challenges to overcome before the practical application of SCEs, including the low ionic conductivity less than 10−3 S cm−1 at ambient temperature, poor interfacial stability, and high interfacial resistance, which greatly restrict the room temperature performance. Herein, the advances of SCEs applied in all‐solid‐state lithium batteries are presented, including the Li ion migration mechanism of SCEs, the strategies to enhance the ionic conductivity of SCEs by various morphologies of ICEs, and construction methods of the low resistance and stable interfaces of SCEs with both cathode and anode. Finally, some typical applications of SCEs in lithium batteries are summarized and future development directions are prospected. This work presents how it is quite significant to further enhance the ionic conductivity of SCEs by developing the novel SPEs with the special morphology of ICEs for advanced all‐solid‐state lithium batteries.

Abstract Lithium‐sulfur (Li‐S) batteries are considered as one of the most promising energy storage systems for next‐generation electric vehicles because of their high‐energy density. However, the poor cyclic stability, especially at a high sulfur loading, is the major obstacles retarding their practical use. Inspired by the nacre structure of an abalone, a similar configuration consisting of layered carbon nanotube (CNT) matrix and compactly embedded sulfur is designed as the cathode for Li‐S batteries, which are realized by a well‐designed unidirectional freeze‐drying approach. The compact and lamellar configuration with closely contacted neighboring CNT layers and the strong interaction between the highly conductive network and polysulfides have realized a high sulfur loading with significantly restrained polysulfide shuttling, resulting in a superior cyclic stability and an excellent rate performance for the produced Li‐S batteries. Typically, with a sulfur loading of 5 mg cm−2, the assembled batteries demonstrate discharge capacities of 1236 mAh g−1 at 0.1 C, 498 mAh g−1 at 2 C and moreover, when the sulfur loading is further increased to 10 mg cm−2 coupling with a carbon‐coated separator, a superhigh areal capacity of 11.0 mAh cm−2 is achieved.

In this work, high-level heteroatom doped two-dimensional hierarchical carbon architectures (H-2D-HCA) are developed for highly efficient Li-ion storage applications. The achieved H-2D-HCA possesses a hierarchical 2D morphology consisting of tiny carbon nanosheets vertically grown on carbon nanoplates and containing a hierarchical porosity with multiscale pore size. More importantly, the H-2D-HCA shows abundant heteroatom functionality, with sulfur (S) doping of 0.9% and nitrogen (N) doping of as high as 15.5%, in which the electrochemically active N accounts for 84% of total N heteroatoms. In addition, the H-2D-HCA also has an expanded interlayer distance of 0.368 nm. When used as lithium-ion battery anodes, it shows excellent Li-ion storage performance. Even at a high current density of 5 A g−1, it still delivers a high discharge capacity of 329 mA h g−1 after 1,000 cycles. First principle calculations verifies that such unique microstructure characteristics and high-level heteroatom doping nature can enhance Li adsorption stability, electronic conductivity and Li diffusion mobility of carbon nanomaterials. Therefore, the H-2D-HCA could be promising candidates for next-generation LIB anodes.

The original version of this Article incorrectly omitted an affiliation of Kaikai Li: ‘Shenzhen Environmental Science and New Energy Technology Engineering Laboratory, Tsinghua-Berkeley Shenzhen Institute (TBSI), Tsinghua University, Shenzhen 518055, China’. This has been corrected in both the PDF and HTML versions of the Article.