Amorphous Oxyhalide Matters for Achieving Lithium Superionic Conduction.

The recently surged halide-based solid electrolytes (SEs) are great candidates for high-performance all-solid-state batteries (ASSBs), due to their decent ionic conductivity, wide electrochemical stability window, and good compatibility with high-voltage oxide cathodes. In contrast to the crystalline phases in halide SEs, amorphous components are rarely understood but play an important role in Li-ion conduction. Here, we reveal that the presence of amorphous component is common in halide-based SEs that are prepared via mechanochemical method. The fast Li-ion migration is found to be associated with the local chemistry of the amorphous proportion. Taking Zr-based halide SEs as an example, the amorphization process can be regulated by incorporating O, resulting in the formation of corner-sharing Zr-O/Cl polyhedrons. This structural configuration has been confirmed through X-ray absorption spectroscopy, pair distribution function analyses, and Reverse Monte Carlo modeling. The unique structure significantly reduces the energy barriers for Li-ion transport. As a result, an enhanced ionic conductivity of (1.35 ± 0.07) × 10-3 S cm-1 at 25 °C can be achieved for amorphous Li3ZrCl4O1.5. In addition to the improved ionic conductivity, amorphization of Zr-based halide SEs via incorporation of O leads to good mechanical deformability and promising electrochemical performance. These findings provide deep insights into the rational design of desirable halide SEs for high-performance ASSBs.

A Dual Anion Chemistry-Based Superionic Glass Enabling Long-Cycling All-Solid-State Sodium-Ion Batteries.

Glassy Na-ion solid-state electrolytes (GNSSEs) are an important group of amorphous SSEs. However, the insufficient ionic conductivity of state-of-the-art GNSSEs at room temperature lessens their promise in the development of all-solid-state Na-ion batteries (ASSNIBs) with high energy density and improved safety. Here we report the discovery of a new sodium superionic glass, 0.5Na2 O2 -TaCl5 (NTOC), based on dual-anion sublattice of oxychlorides. The unique local structures with abundant bridging and non-bridging oxygen atoms contributes to a highly disordered Na-ion distribution as well as low Na+ migration barrier within NTOC, enabling an ultrahigh ionic conductivity of 4.62 mS cm-1 at 25 °C (more than 20 times higher than those of previously reported GNSSEs). Moreover, the excellent formability of glassy NTOC electrolyte and its high electrochemical oxidative stability ensure a favourable electrolyte-electrode interface, contributing to superior cycling stability of ASSNIBs for over 500 cycles at room temperature. The discovery of glassy NTOC electrolyte would reignite research enthusiasm in superionic glassy SSEs based on multi-anion chemistry.

Reviving Cost-Effective Organic Cathodes in Halide-Based All-Solid-State Lithium Batteries.

The evolution of inorganic solid electrolytes has revolutionized the field of sustainable organic cathode materials, particularly by addressing the dissolution problems in traditional liquid electrolytes. However, current sulfide-based all-solid-state lithium-organic batteries still face challenges such as high working temperatures, high costs, and low voltages. Here, we design an all-solid-state lithium battery based on a cost-effective organic cathode material phenanthrenequinone (PQ) and a halide solid electrolyte Li2ZrCl6. Thanks to the good compatibility between PQ and Li2ZrCl6, the PQ cathode achieved a high specific capacity of 248 mAh g-1 (96 % of the theoretical capacity), a high average discharge voltage of 2.74 V (vs. Li+/Li), and a good capacity retention of 95 % after 100 cycles at room temperature (25 °C). Furthermore, the interactions between the high-voltage carbonyl PQ cathode and both sulfide and halide solid electrolytes, as well as the redox mechanism of the PQ cathode in all-solid-state batteries, were carefully studied by a variety of advanced characterizations. We believe such a design and the corresponding investigations into the underlying chemistry give insights for the further development of practical all-solid-state lithium-organic batteries.

Hopping Rate and Migration Entropy as the Origin of Superionic Conduction within Solid-State Electrolytes.

Inorganic solid-state electrolytes (SSEs) have gained significant attention for their potential use in high-energy solid-state batteries. However, there is a lack of understanding of the underlying mechanisms of fast ion conduction in SSEs. Here, we clarify the critical parameters that influence ion conductivity in SSEs through a combined analysis approach that examines several representative SSEs (Li3YCl6, Li3HoCl6, and Li6PS5Cl), which are further verified in the xLiCl-InCl3 system. The scaling analysis on conductivity spectra allowed the decoupled influences of mobile carrier concentration and hopping rate on ionic conductivity. Although the carrier concentration varied with temperature, the change alone cannot lead to the several orders of magnitude difference in conductivity. Instead, the hopping rate and the ionic conductivity present the same trend with the temperature change. Migration entropy, which arises from lattice vibrations of the jumping atoms from the initial sites to the saddle sites, is also proven to play a significant role in fast Li+ migration. The findings suggest that the multiple dependent variables such as the Li+ hopping frequency and migration energy are also responsible for the ionic conduction behavior within SSEs.

Superionic Conducting Halide Frameworks Enabled by Interface-Bonded Halides.

The revival of ternary halides Li-M-X (M = Y, In, Zr, etc.; X = F, Cl, Br) as solid-state electrolytes (SSEs) shows promise in realizing practical solid-state batteries due to their direct compatibility toward high-voltage cathodes and favorable room-temperature ionic conductivities. Most of the reported superionic halide SSEs have a structural pattern of [MCl6]x- octahedra and generate a tetrahedron-assisted Li+ ion diffusion pathway. Here, we report a new class of zeolite-like halide frameworks, SmCl3, for example, in which 1-dimensional channels are enclosed by [SmCl9]6- tricapped trigonal prisms to provide a short jumping distance of 2.08 Å between two octahedra for Li+ ion hopping. The fast Li+ diffusion along the channels is verified through ab initio molecular dynamics simulations. Similar to zeolites, the SmCl3 framework can be grafted with halide species to obtain mobile ions without altering the base structure, achieving an ionic conductivity over 10-4 S cm-1 at 30 °C with LiCl as the adsorbent. Moreover, the universality of the interface-bonding behavior and ionic diffusion in a class of framework materials is demonstrated. It is suggested that the ionic conductivity of the MCl3/halide composite (M = La-Gd) is likely in correlation with the ionic conductivity of the grafted halide species, interfacial bonding, and framework composition/dimensions. This work reveals a potential class of halide structures for superionic conductors and opens up a new frontier for constructing zeolite-like frameworks in halide-based materials, which will promote the innovation of superionic conductor design and contribute to a broader selection of halide SSEs.

Halide Layer Cathodes for Compatible and Fast-Charged Halides-Based All-Solid-State Li Metal Batteries.

Insertion-type compounds based on oxides and sulfides have been widely identified and well-studied as cathode materials in lithium-ion batteries. However, halides have rarely been used due to their high solubility in organic liquid electrolytes. Here, we reveal the insertion electrochemistry of VX3 (X=Cl, Br, I) by introducing a compatible halide solid-state electrolyte with a wide electrochemical stability window. X-ray absorption near-edge structure analyses reveal a two-step lithiation process and the structural transition of typical VCl3 . Fast Li+ insertion/extraction in the layered VX3 active materials and favorable interface guaranteed by the compatible electrode-electrolyte design enables high rate capability and stable operation of all-solid-state Li-VX3 batteries. The findings from this study will contribute to developing intercalation insertion electrochemistry of halide materials and exploring novel electrode materials in viable energy storage systems.

Genome-wide identification, phylogeny and expression analysis of AP2/ERF transcription factors family in sweet potato.

BACKGROUND: In recent years, much attention has been given to AP2/ERF transcription factors because they play indispensable roles in many biological processes, such as plant development and biotic and abiotic stress responses. Although AP2/ERFs have been thoroughly characterised in many plant species, the knowledge about this family in the sweet potato, which is a vital edible and medicinal crop, is still limited. In this study, a comprehensive genome-wide investigation was conducted to characterise the AP2/ERF gene family in the sweet potato. RESULTS: Here, 198 IbAP2/ERF transcription factors were obtained. Phylogenetic analysis classified the members of the IbAP2/ERF family into three groups, namely, ERF (172 members), AP2 (21 members) and RAV (5 members), which was consistent with the analysis of gene structure and conserved protein domains. The evolutionary characteristics of these IbAP2/ERF genes were systematically investigated by analysing chromosome location, conserved protein motifs and gene duplication events, indicating that the expansion of the IbAP2/ERF gene family may have been caused by tandem duplication. Furthermore, the analysis of cis-acting elements in IbAP2/ERF gene promoters implied that these genes may play crucial roles in plant growth, development and stress responses. Additionally, the available RNA-seq data and quantitative real-time PCR (qRT-PCR) were used to investigate the expression patterns of IbAP2/ERF genes during sweet potato root development as well as under multiple forms of abiotic stress, and we identified several developmental stage-specific and stress-responsive IbAP2/ERF genes. Furthermore, g59127 was differentially expressed under various stress conditions and was identified as a nuclear protein, which was in line with predicted subcellular localization results. CONCLUSIONS: This study originally revealed the characteristics of the IbAP2/ERF superfamily and provides valuable resources for further evolutionary and functional investigations of IbAP2/ERF genes in the sweet potato.

Progress on Lithium Dendrite Suppression Strategies from the Interior to Exterior by Hierarchical Structure Designs.

Lithium (Li) metal is promising for high energy density batteries due to its low electrochemical potential (-3.04 V) and high specific capacity (3860 mAh g-1 ). However, the safety issues impede the commercialization of Li anode batteries. In this work, research of hierarchical structure designs for Li anodes to suppress Li dendrite growth and alleviate volume expansion from the interior (by the 3D current collector and host matrix) to the exterior (by the artificial solid electrolyte interphase (SEI), protective layer, separator, and solid state electrolyte) is concluded. The basic principles for achieving Li dendrite and volume expansion free Li anode are summarized. Following these principles, 3D porous current collector and host matrix are designed to suppress the Li dendrite growth from the interior. Second, artificial SEI, the protective layer, and separator as well as solid-state electrolyte are constructed to regulate the distribution of current and control the Li nucleation and deposition homogeneously for suppressing the Li dendrite growth from exterior of Li anode. Ultimately, this work puts forward that it is significant to combine the Li dendrite suppression strategies from the interior to exterior by 3D hierarchical structure designs and Li metal modification to achieve excellent cycling and safety performance of Li metal batteries.

Manipulating Li2S2/Li2S mixed discharge products of all-solid-state lithium sulfur batteries for improved cycle life.

All-solid-state lithium-sulfur batteries offer a compelling opportunity for next-generation energy storage, due to their high theoretical energy density, low cost, and improved safety. However, their widespread adoption is hindered by an inadequate understanding of their discharge products. Using X-ray absorption spectroscopy and time-of-flight secondary ion mass spectrometry, we reveal that the discharge product of all-solid-state lithium-sulfur batteries is not solely composed of Li2S, but rather consists of a mixture of Li2S and Li2S2. Employing this insight, we propose an integrated strategy that: (1) manipulates the lower cutoff potential to promote a Li2S2-dominant discharge product and (2) incorporates a trace amount of solid-state catalyst (LiI) into the S composite electrode. This approach leads to all-solid-state cells with a Li-In alloy negative electrode that deliver a reversible capacity of 979.6 mAh g-1 for 1500 cycles at 2.0 A g-1 at 25 °C. Our findings provide crucial insights into the discharge products of all-solid-state lithium-sulfur batteries and may offer a feasible approach to enhance their overall performance.

Rich Heterointerfaces Enabling Rapid Polysulfides Conversion and Regulated Li2S Deposition for High-Performance Lithium-Sulfur Batteries.

The practical uses of lithium-sulfur batteries are greatly restricted by the sluggish reaction kinetics of lithium polysulfides (LiPSs), leading to low sulfur utilization and poor cyclic stability. Using the heterostructure catalysts is an effective way to solve the above problems, but how to further enhance the conversion efficiency and avoid the surface passivation by the insulative Li2S has not been well investigated. Herein, a heterostructure catalyst with rich heterointerfaces was prepared by modifying Mo2N microbelt with SnO2 nanodots. The formed rich interfaces with high accessibility act as the profitable nucleation sites guiding the Li2S 3D growth, which avoids the catalyst surface passivation and facilitates the LiPS conversion. The introduction of SnO2 nanodots also enhances the LiPS adsorption. Thus, the assembled battery with the above catalyst as the cathode additive shows a high capacity of 738.3 mAh g-1 after 550 cycles at 0.5 C with an ultralow capacity decay of 0.025% per cycle. Even with high sulfur loading of 9.0 mg cm-2, good cyclic stability is also achieved at 0.5 C with a low E/S ratio of 5 µL mgs-1. This work shows an effective way to enhance the LiPS conversion kinetics and guide Li2S deposition in Li-S batteries.

Electron and Ion Co-Conductive Catalyst Achieving Instant Transformation of Lithium Polysulfide towards Li2 S.

Most of the catalysts in lithium sulfur (Li-S) batteries present low electronic conductivity and the lithium polysulfides (LiPSs) must diffuse onto the surface of the carbon materials to achieve their conversion reaction. It is a significant challenge to achieve the instantaneous transformation of LiPSs to Li2 S in Li-S batteries to suppress the shuttle effect of LiPSs. Herein, a unique electron and ion co-conductive catalyst of carbon-coated Li1.4 Al0.4 Ti1.6 (PO4 )3 (C@LATP) is developed, which not only possesses strong adsorption to LiPSs, but, more importantly, also promotes the instantaneous conversion reaction of LiPSs to Li2 S. The C@LATP nanoparticles as catalytic active sites can synchronously and efficiently provide both Li ions and electrons to facilitate the conversion reaction of LiPSs. The conversion reaction path of LiPSs using C@LATP changes from traditional "adsorption-diffusion-conversion" to novel "adsorption-conversion," which effectively lowers the decomposition barrier of Li2 S6 and promotes faster conversion of LiPSs. The shuttle effect of LiPSs is considerably suppressed and utilization of sulfur is greatly improved. The Li-S batteries using C@LATP present excellent rate, cycling, and self-discharge properties. This work highlights the significance of electron and ion co-conductive solid-state electrolytes for the instantaneous transformation of LiPSs in advanced Li-S batteries.

Integrated Structure of Cathode and Double-Layer Electrolyte for Highly Stable and Dendrite-Free All-Solid-State Li-Metal Batteries.

All-solid-state batteries have become the most potential next-generation energy-storage devices. However, it is quite difficult to simultaneously achieve a single solid-state electrolytes (SSEs) layer with both dendrite-free Li metal plating and low interfacial resistance between the cathode and SSEs. Herein, an integrated structure of cathode and double-layer solid electrolyte membrane (IS-CDL) is designed, which greatly improves the interfacial contact and suppresses the Li dendrite growth. The first "polymer in ceramic" solid electrolyte layer (SL1) consists of 80 wt % Li1.4Al0.4Ti1.6(PO4)3 (LATP) nanoparticles and 20 wt % polyethylene oxide (PEO), and the second polymer electrolyte layer is PEO-based solid electrolyte layer (SL2). The SL1 with high mechanical properties can hinder the growth of Li dendrites and reduce the interfacial resistance with the cathode. The SL2 can inhibit the side reaction between the Li metal and LATP. The Li symmetric cells with sandwich-type hierarchical electrolyte (SL2/SL1/SL2) can stably cycle over 3200 h at 0.1 mA cm-2 at 45 °C. The obtained all-solid-state LiFePO4-IS-CDL/Li batteries present a capacity of 142.6 mA h g-1 at 45 °C with the capacity retention of 91.7% after 100 cycles, and all-solid-state NCM811-IS-CDL/Li batteries deliver a specific capacity of 175.5 mA h g-1 at 60 °C. This work proposes an effective strategy to fabricate all-solid-state lithium batteries with high electrochemical performance.

Cross-linked beta alumina nanowires with compact gel polymer electrolyte coating for ultra-stable sodium metal battery.

Sodium metal batteries have potentially high energy densities, but severe sodium-dendrite growth and side reactions prevent their practical applications, especially at high temperatures. Herein, we design an inorganic ionic conductor/gel polymer electrolyte composite, where uniformly cross-linked beta alumina nanowires are compactly coated by a poly(vinylidene fluoride-co-hexafluoropropylene)-based gel polymer electrolyte through their strong molecular interactions. These  beta alumina nanowires combined with the gel polymer layer create dense and homogeneous solid-liquid hybrid sodium-ion transportation channels through and along the nanowires, which promote uniform sodium deposition and formation of a stable and flat solid electrolyte interface on the sodium metal anode. Side reactions between the sodium metal and liquid electrolyte, as well as sodium dendrite formation, are successfully suppressed, especially at 60 °C. The sodium vanadium phosphate/sodium full cells with composite electrolyte exhibit 95.3% and 78.8% capacity retention after 1000 cycles at 1 C at 25 °C and 60 °C, respectively.