Hierarchical BiOCl flowerlike microspheres via a room-temperature solid-state chemical reaction as a new anode for rechargeable magnesium-ion batteries.

Rechargeable magnesium-ion batteries (MIBs) have received much attention in recent years, but their development remains limited due to a lack of anode materials with high capacity and fast diffusion kinetics. Herein, for the first time, hierarchical BiOX (X = Cl, Br, I) flowerlike microspheres composed of interleaved nanosheets are constructed via a simple room-temperature solid-state chemical reaction as the anode for MIBs. Among them, BiOCl flowerlike microspheres deliver good cycling stability (110 mA h g-1 after 100 cycles) and a superior rate capacity (134 mA h g-1 at 500 mA g-1). This is attributed to their unique flowerlike microsphere structure that not only accommodates a volume change to maintain their structural integrity but also shortens the ion-transport path to improve the diffusion rate. Importantly, ex situ tests were carried out to clarify the phase and structure evolution of the BiOCl flowerlike microspheres during cycling. The results show that BiOCl is first transformed to Bi and then alloyed to Mg3Bi2 in the discharging process, and Mg3Bi2 is turned back to Bi in the charging process. Besides, the initial microsphere structure is essentially maintained during the discharging/charging process, indicating the better stability of the structure. The current study demonstrates that the structural design of flowerlike microspheres is an effective strategy to develop promising anode materials for MIBs.

High-Energy Aqueous Magnesium Ion Batteries with Capacity-Compensation Evolved from Dynamic Copper Ion Redox.

The low specific capacity and low voltage plateau are significant challenges in the advancement of practical magnesium ion batteries (MIBs). Here, a superior aqueous electrolyte combining with a copper foam interlayer between anode and separator is proposed to address these drawbacks. Notably, with the dynamic redox of copper ions, the weakened solvation of Mg2+ cations in the electrolyte and the enhanced electronic conductivity of anode, which may offer effective capacity-compensation to the 3,4,9,10-perylenetetracarboxylic diimide (PTCDI)-Mg conversion reactions during the long-term cycles. As a result, the unique MIBs using expanded graphite cathode coupled with PTCDI anode demonstrate exceptional performance with an ultra-high capacity (205 mAh g-1 , 243 Wh kg-1 at 5 A g-1 ) as well as excellent cycling stability after 600 cycles and rate capability (138 mAh g-1 , 81 Wh kg-1 at 10 A g-1 ).

Toward High-Performance Mg-S Batteries via a Copper Phosphide Modified Separator.

Magnesium-sulfur (Mg-S) batteries are emerging as a promising alternative to lithium-ion batteries, due to their high energy density and low cost. Unfortunately, current Mg-S batteries typically suffer from the shuttle effect that originates from the dissolution of magnesium polysulfide intermediates, leading to several issues such as rapid capacity fading, large overcharge, severe self-discharge, and potential safety concern. To address these issues, here we harness a copper phosphide (Cu3P) modified separator to realize the adsorption of magnesium polysulfides and catalyzation of the conversion reaction of S and Mg2+ toward stable cycling of Mg-S cells. The bifunctional layer with Cu3P confined in a carbon matrix is coated on a commercial polypropylene membrane to form a porous membrane with high electrolyte wettability and good thermal stability. Density functional theory (DFT) calculations, polysulfide permeability tests, and post-mortem analysis reveal that the catalytic layer can adsorb polysulfides, effectively restraining the shuttle effect and facilitating the reversibility of the Mg-S cells. As a result, the Mg-S cells can achieve a high specific capacity, fast rates (449 mAh g-1 at 0.1 C and 249 mAh g-1 at 1.0 C), and a long cycle life (up to 500 cycles at 0.5 C) and operate even at elevated temperatures.

High-energy silicon-sulfurized poly(acrylonitrile) battery based on a nitrogen evolution reaction.

The practical application of high-energy lithium-sulfur battery is plagued with two deadly obstacles. One is the "shuttle effect" originated from the sulfur cathode, and the other is the low Coulombic efficiency and security issues arising from the lithium metal anode. In addressing these issues, we propose a novel silicon-sulfurized poly(acrylonitrile) full battery. In this lithium metal-free system, the Li source is pre-loaded in the cathode, using a nitrogen evolution reaction (NER) to implant Li+ into the silicon/carbon anode. Sulfurized poly(acrylonitrile) based on a solid-solid conversion mechanism can fundamentally circumvent the "shuttle effect". Meanwhile, the silicon/carbon anode can achieve more efficient utilization and higher security when compared with the Li metal anode. The full cell used in this technology can deliver a capacity of 1169.3 mAh g-1, and it can be stabilized over 100 cycles, implying its excellent electrochemical stability. Furthermore, the practical pouch cell with a high sulfur loading of 4.2 mg cm-2 can achieve a high specific energy of 513.2 Wh kg-1. The mechanism of the NER in cathode has also been investigated and analyzed by in situ methods. Notably, this battery design completely conforms to the current battery production technology because of the degassing of gasbag, resulting in a low manufacturing cost. This work will open the avenue to develop a lithium metal-free battery using the NER.

Empowering Zn Electrode Current Capability Along Interfacial Stability by Optimizing Intrinsic Safe Organic Electrolytes.

Metallic Zn is one of the most promising anodes, but its practical application has been hindered by dendritic growth and serious interfacial reactions in conventional electrolytes. Herein, ionic liquids are adopted to prepare intrinsically safe electrolytes via combining with TEP or TMP solvents. With this synergy effect, the blends of TEP/TMP with an IL fraction of ≈25 wt% are found to be promising electrolytes, with ionic conductivities comparable to those of standard phosphate-based electrolytes while electrochemical stabilities are considerably improved; over 1000 h at 2.0 mA cm-2 and ≈350 h at 5.0 mA cm-2 with a large areal capacity of 10 mAh cm-2 . The use of functionalized IL turns out to be a key factor in enhancing the Zn2+ transport due to the interaction of Zn2+ ions with IL-zincophilic sites resulting in reduced interfacial resistance between the electrodes and electrolyte upon cycling leading to spongy-like highly porous, homogeneous, and dendrite-free zinc as an anode material.

Insights into the stability of magnesium borate salts for rechargeable magnesium batteries from AIMD simulations.

We present AIMD simulations for the stability of boron-center salts, Mg[B(Ohfip)4]2 and Mg[B(Otfe)4]2, compared to Mg(TFSI)2, and provide a visible reaction process at the atomic level. -CF3 groups have a positive effect on the electrochemical performance, and C atoms do not easily fall off from the anion groups to form a SEI in Mg[B(Ohfip)4]2, which will help to find high-performance magnesium electrolytes.

Fe2O3/MoO3@NG Heterostructure Enables High Pseudocapacitance and Fast Electrochemical Reaction Kinetics for Lithium-Ion Batteries.

Transition metal oxides (TMOs) hold great potential for lithium-ion batteries (LIBs) on account of the high theoretical capacity. Unfortunately, the unfavorable volume expansion and low intrinsic electronic conductivity of TMOs lead to irreversible structural degradation, disordered particle agglomeration, and sluggish electrochemical reaction kinetics, which result in perishing rate capability and long-term stability. This work reports an Fe2O3/MoO3@NG heterostructure composite for LIBs through the uniform growth of Fe2O3/MoO3 heterostructure quantum dots (HQDs) on the N-doped rGO (NG). Due to the synergistic effects of the "couple tree"-type heterostructures constructed by Fe2O3 and MoO3 with NG, Fe2O3/MoO3@NG delivers a prominent rate performance (322 mA h g-1 at 20 A g-1, 5.0 times higher than that of Fe2O3@NG) and long-term cycle stability (433.5 mA h g-1 after 1700 cycles at 10 A g-1). Theoretical calculations elucidate that the strong covalent Fe-O-Mo, Mo-N, and Fe-N bonds weaken the diffusion energy barrier and promote the Li+-ion reaction to Fe2O3/MoO3@NG, thereby facilitating the structural stability, pseudocapacitance contribution, and electrochemical reaction kinetics. This work may provide a feasible strategy to promote the practical application of TMO-based LIBs.

Reduced Graphene Oxide (rGO)-Supported and Pyrolytic Carbon (PC)-Coated γ-Fe2 O3 /PC-rGO Composite Anode Material with Enhanced Li Storage Performance.

As a high-capacity anode material for lithium ion batteries, γ-Fe2 O3 is a promising alternative to conventional graphite among multifarious transition metal oxides owing to its high theoretical specific capacity (1007 mAh g-1 ), abundant reserves, good safety and low cost. However, improving the electrical conductivity and overcoming the morphological damage caused by the severe volume expansion during cycling are still the tricky problems to be solved. Herein, a three-dimensional heterostructure composite (γ-Fe2 O3 /PC-rGO60 ) was prepared by a facile solvothermal reaction followed by heat treatment in inert atmosphere. This composite material exhibits a reversible charge specific capacity of 1035 mAh g-1 at the current density of 0.1 A g-1 . After 100 cycles at 0.2 A g-1 , the capacity is increased from 966.2 to 1091.1 mAh g-1 . Even cycled for 200 cycles at 1 A g-1 , the capacity is only decreased from 751.4 to 670.6 mAh g-1 , giving capacity retention of 89.3%. The rGO network supported flexible composite architecture is beneficial for accommodating the volume expansion of the γ-Fe2 O3 active material during the lithiation/delithiation process. Besides, the conductive rGO network and the in-situ formed pyrolytic carbon (PC) can provide a smooth electron transmission path and a favorable lithium ion transport channel.

SnSe2 /FeSe2 Nanocubes Capsulated in Nitrogen-Doped Carbon Realizing Stable Sodium-Ion Storage at Ultrahigh Rate.

Metal selenides have attracted increasing attention recently as anodes for sodium-ion batteries (SIBs) because of their large capacities, high electric conductivity, as well as environmental benignity. However, the application of metal selenides is hindered by the huge volume variation, which causes electrode structure devastation and the consequent degrading cycling stability and rate capability. To overcome the aforementioned obstacles, herein, SnSe2 /FeSe2 nanocubes capsulated in nitrogen-doped carbon (SFS@NC) are fabricated via a facile co-precipitation method, followed by poly-dopamine wrapping and one-step selenization/carbonization procedure. The most remarkable feature of SFS@NC is the ultra-stability under high current density while delivering a large capacity. The synergistic effect of dual selenide components and core-shell architecture mitigates the volume effect, alleviates the agglomeration of nanoparticles, and further improves the electric conductivity. The as-prepared SFS@NC nanocubes present a high capacity of 408.1 mAh g-1 after 1200 cycles at 6 A g-1 , corresponding to an 85.3% retention, and can achieve a capacity of 345.0 mAh g-1 at an extremely high current density of 20 A g-1 . The outstanding performance of SFS@NC may provide a hint to future material structure design strategy, and promote further developments and applications of SIBs.

A Chlorine-Free Electrolyte Based on Non-nucleophilic Magnesium Bis(diisopropyl)amide and Ionic Liquid for Rechargeable Magnesium Batteries.

The electrolyte based on magnesium bis(diisopropyl)amide (MBA), a low-cost and non-nucleophilic organic magnesium salt, is proposed to be an admirable alternative for rechargeable magnesium batteries but suffers from limited ionic conductivity and an inferior electrochemical window in the commonly used ether solvents. In this work, the 1-butyl-1-methylpiperidinium bis(trifluoromethyl sulfonyl)imide (PP14TFSI) ionic liquid as the cosolvent of tetrahydrofuran (THF) in chlorine-free MBA-based electrolytes has been first demonstrated to remarkably improve the ionic conductivity and broaden the oxidative stable potential (2.2 V vs Mg/Mg2+) on stainless steel. Reversible Mg electrochemical plating/stripping with a low overpotential below 200 mV and ca. 90% Coulombic efficiency are obtained. The current density of Mg plating/stripping is increased 238 times after the addition of PP14TFSI, where the mechanism of competitive coordination of TFSI- making an easier Mg plating/stripping is proposed theoretically. The MBA-2AlF3 electrolyte with a ratio-optimized THF/PP14TFSI cosolvent exhibits good compatibility with the Mo6S8 cathode. Furthermore, the Se@pPAN|Mg full cell exhibits an initial capacity of 447.8 mAh g-1 and as low as ∼0.66% capacity decay per cycle for more than 70 cycles at 0.2 C with the synergy of LiTFSI additives. The facile modification strategy of ionic liquid in the MBA-based electrolyte sheds inspiring light on exploring non-nucleophilic and chlorine-free electrolytes for practical rechargeable magnesium batteries.

Coupling-Agent-Coordinated Uniform Polymer Coating on LiNi0.6Co0.2Mn0.2O2 for Improved Electrochemical Performance at Elevated Temperatures.

The high-voltage Ni-rich LiNixCoyMnzO2 cathode materials attract attention due to their high capacity and relatively low cost. However, the undesired instability originating from side reactions with liquid electrolytes at elevated temperatures still hinders their practical application. This research aims to build a stable interface between cathode and electrolyte. We use the coupling agent KH570 to induce vinyl ethylene carbonate (VEC) monomers to in situ polymerize on the surface of LiNi0.6Co0.2Mn0.2O2 (NCM622) to form a uniform, ultrathin (∼12 nm), and highly ion-conductive poly(vinyl ethylene carbonate) (PVEC) solid polymer electrolyte layer. The modified cathode material exhibits significant improvement in rate performance and cycling stability up to 4.5 V at elevated temperatures. Scanning electron microscopy and X-ray diffraction techniques prove that the flexible polymer coating layer effectively suppresses the mechanical degradation and crystal structure changes during cycling.

ENLARGED STARCH GRAIN1 affects amyloplast development and starch biosynthesis in rice endosperm.

Cereal crops accumulate large amounts of starch which is synthesized and stored in amyloplasts in the form of starch grains (SGs). Despite significant progress in deciphering starch biosynthesis, our understanding of amyloplast development in rice (Oryza sativa) endosperm remains largely unknown. Here, we report a novel rice floury mutant named enlarged starch grain1 (esg1). The mutant has decreased starch content, altered starch physicochemical properties, slower grain-filling rate and reduced 1000-grain weight. A distinctive feature in esg1 endosperm is that SGs are much larger, mainly due to an increased number of starch granules per SG. Spherical and loosely assembled granules, together with those weakly stained SGs may account for decreased starch content in esg1. Map-based cloning revealed that ESG1 encodes a putative permease subunit of a bacterial-type ABC (ATP-binding cassette) lipid transporter. ESG1 is constitutively expressed in various tissues. It encodes a protein localized to the chloroplast and amyloplast membranes. Mutation of ESG1 causes defective galactolipid synthesis. The overall study indicates that ESG1 is a newly identified protein affecting SG development and subsequent starch biosynthesis, which provides novel insights into amyloplast development in rice.

An Antipulverization and High-Continuity Lithium Metal Anode for High-Energy Lithium Batteries.

Lithium metal is one of the most promising anode candidates for next-generation high-energy batteries. Nevertheless, lithium pulverization and associated loss of electrical contact remain significant challenges. Here, an antipulverization and high-continuity lithium metal anode comprising a small number of solid-state electrolyte (SSE) nanoparticles as conformal/sacrificial fillers and a copper (Cu) foil as the supporting current collector is reported. Guiding by the SSE, this new anode facilitates lithium nucleation, contributing to form a roundly shaped, micro-sized, and dendrite-free electrode during cycling, which effectively mitigates the lithium dendrite growth. The embedded Cu current collector in the hybrid anode not only reinforces the mechanical strength but also improves the efficient charge transfer among active lithium filaments, affording good electrode structural integrity and electrical continuity. As a result, this antipulverization and high-continuity lithium anode delivers a high average Coulombic efficiency of ≈99.6% for 300 cycles under a current density of 1 mA cm-2 . Lithium-sulfur batteries (elemental sulfur or sulfurized polyacrylonitrile cathodes) equipped with this anode show high-capacity retentions in their corresponding ether-based or carbonate-based electrolytes, respectively. This new electrode provides important insight into the design of electrodes that may experience large volume variation during operations.

A Novel Filler for Gel Polymer Electrolyte with a High Lithium-Ion Transference Number toward Stable Cycling for Lithium-Metal Anodes in Lithium-Sulfur Batteries.

Although the lithium metal is considered as the most promising anode for high energy density batteries, uncontrolled lithium dendrite growth and continuous side reactions with electrolyte hinder its practical applications for rechargeable batteries. Herein, we prepared a gel polymer electrolyte by synthesizing a novel 250 nm filler (KMgF3), which is greatly beneficial to the formation of a uniformly deposited lithium-metal anode. This is due to the regulation effect of KMgF3 that double the lithium-ion transference number up to 0.63 and adjust the solid electrolyte interphase layer full of dense LiF and flexible polycarbonates, which greatly reduces the side reactions on the lithium-metal surface and inhibits the growth of lithium dendrites. Consequently, the composite gel polymer electrolyte guarantees a stable long cycle performance of more than 1400 h with 1 mA h cm-2 for symmetric cells. Moreover, the composite gel polymer electrolyte demonstrates high compatibility and great promise for rechargeable lithium-sulfur (Li-S) batteries.

High Molecular Weight Polyacrylonitrile Precursor for S@pPAN Composite Cathode Materials with High Specific Capacity for Rechargeable Lithium Batteries.

Sulfurized pyrolyzed poly(acrylonitrile) (S@pPAN) demonstrates high sulfur utilization, no polysulfide dissolution, no self-discharge, and extremely stable cycling. Its precursor, PAN, directly determines the performances of cathode materials, including the sulfur content and its utilization for S@pPAN composite materials. Adopting PAN with the molecular weight approaching 550,000 as the precursor, the sulfur content in S@pPAN approaches 55 wt %, and its reversible specific capacity was 901 mAh g-1(composite) at 50 °C with sulfur utilization over 98%. Moreover, it enabled stable cycling and excellent high rate capability with a specific capacity of 645 mAh g-1 at 5 C. These significantly enhanced electrochemical properties are mainly due to the high molecular weight of the PAN precursor, which provides more space to accommodate amorphous sulfur, along with improved interfacial resistance of S@pPAN.

Stable Lithium Metal Anode Enabled by a Lithiophilic and Electron/Ion Conductive Framework.

Li metal anode has been considered as the ideal anode for next-generation batteries due to its ultrahigh capacity and lowest electrochemical potential. However, its practical application is still impeded by low Coulombic efficiency, huge volume change, and safety hazards arising from Li dendrite growth. In this work, a three-dimensional (3D) structured highly stable Li metal anode is designed and easily preapred. Benefiting from the in situ reaction between Li metal and AlN, highly Li+ conductive Li3N and lithiophilic LiAl alloy have been simultaneously formed and homogeneously distributed in the framework, in which Li metal is finely dispersed and embedded. The outstanding electron/ion mixed conductivity of Li3N/LiAl and 3D composite structure with enhanced interfacial area significantly improve the electrode kinetics and suppress the volume change on cycling, while a lithiophilic effect of LiAl alloy and uniform distribution of Li ion flux inside the electrode avoid dendritic Li deposition. As a result, the proposed Li metal electrode exhibits exceptional electrochemical reversibility in both carbonate and ether-based electrolytes. Paired with LiFePO4 and sulfurized polyacrylonitrile (S@pPAN) cathodes, the full cells deliver highly stable and long-term cycling performance. Therefore, the proposed strategy to fabricate Li metal anodes could promote the practical application of Li metal batteries.

Prospect of Sulfurized Pyrolyzed Poly(acrylonitrile) (S@pPAN) Cathode Materials for Rechargeable Lithium Batteries.

Lithium-sulfur (Li-S) batteries are one of the most promising next-generation batteries owing to their ultra-high theoretical energy density and that sulfur is an abundant resource. During the past 20 years, various sulfur materials have been reported. As a molecular-scale sulfur-composite cathode, sulfurized pyrolyzed poly(acrylonitrile) (S@pPAN) exhibits several competitive advantages in terms of its electrochemical behavior. Although it was first reported in 2002 S@pPAN is currently attracting increasing attention. In this Minireview, we summarize its molecular model and explore the correlation between its structure and its exceptional electrochemical performance. We classify the modification strategies into three types, including material improvement, binder, and electrolyte screening. Several research and development directions are also suggested.

Small Grain and Dwarf 2, encoding an HD-Zip II family transcription factor, regulates plant development by modulating gibberellin biosynthesis in rice.

Homeodomain leucine zipper (HD-Zip) proteins are transcription factors that regulate plant development. Bioactive gibberellin (GA) is a key endogenous hormone that participates in plant growth. However, the relationship between HD-Zip genes and modulation of GA biosynthesis in rice remains elusive. Here, we identified a rice mutant, designated as small grain and dwarf 2 (sgd2), which had reduced height and grain size compared with the wild type. Cytological observations indicated that the defective phenotype was mainly due to decreased cell length. Map-based cloning and complementation tests demonstrated that a 9 bp deletion in a homeodomain leucine zipper (HD-Zip) II family transcription factor was responsible for the sgd2 mutant phenotype. Expression of SGD2 was pronounced in developing panicles, and its protein was localized in nucleus. Luciferase reporter system and transactivation assays in yeast suggested that SGD2 functioned as a transcriptional repressor. High performance liquid chromatography assays showed that the endogenous GA1 level in the sgd2 mutant was dramatically decreased, and exogenous GA3 recovered the second leaf sheath to normal length. Results of qRT-PCR showed that the expression levels of genes positively regulating GA-biosynthesis were mostly down-regulated in the mutant. Our data identified the role of an HD-Zip transcription factor that affects rice plant development by modulating gibberellin biosynthesis.

A cyclic nucleotide-gated channel mediates cytoplasmic calcium elevation and disease resistance in rice.

The transient elevation of cytoplasmic calcium is essential for pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI). However, the calcium channels responsible for this process have remained unknown. Here, we show that rice CDS1 (CELL DEATH and SUSCEPTIBLE to BLAST 1) encoding OsCNGC9, a cyclic nucleotide-gated channel protein, positively regulates the resistance to rice blast disease. We show that OsCNGC9 mediates PAMP-induced Ca2+ influx and that this event is critical for PAMPs-triggered ROS burst and induction of PTI-related defense gene expression. We further show that a PTI-related receptor-like cytoplasmic kinase OsRLCK185 physically interacts with and phosphorylates OsCNGC9 to activate its channel activity. Our results suggest a signaling cascade linking pattern recognition to calcium channel activation, which is required for initiation of PTI and disease resistance in rice.

Highly Reversible Lithium-Metal Anode and Lithium-Sulfur Batteries Enabled by an Intrinsic Safe Electrolyte.

Rechargeable lithium-metal batteries have gained significant attention as potential candidates of energy storage systems; however, severe safety issues including flammable electrolyte and dendritic lithium formation hinder their further practical application. In this work, we develop a novel intrinsic flame-retardant electrolyte, which enables a stable and dendrite-free cycling with lithium plating/stripping Coulombic efficiency of up to 99.1% over 500 cycles. Raman spectra indicate that no free molecular solvent exists, and X-ray photoelectron spectroscopy reveals the LiF-rich interphase on the Li-metal anode. When coupled with sulfurized pyrolyzed poly(acrylonitrile) cathode, it shows a benign electrochemical reversibility with the areal capacity of up to 3.41 mAh cm-2 after 70 cycles. To further check its compatibility with sulfur cathode, a higher sulfur content (51.6%) is examined with the areal capacity of 3.92 mAh cm-2 and sulfur utilization of 81.7%. This work provides an alternative for safe and high-performance Li-S batteries via a novel electrolyte strategy.