A graphene-like hollow sphere anode for lithium-ion batteries.

We report a flash Joule heating method for the rapid preparation of graphene-like materials. The L-GHS exhibited a uniform diameter of 200 nm and an ideal specific surface area of 670 m2 g-1. Meanwhile, the specific capacity of L-GHS remained at 942 mA h g-1 after 600 cycles (1 A g-1), which shows excellent electrochemical performance.

Iron-doping and facet engineering of NiSe octahedron for synergistically enhanced triiodide reduction activity in photovoltaics.

Reasonable design of cost-effective counter electrode (CE) catalysts for triiodide (I3-) reduction reaction (IRR) by simultaneously combining heteroatom doping and facet engineering is highly desired in iodine-based dye-sensitized solar cells (DSSCs), but really challenging. Herein, the density function theory (DFT) calculations were first conducted to demonstrate that the Fe-doped NiSe (111) showed an appropriate adsorption energy for I3-, increased number of metal active sites, reinforced charge-transfer ability, and strong interaction between 3d states of metal sites and 5p state of I1 atoms in I3-, compared to NiSe (111). Based on this finding, the well-defined Fe-NiSe octahedron with exposed (111) plane (marked as Fe-NiSe (111)) and NiSe octahedron with the same exposed plane (named as NiSe (111)) are controllably synthesized. When the as-prepared Fe-NiSe (111) and NiSe (111) worked as CE catalysts, Fe-NiSe (111) exhibits improved electrochemical performance with higher power conversion efficiency (PCE) than NiSe (111), providing new opportunity to replace precious Pt for DSSCs.

Regulating nitrogen/sulfur terminals on 3D porous Ti3C2 MXene with enhanced reaction kinetics toward high-performance alkali metal ion storage.

In this paper, we have developed a simple and efficient sulfur-amine chemistry strategy to prepare a three-dimensional (3D) porous Ti3C2Tx composite with large amounts of N and S terminal groups. The well-designed 3D macroporous architecture presents enlarged interlayer spacing, large specific surface area, and unique porous structure, which successfully solves the re-stacking issue of MXene during storage and electrode fabrication. It is the amount of concentrated hydrochloric acid added to the S-EDA (ethylenediamine)/MXene colloidal suspension that is critical to the formation of 3D morphology. In addition, N and S terminals on MXene could improve the adsorption ability of K+. Owing to the synergistic effect of the structure design and terminal modification, the N, S codoped three-dimensional porous Ti3C2Tx (3D-NSPM) material shows a high surface capacitive contribution and rapid diffusion kinetics for K+ and Na+. As a result, the as-prepared 3D-NSPM delivers high reversible capacity (237 and 273 mAh g-1 at 0.1 A g-1 for PIBs and SIBs, respectively), superb cycling stability (84.9% capacity retention after 10,000 cycles at 1 A g-1 in PIBs and 74.0% capacity retention after 2200 cycles at 1 A g-1 in SIBs), and excellent rate capability (111 and 196 mAh g-1 at 5 A g-1 for PIBs and SIBs, respectively), which are superior to other MXene-based anodes for PIBs and SIBs. Moreover, the described strategy provides a new insight for constructing the 3D porous structure from 2D building blocks beyond MXene.

Nanoconfinement of ultra-small Bi2Te3 nanocrystals on reduced graphene oxide: a pathway to high-performance sodium-ion battery anodes.

Bismuth telluride (Bi2Te3) nanomaterials have attracted considerable attention owing to their intriguing physicochemical properties and wide-ranging potential applications arising from their distinctive layered structure and nanoscale size effects. However, synthesizing sub-100 nm ultra-small Bi2Te3 nanocrystals remains a formidable challenge. To date, there has been little investigation on the performance of these ultra-small Bi2Te3 nanocrystals in sodium-ion batteries (SIBs). This study presents a general strategy for synthesizing ultra-small Bi2Te3 nanocrystals on reduced graphene oxide (Bi2Te3/rGO) through a nanoconfinement approach. First-principles calculations and electrochemical kinetic studies confirm that the ultra-small Bi2Te3/rGO composite material can effectively mitigate volumetric expansion, preserve electrode integrity, and enhance electron transfer, Na-ion adsorption, and diffusion capacity. As a result, the Bi2Te3/rGO electrode demonstrates a remarkable initial specific capacity of 521 mA h g-1 at 0.1 A g-1, showcasing outstanding rate behaviour and long-lasting cycle life exceeding 800 cycles at 1 A g-1 while preserving exceptional rate properties. The function of the battery is indicated by ex situ TEM and XPS findings, which propose a conventional dual mechanism involving conversion and alloying. This work paves the way for rapid advancements in Bi2Te3-based SIB anodes while contributing to our understanding of sodium ion storage mechanisms.

Yolk-Shell MnSe/ZnSe Heterostructures with Selenium Vacancies Encapsulated in Carbontubes for High-Efficiency Sodium/Potassium Storage.

The pursuit of high-performance batteries has propelled the investigation into advanced materials and design methodologies. Herein, the yolk-shell MnSe/ZnSe heterojunction encapsulated in hollow carbontubes (MnSe/ZnSe@HCTs) is prepared as a prospective electrode material for sodium/potassium batteries. The band structure in the heterojunction is methodically adjusted and regulated by intentionally utilizing Mn with unpaired electrons in the 3d orbital. The ZnSe shell confer effectively mitigates volumetric expansion challenges inherent in ions insertion/extraction processes and 1D carbontubular conductive substrate avert the aggregation of MnSe/ZnSe nanoparticles. Concurrently, the heterojunctions implantation induces sublattice distortion and charge redistribution, enriching active sites and regulating band structure. The selenium vacancies within these heterojunctions contribute to the provision of abundant active sites, thereby promoting efficient ions insertion/extraction. In sodium-ion batteries (SIBs), MnSe/ZnSe@HCTs present a superior capacity of 475 mA hg-1 at 0.1 A g-1 and sustains a capacity of 408.5 mAh g-1 even after 1000 cycles. In potassium-ion batteries (KIBs), MnSe/ZnSe@HCTs deliver a higher specific capacity of 422 mAh g-1 at a current density of 0.1 A g-1 and maintain a high coulombic efficiency of 99% after 1000 cycles. The yolk-shell structured MnSe/ZnSe heterojunction demonstrates excellent electrode properties for high-performance sodium/potassium batteries, holding significant promise for future energy storage applications.

Dual carbon engineering enabling 1T/2H MoS2 with ultrastable potassium ion storage performance.

Potassium-ion batteries (PIBs) as a promising and low-cost battery technology offer the advantage of utilizing abundant and cost-effective K-salt sources. However, the effective adoption of PIBs necessitates the identification of suitable electrode materials. The 1T phase of MoS2 exhibits enhanced electronic conductivity and greater interlayer spacing compared to the 2H phase, leading to a capable potassium ion storage ability. Herein, we fabricated dual carbon engineered 1T/2H MoS2via a secure and straightforward ammonia-assisted hydrothermal method. The 1T/2H MoS2@rGO@C structure demonstrated an expanded interlayer spacing (9.3 Å). Additionally, the sandwich-like structural design not only enhanced material conductivity but also effectively curbed the agglomeration of nanosheets. Remarkably, 1T/2H MoS2@rGO@C exhibited impressive potassium storage ability, delivering capacities of 351.0 mA h g-1 at 100 mA g-1 and 233.8 mA h g-1 at 1000 mA g-1 following 100 and 1000 cycles, respectively. Moreover, the construction of a K-ion full cell was successfully achieved, utilizing perylene tetracarboxylic dianhydride (PTCDA) as the cathode, and manifesting a capacity of 294.3 mA h g-1 at 100 mA g-1 after 160 cycles. This underscores the substantial potential of employing the 1T/2H MoS2@rGO@C electrode material for PIBs.

Sulfur-Decorated Ti3 C2 TX MXene for High-Performance Sodium/Potassium-Ion Batteries.

As post-lithium ion batteries, both sodium-ion batteries (SIBs) and potassium ion batteries (PIBs) possess great potential for large scale energy storage. However, the application of both SIBs and PIBs are hindered by the lack of suitable electrode materials. Here, we synthesized the sulfur decorated Ti3 C2 Tx (S-T3 C2 Tx ) MXene as electrode material for SIBs and PIBs. Thanks to the sulfur functional group and the formation of Ti-S bond, which facilitates the sodium in-/desertion and strengthens the potassium ion adsorption ability, as well as enhances ion reaction kinetics and improved structure stability, the S-T3 C2 Tx exhibit excellent sodium/potassium storage performance, high reversible capacities of 151 and 101 mAh g-1 at 0.1 mA g-1 were achieved for SIBs and PIBs, respectively. Moreover, the S-T3 C2 Tx exhibits remarkable long-term capacity stability at a high density of 500 mA g-1 , providing an impressive storage of 88 mAh g-1 for SIBs and 41 mAh g-1 for PIBs even after 2000 cycles. This work could give a deep comprehension of the heteroatom modification influence on the MXene-based framework and promote the application of MXene electrodes.

High-Performance Alkali Metal Ion Storage in Bi2Se3 Enabled by Suppression of Polyselenide Shuttling Through Intrinsic Sb-Substitution Engineering.

Bismuth selenide holds great promise as a kind of conversion-alloying-type anode material for alkali metal ion storage because of its layered structure with large interlayer spacing and high theoretical specific capacity. Nonetheless, its commercial development has been significantly hammered by the poor kinetics, severe pulverization, and polyselenide shuttle during the charge/discharge process. Herein, Sb-substitution and carbon encapsulation strategies are simultaneously employed to synthesize SbxBi2-xSe3 nanoparticles decorated on Ti3C2Tx MXene with encapsulation of N-doped carbon (SbxBi2-xSe3/MX⊂NC) as anodes for alkali metal ion storage. The superb electrochemical performances could be assigned to the cationic displacement of Sb3+ that effectively inhibits the shuttling effect of soluble polyselenides and the confinement engineering that alleviates the volume change during the sodiation/desodiation process. When used as anodes for sodium- and lithium-ion batteries, the Sb0.4Bi1.6Se3/MX⊂NC composite exhibits superior electrochemical performances. This work offers valuable guidance to suppress the shuttling of polyselenides/polysulfides in high-performance alkali metal ion batteries with conversion/alloying-type transition metal sulfide/selenide anode materials.

Surface engineering of core-shell MoS2@N-doped carbon spheres as stable and ultra-long lifetime anode for sodium-ion batteries.

MoS2 is regarded as a hopeful anode candidate for sodium-ion batteries (SIBs) due to their various merits such as high specific capacity, abundant raw material reserves and low cost. However, their practical application is impeded by unsatisfied cycling ability due to the intense mechanical stress and unstable solid electrolyte interphase (SEI) during Na+ insertion/extraction process. Herein, spherical MoS2@polydopamine derived highly conductive N-doped carbon (NC) shell composites (MoS2@NC) are designed and synthesized to promote the cycling stability. The internal MoS2 core is optimized and restructured from the original micron-sized block to the ultra-fine nanosheets during initial 100-200 cycles, which not only improves the utilization of electrode materials but also shortens the ion transport distance. The outer flexible NC shell effectively maintains the original spherical structure of the overall electrode material and prevents the occurrence of large-scale agglomeration, which is conducive to form a stable SEI layer. Therefore, the core-shell MoS2@NC electrode presents a remarkable cyclic stability and a capable rate performance. Under a high rate of 20 A g-1, the high capacity of 428 mAh g-1 can be acquired after over ultra-long 10,000 cycles without obvious capacity loss. Moreover, the MoS2@NC‖Na3V2(PO4)3 full-cell assembled by employing commercial Na3V2(PO4)3 cathode can achieve a high capacity retention of 91.4% after 250 cycles at 0.4 A g-1. This work reveals the promising prospect of MoS2-based materials as anode of SIBs, and also has some inspirations on the structural design for conversion-type electrode materials.

A Potential Polycarbonyl Polyimide as Anode Material for Lithium-Ion Batteries.

Organic polymers have been considered reliable candidates for lithium storage due to their high capacity and lack of volume expansion. Compared with other organic polymers, polyimide has become a very promising electrode material for lithium-ion batteries (LIBs) because of its easy synthesis, customizable structure and structural stability. A large number of studies have confirmed that the benzene ring structure of polyimide has strong lithium storage capacity as an anode material. Hence, we designed and synthesized polyimide organic polymer (PBPAQ) for the first time. The unique spherical flower structure of this material enhances the interaction between the electrode material and the electrolyte by increasing the contact area. The PBPAQ anode has a specific discharge capacity of 738 mAh g-1 after 100 cycles at 0.1 A g-1 . The excellent lithium storage performance of this material laid a foundation for the research of the anode of LIBs in the future.

Exploring The Synergistic Effect Of CoSeP/CoP Interface Catalyst For Efficient Urea Electrolysis.

Electrocatalytic oxidation of urea (UOR) is a potential energy-saving hydrogen production technology that can replace oxygen evolution reaction (OER). Therefore, CoSeP/CoP interface catalyst is synthesized on nickel foam using hydrothermal, solvothermal, and in situ template methods. The strong interaction of tailored CoSeP/CoP interface promotes the hydrogen production performance of electrolytic urea. During the hydrogen evolution reaction (HER), the overpotential can reach 33.7 mV at 10 mA cm-2 . The cell voltage can reach 1.36 V at 10 mA cm-2 in the overall urea electrolytic process. Notably, the overall urine electrolysis performance of the catalyst in the human urine medium can reach 1.40 V at 10 mA cm-2 and can exhibit durable cycle stability at 100 mA cm-2 . Density functional theory (DFT) proves that the CoSeP/CoP interface catalyst can better adsorb and stabilize reaction intermediates CO* and NH* on its surface through a strong synergistic effect, thus enhancing the catalytic activity.

Boosting Magnesium Ion Storage Behavior via Heteroelement Doping in a Porous Tunnel Framework Cathode for Aqueous Mg-Ion Batteries.

To relieve the overwhelming pressure on fossil energy, aqueous magnesium ion batteries attracted tremendous attention owing to their low cost and high safety. However, the cathode materials are apt to occur lattice distortion because of the electrostatic interaction between magnesium ions and crystal. The 2×2 manganese octahedral molecular sieve with potassium ions and water located in the tunnels (K-OMS-2), utilized as a cathode material for chargeable magnesium ions batteries, is exposed to irreversible Mg2+ intercalation/deintercalation due to lattice distortion, which heavily damages the electrochemical properties and declines the capacity. Herein, we carry out an ion doping strategy to overcome the above issues, leading to an enhanced Mg Mg2+ storage behavior. The Nb or V cation is successfully doped into K-OMS-2 by a facile reflux method under room temperature. The specific surface area is enlarged by the addition of cations, which promise a large electrode-electrolyte contact area. The Nb and V doped K-OMS-2 present a capacity of 252.6 and 265.9 mAh/g at 20 mA/g, respectively. This work demonstrates an ion doping approach toward exploiting the stable and high-capacity Mg-ion battery cathode and provides potential cathode materials for a large-scale aqueous Mg-ion-based energy storage system.

A Novel Graphene Based Bi-Function Humidity Tolerant Binder for Lithium-Ion Battery.

Binders play a critical role in rechargeable lithium-ion batteries (LIBs) by holding granular electrode materials, conductive carbons, and current collectors firmly together to form and maintain a continuous electron conduction phase with sufficient mechanical strength. In the commercial LIBs, the dominant binder is polyvinylidene fluoride for the cathode (LiCoO2 , LiFePO4 , LiNix Coty Mnz O2 , etc.) and carboxyl methylcellulose/styrene-butadiene rubber for the anode (graphite and Li4 Ti5 O12 ). However, these polymer binders have several drawbacks, particularly, a lack of electronic and lithium-ion conductivities. Here, a novel organic/inorganic hybrid conductive binder (LAP-rGO) for both the anode and cathode of LIBs is reported. The binder consists of 2D reduced graphene oxide sheets with anchored long alkane chains. Electrodes prepared using this binder exhibit sufficient high bond strength, fast electrolyte diffusion, high rate charge/discharge performance, and excellent cycling stability. Around 130 mAh g-1 capacity enhancement at 5C is demonstrated for LiFePO4 and Li4 Ti5 O12 electrodes owing to the combined improvement in electron and lithium ion transportation. LAP-rGO bond graphite anode shows specific capacity beyond its theoretical value. Electrode slurries prepared using this new binder have superior processing and coating properties that can be prepared under a high humidity and dried using less energy.

Hierarchical CoNiO2 Microflowers Assembled by Mesoporous Nanosheets as Efficient Electrocatalysts for Hydrogen Evolution Reaction.

In order to alleviate the energy crisis and propel a low-carbon economy, hydrogen (H2) plays an important role as a renewable cleaning resource. To break the hydrogen evolution reaction (HER) bottleneck, we need high-efficiency electrocatalysts. Based on the synergistic effect between bimetallic oxides, hierarchical mesoporous CoNiO2 nanosheets can be fabricated. Combining physical representations with electrochemical measurements, the resultant CoNiO2 catalysts present the hierarchical microflowers morphology assembled by mesoporous nanosheets. The ultrathin two-dimensional nanosheets and porous surface characteristics provide the vast channels for electrolyte injection, thus endowing CoNiO2 the outstanding HER performance. The excellent performance with a fewer onset potential of 94 mV, a smaller overpotential at 10 mA cm-2, a lower Tafel slope of 109 mV dec-1 and better stability after 1000 cycles makes CoNiO2 better than that of metallic Co and metallic Ni.

Solvent Induced Activation Reaction of MoS2 Nanosheets within Nitrogen/Sulfur-Codoped Carbon Network Boosting Sodium Ion Storage.

MoS2 , as a classical 2D material, becomes a capable anode candidate for sodium-ion batteries. However, MoS2 presents a disparate electrochemical performance in the ether-based and ester-based electrolyte with unclear mechanism. Herein, tiny MoS2 nanosheets embedded in nitrogen/sulfur-codoped carbon (MoS2 @NSC) networks are designed and fabricated through an uncomplicated solvothermal method. Thanks to the ether-based electrolyte, the MoS2 @NSC shows a unique capacity growth in the original stage of cycling. But in the ester-based electrolyte, MoS2 @NSC shows a usual capacity decay. The increasing capacity puts down to the gradual transformation from MoS2 to MoS3 with the structure reconstruction. Based on the above mechanism, MoS2 @NSC demonstrates an excellent recyclability and the specific capacity keeps around 286 mAh g-1 at 5 A g-1 after 5000 cycles with an ultralow capacity fading rate of only 0.0034% per cycle. In addition, a MoS2 @NSC‖Na3 V2 (PO4 )3 full cell with ether-based electrolyte is assembled and demonstrates a capacity of 71 mAh g-1 , suggesting the potential application of MoS2 @NSC. Here the electrochemical conversion mechanism of MoS2 is revealed in the ether-based electrolyte and significance of the electrolyte design on the promoting Na ion storage behavior is highlighted.

A High-Rate and Long-Life Aqueous Rechargeable Mg-Ion Battery Based on an Organic Anode Integrating Diimide and Triazine.

Aqueous Mg-ion batteries (MIBs) lack reliable anode materials. This study concerns the design and synthesis of a new anode material - a π-conjugate of 3D-poly(3,4,9,10-perylenetracarboxylic diimide-1,3,5-triazine-2,4,6-triamine) [3D-P(PDI-T)] - for aqueous MIBs. The increased aromatic structure inhibits solubility in aqueous electrolytes, enhancing its structural stability. The 3D-P(PDI-T) anode exhibits several notable characteristics, including an extremely high rate capacity of 358 mAh g-1 at 0.05 A g-1 , A 3D-P(PDI-T)‖Mg2 MnO4 full cell exhibits a reversible capacity of 148 mAh g-1 and a long cycle life of 5000 cycles at 0.5 A g-1 . The charge storage mechanism reveals a synergistic interaction of Mg2+ and H+ cations with C-N/C=O groups. The assembled 3D-P(PDI-T)‖Mg2 MnO4 full cell exhibits a capacity retention of around 95 % after 5000 cycles at 0.5 A g-1 . This 3D-P(PDI-T) anode sustained its framework structure during the charge-discharge cycling of Mg-ion batteries. The reported results provide a strong basis for a cutting-edge molecular engineering technique to afford improved organic materials that facilitate efficient charge-storage behavior of aqueous Mg-ion batteries.

Three-dimensional Ti3C2Tx and MnS composites as anode materials for high performance alkalis (Li, Na, K) ion batteries.

Exploring capable and universal electrode materials could promote the development of alkalis (Li, Na, K) ion batteries. 2D MXene material is an ideal host for the alkalis (Li, Na, K) ion storage, but its electrochemical performance is limited by serious re-stacking and aggregation problems. Herein, we cleverly combined electrostatic self-assembly with gas-phase vulcanization method to successfully combine Ti3C2Tx-MXene with ultra-long recyclability and high conductivity with MnS, which presents high specific capacity but poor conductivity. The as-prepared 3D hierarchical Ti3C2Tx/MnS composites have an unique sandwich-like constituent units. The tiny MnS nanoparticles are restricted between the Ti3C2Tx layers and play a key role in expanding the Ti3C2Tx interlayer spacing. As a result, the 3D Ti3C2Tx/MnS composites as the anode of LIBs exhibits a superior capacities of 826 and 634 mAh/g after 1000 and 3000 cycles at 0.5 and 1.0 A/g, respectively. More importantly, we reveal the reaction mechanism that the specific capacity first increases and then gradually stabilizes with the increase of charge and discharge cycle times when the as-prepared 3D Ti3C2Tx/MnS was used as the anode of LIBs. In addition, we have also used this material in SIBs and PIBs and achieved remarkable electrochemical capability, with a specific capacity of 107 mAh/g after 2500 cycles at 0.5 A/g or 127 mAh/g after the 2000th cycle at 0.2 A/g, respectively.

Microwave-ultra-fast recovery of valuable metals from spent lithium-ion batteries by deep eutectic solvents.

The large-scale use of electric vehicles produced massive discarded lithium-ion batteries, containing many recyclable valuable metals and toxic and harmful substances. Biodegradable and recyclable deep eutectic solvent (DES) is considered a green recycling technology for spent LIBs. Herein, we proposed a microwave-enhanced approach to shorten the leaching time in the urea/lactic acid: choline chloride: ethylene glycol DES system. The dipole moments induced by urea or lactic acid on LiCoO2 surface increased over two orders of magnitude under the high electric field. Because of this, over 90 % of Li and Co can be fast leached at 4 min and 160 W in the urea/lactic acid: choline chloride: ethylene glycol DES system. Meanwhile, we established two models to explain the leaching mechanism of metal ions from their leaching kinetics and micro-level behavior, and named them dot-etching and layer-peeling processes, respectively. By further analyzing, we found that the dot-etching can be attributed to the synergistic effect of reduction and coordination, which caused the surface of leaching residues porous. The layer-peeling process depends on neutralization, and the leaching residues had a smooth surface in this process. This work highlights the effect of microwave-enhanced strategy and DES surface chemistry on spent electrode materials recovery.

Molybdenum sulfide selenide ultrathin nanosheets anchored on carbon tubes for rapid-charging sodium/potassium-ion batteries.

The structural stability and reaction kinetics of anodes are essential factors for high-performance battery systems. Herein, the molybdenum sulfide selenide (MoSSe) nanosheets anchored on carbon tubes (MoSSe@CTs) are synthesized by a facile hydrothermal method combining with further selenization/calcination treatment. The unique tubular carbon skeletons expose abundant active sites for the well-dispersed growth of MoS2 ultrathin nanosheets on both sides of the tubular carbon skeleton. In addition, the further selenization treatment can expand the interlayer spacing of molybdenum sulfide (MoS2) nanosheets and facilitate the fast sodium/potassium-ion transition and storage. When used in sodium-ion batteries (SIBs), MoSSe@CTs electrode delivers a specific capacity of 486 mAh g-1 at 1 A g-1 and retains a stable reversible capacity of 465 mAh g-1 after 1000 cycles, indicating its good cycling stability. For potassium-ion batteries (KIBs), the MoSSe@CTs composite shows a capacity of 352 mA hg-1 at 1 A g-1 and a good cycling stability (maintains at 272 mA hg-1 after 1000 cycles). This work shows informative guiding significance for exploring advanced electrode materials of sodium/potassium-ion batteries.

Li(110) lattice plane evolution induced by a 3D MXene skeleton for stable lithium metal anodes.

The non-uniform plating-stripping behaviours of Li metal anodes hinder the application of Li metal batteries. Here, a stable 3D matrix is designed by coating a carbon skeleton with MXene, and the significant influence of the crystallographic texture of Li metal on electrochemical behaviour is investigated. The results demonstrate that the 3D MXene/carbon skeleton can effectively induce the evolution of advantageous Li(110) facets with a dendrite-free anode interface. Consequently, the modified Li metal anodes deliver stable plating-stripping behaviours.