Reversible Oxygen-Rich Functional Groups Grafted 3D Honeycomb-Like Carbon Anode for Super-Long Potassium Ion Batteries

Extremely Durable K-Ion Batteries Enabled by Heteroatom Co-Doped Highly-Ordered Porous Carbon Spheres with Nearly 100% Capacity Retention up to 11,000 Cycles

Currently, one major target for exploring K-ion batteries (KIBs) is enhancing their cycle stability due to the intrinsically sluggish kinetics of large-radius K+ ions. Herein, we report a rationally designed electrode, the S/O co-doped hard carbon spheres with highly ordered porous characteristics (SPC), for extremely durable KIBs. Experimental results and theory calculations confirm that this structure offers exceptional advantages for high-performance KIBs, facilitating rapid K+ diffusion and (de)-intercalation, efficient electrolyte penetration and transport, improved K+ storage sites, and enhanced redox reaction kinetics, thus ensuring the long-term cycle stability. As a result, the as-constructed SPC anode delivers a high reversible capacity of ca. 200 mAh g-1 at a high current density of 2.0 A g-1 and robust stability with ∼100% capacity retention up to 11,000 cycles, outperforming most carbon-based KIB anodes. This work offers insight into developing advanced KIBs with durable stability toward practical applications.

Advances in Inorganic Foam Materials Fabricated Via Blowing Strategy: A Comprehensive Review

Two-dimensional (2D) materials with excellent properties and widespread applications have been explosively investigated. However, their conventional synthetic methods exhibit concerns of limited scalability, complex purification process, and incompetence of prohibiting their restacking. The blowing strategy, characterized by gas-template, low-cost, and high-efficiency, presents a valuable avenue for the synthesis of 2D-based foam materials and thereby addresses these constraints. Whereas, its comprehensive introduction has been rarely outlined so far. This review commences with a synopsis of the blowing strategy, elucidating its development history, the statics and kinetics of the blowing process, and the choice of precursor and foaming agents. Thereafter, we dwell at length on across-the-board foams enabled by the blowing route, like BxCyNz foams, carbon foams, and diverse composite foams consisting of carbon and metal compounds. Following that, a wide-ranging evaluation of the functionality of the foam products in fields such as energy storage, electrocatalysis, adsorption, etc. is discussed, revealing their distinctive strength originated from the foam structure. Finally, after concluding the current progress, we provide some personal discussions on the existing challenges and future research priorities in this rapidly developing method.

Structural Engineering of Hard-Soft Carbon Hybrid Anodes for Ultrafast and Ultradurable Potassium-Ion Storage

Hard-soft carbon hybrid materials, harvesting the expanded interlayer spacing of hard carbon and the high conductivity of soft carbon, hold great promise as anode materials for potassium-ion batteries, but efficient and precise structural control remains a major challenge. Herein, hollow porous bowl-like hard-soft carbon hybrid materials (BHSCs) are facilely synthesized by an in situ hard-template strategy. It is found that the outer and inner walls of the hard carbon bowls are uniformly wrapped by graphene-like soft carbon, which accelerates electron transport and promotes the insertion of potassium ions. Finite element simulation further reveals that the soft-hard-soft carbon shell structure releases stress during the insertion of potassium ions. As a result, BHSC anode exhibits an extraordinary rate capability (209 mAh g-1 at 10 A g-1) and excellent cycle stability with a capacity of 208 mAh g-1 after 5000 cycles at 2 A g-1. Impressively, the as-assembled potassium-ion hybrid capacitor based on BHSC anode delivers a great energy/power density (116 Wh kg-1/12980 W kg-1) and outstanding capacity retention of 83% after 8000 cycles. This work provides guidance for rational structural design of hard-soft carbon hybrid materials to improve their potassium-ion storage performance.

In Situ Chemical Modulation of Graphitization Degree of Carbon Fibers and Its Potassium Storage Mechanism

Graphite is considered to be the most auspicious anode candidate for potassium ion batteries. However, the inferior rate performances and cycling stability restrict its practical applications. Few studies have investigated the modulating the graphitization degree of graphitic materials. Herein, a nitrogen-doped carbon-coated carbon fiber composite with tunable graphitization (CNF@NC) through etching growth, in-situ oxidative polymerization, and subsequent carbonization process is reported. The prepared CNF@NC with abundant electrochemical active sites and a rapid K+/electron transfer pathway, can effectively shorten the K+ transfer distance and promote the rapid insertion/removal of K+. Amorphous domains and short-range curved graphite layers can provide ample mitigation spaces for K+ storage, alleviating the volume expansion of the highly graphitized CNF during repeated K+ insertion/de-intercalation. As expected, the CNF@NC-5 electrode presents a high initial coulombic efficiency (ICE) of 69.3%, an unprecedented reversible volumetric capacity of 510.2 mA h cm-3 at 0.1 A g-1 after 100 cycles with the mass-capacity of 294.9 mA h g-1. The K+ storage mechanism and reaction kinetic analysis are studied by combining in-situ analysis and first-principles calculation. It manifests that the K+ storage mechanism in CNF@NC-5 is an adsorption-insertion-insertion mechanism (i.e., the "1+2" model). The solid electrolyte interphase (SEI) film forming is also detected.

Halide-mediated endogenous ZnO domain-confined etching strategy: Realizing superior potassium storage in carbon anode

Coupling sites of nitrogen-dopants and intrinsic carbon defects (N/DC) are highly attractive to improve potassium-storage capacity and cycling stability, yet it is hard to effectively construct them. Herein, a novel strategy is proposed to establish abundant N/DC sites in N-doped carbon (ZIF8/NaBr-1-900) by pyrolyzing the mixture of metal-organic framework (ZIF8)/sodium bromide (NaBr). Systematic investigations disclose that the introduced NaBr can promote the full conversion of Zn-N4 moieties into zinc oxide (ZnO) via a "bait and switch" mechanism. Such formed endogenous ZnO can etch the carbon matrix of the confined domains around the N dopants during pyrolysis process, and meanwhile the released N-atoms from Zn-N4 moieties can largely form edge-N. As such, these N/DC coupling sites enable the resultant carbon to have a more significant capacitive behavior related to fast K-ion migration and high structural stability, leading to 255.3 mAh/g at 2 A/g with a prolonged cycle lifespan over 2000 cycles. Moreover, the assembled K-full battery presents a high energy density of 171.2 Wh kg-1 and excellent cyclability over 5000 cycles. This NaBr-mediated endogenous ZnO domain-confined etching strategy provides a new insight into the exploration of advanced carbon anode.

An oriented tube array porous carbon anode prepared using a self-blowing mold of salt templates for high-rate potassium storage

Porous carbon materials with oriented porosity are very useful in ion batteries, but their high cost and complex fabrication hinder their wide application. In this paper, we used cheap and water-soluble NaHCO3 grains to prepare unique porous carbon with an orderly arranged tube array via one-step carbonization. During the preparation process, a novel self-blowing mold of salt templates was discovered for the first time, and the resulting numerous high-speed gas jets can act as gas state templates to induce the formation of the oriented porous carbon into a mesoscale tube array with rich micropores. Besides, the amount of CO functional groups has been enhanced greatly by the chemical activation of H2O and CO2 derived from the decomposition of NaHCO3, which can improve the reversible specific capacity of the electrode by forming a C-O-K compound with potassium. Thanks to the coupling effect of the hierarchical porous structure with an orderly tube array and rich CO functional groups, the obtained porous carbon materials exhibited excellent kinetics and impressive rate capability as the anode of potassium-ion batteries (PIBs) with high capacities of 209 mA h g-1 at 10 A g-1 and 156 mA h g-1 at 30 A g-1. This work not only provides a facile, green, sustainable approach to fabricating novel carbon materials, but also demonstrates the promising prospect of oriented porous carbon in exploring advanced electrode materials for PIBs.

Insights into Nano- and Micro-Structured Scaffolds for Advanced Electrochemical Energy Storage

Adopting a nano- and micro-structuring approach to fully unleashing the genuine potential of electrode active material benefits in-depth understandings and research progress toward higher energy density electrochemical energy storage devices at all technology readiness levels. Due to various challenging issues, especially limited stability, nano- and micro-structured (NMS) electrodes undergo fast electrochemical performance degradation. The emerging NMS scaffold design is a pivotal aspect of many electrodes as it endows them with both robustness and electrochemical performance enhancement, even though it only occupies complementary and facilitating components for the main mechanism. However, extensive efforts are urgently needed toward optimizing the stereoscopic geometrical design of NMS scaffolds to minimize the volume ratio and maximize their functionality to fulfill the ever-increasing dependency and desire for energy power source supplies. This review will aim at highlighting these NMS scaffold design strategies, summarizing their corresponding strengths and challenges, and thereby outlining the potential solutions to resolve these challenges, design principles, and key perspectives for future research in this field. Therefore, this review will be one of the earliest reviews from this viewpoint.

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.

Dynamically Evolving Multifunctional Protective Layer for Highly Stable Potassium Metal Anodes

The construction of an artificial protective layer is an effective method to solve the issues, such as uncontrolled dendrite growth and an unstable solid electrolyte interphase, at the K metal anode. This study proposes a new dynamic evolution strategy that integrates the advantages of previous in situ and ex situ fabrication processes. A multifunctional protective layer enriched with K-Ge alloy is prepared on the K metal electrode by simple surface modification and in situ reduction via an electrochemical process. The protective layer has good potassiophilicity, mechanical flexibility, and high ionic conductivity, which can inhibit dendrite growth and reduce side reactions. The protected K electrode with a protective layer exhibits dendrite-free K plating/striping behavior, and the symmetric cell can run stably for over 1000 h at 1 mA cm-2 and 1 mAh cm-2. Notably, full cells based on this electrode also present excellent rate and cycling performance compared to those of the bare K electrode. This peculiar strategy will open a new avenue for metal anode protection and can be extended to other high-energy battery systems.

Carbon-based materials as efficient adsorbents for the removal of antibiotics: The real contributions of carbon edge sites

Disclosing the effect of edge defects in carbon-based materials on antibiotic removal remains a great challenge. In this study, carbon-based adsorbents (DC-s) with different degrees of edge defects were synthesized on a large scale via a direct calcination of sodium citrate (SC) and their adsorption performance to antibiotics were explored. The experimental results suggested that the edge defects of DC-s samples were the active sites for the adsorption of tetracycline (TC) and norfloxacin (NOR). The adsorption capacity of the optimal sample DC-900 for TC and NOR was 155.8 and 168.0 mg g-1, respectively. Density functional theory (DFT) calculations further revealed that zigzag edge defects rather than armchair edge defects were crucial to the excellent adsorption performance of DC-s samples for antibiotics, and the natures for the difference in the adsorption performance of the two edge defects for antibiotics were their different electronic structures. In addition, DC-900 also showed stable adsorption efficiency for antibiotics in the interferences, dynamic adsorption, and cycle experiments, suggesting its good environmental application potential. This study provides new insight into clarifying the natures of edge defects with carbon-based adsorbents for high-efficiency removal of antibiotics, which may guide the exploration of cost-effective carbon-based adsorbents.

Layered Potassium Titanium Niobate/Reduced Graphene Oxide Nanocomposite as a Potassium-Ion Battery Anode

With graphite currently leading as the most viable anode for potassium-ion batteries (KIBs), other materials have been left relatively under-examined. Transition metal oxides are among these, with many positive attributes such as synthetic maturity, long-term cycling stability and fast redox kinetics. Therefore, to address this research deficiency we report herein a layered potassium titanium niobate KTiNbO5 (KTNO) and its rGO nanocomposite (KTNO/rGO) synthesised via solvothermal methods as a high-performance anode for KIBs. Through effective distribution across the electrically conductive rGO, the electrochemical performance of the KTNO nanoparticles was enhanced. The potassium storage performance of the KTNO/rGO was demonstrated by its first charge capacity of 128.1 mAh g-1 and reversible capacity of 97.5 mAh g-1 after 500 cycles at 20 mA g-1, retaining 76.1% of the initial capacity, with an exceptional rate performance of 54.2 mAh g-1 at 1 A g-1. Furthermore, to investigate the attributes of KTNO in-situ XRD was performed, indicating a low-strain material. Ex-situ X-ray photoelectron spectra further investigated the mechanism of charge storage, with the titanium showing greater redox reversibility than the niobium. This work suggests this low-strain nature is a highly advantageous property and well worth regarding KTNO as a promising anode for future high-performance KIBs.

Built-In Electric Field-Driven Ultrahigh-Rate K-Ion Storage via Heterostructure Engineering of Dual Tellurides Integrated with Ti3C2Tx MXene

Exploiting high-rate anode materials with fast K+ diffusion is intriguing for the development of advanced potassium-ion batteries (KIBs) but remains unrealized. Here, heterostructure engineering is proposed to construct the dual transition metal tellurides (CoTe2/ZnTe), which are anchored onto two-dimensional (2D) Ti3C2Tx MXene nanosheets. Various theoretical modeling and experimental findings reveal that heterostructure engineering can regulate the electronic structures of CoTe2/ZnTe interfaces, improving K+ diffusion and adsorption. In addition, the different work functions between CoTe2/ZnTe induce a robust built-in electric field at the CoTe2/ZnTe interface, providing a strong driving force to facilitate charge transport. Moreover, the conductive and elastic Ti3C2Tx can effectively promote electrode conductivity and alleviate the volume change of CoTe2/ZnTe heterostructures upon cycling. Owing to these merits, the resulting CoTe2/ZnTe/Ti3C2Tx (CZT) exhibit excellent rate capability (137.0 mAh g-1 at 10 A g-1) and cycling stability (175.3 mAh g-1 after 4000 cycles at 3.0 A g-1, with a high capacity retention of 89.4%). More impressively, the CZT-based full cells demonstrate high energy density (220.2 Wh kg-1) and power density (837.2 W kg-1). This work provides a general and effective strategy by integrating heterostructure engineering and 2D material nanocompositing for designing advanced high-rate anode materials for next-generation KIBs.

Pseudocapacitive Potassium-Ion Intercalation Enabled by Topologically Defective Soft Carbon toward High-Rate, Large-Areal-Capacity, and Low-Temperature Potassium-Ion Batteries

Carbonaceous materials are widely investigated as anodes for potassium-ion batteries (PIBs). However, the inferior rate capability, low areal capacity, and limited working temperature caused by sluggish K-ions diffusion kinetics are still primary challenges for carbon-based anodes. Herein, a simple temperature-programmed co-pyrolysis strategy is proposed for the efficient synthesis of topologically defective soft carbon (TDSC) based on inexpensive pitch and melamine. The skeletons of TDSC are optimized with shortened graphite-like microcrystals, enlarged interlayer spacing, and abundant topological defects (e.g., pentagons, heptagons, and octagons), which endow TDSC with fast pseudocapacitive K-ion intercalation behavior. Meanwhile, micrometer-sized structure can reduce the electrolyte degradation over particle surface and avoid unnecessary voids, ensuring a high initial Coulombic efficiency as well as high energy density. These synergistic structural advantages contribute to excellent rate capability (116 mA h g-1 at 20 C), impressive areal capacity (1.83 mA h cm-2 with a mass loading of 8.32 mg cm-2 ), long-term cycling stability (capacity retention of 91.8% after 1200 h cycling), and low working temperature (-10 °C) of TDSC anodes, demonstrating great potential for the practical application of PIBs.

Trimming the Degrees of Freedom via a K+ Flux Rectifier for Safe and Long-Life Potassium-Ion Batteries

High degrees of freedom (DOF) for K+ movement in the electrolytes is desirable, because the resulting high ionic conductivity helps improve potassium-ion batteries, yet requiring support from highly free and flammable organic solvent molecules, seriously affecting battery safety. Here, we develop a K+ flux rectifier to trim K ion's DOF to 1 and improve electrochemical properties. Although the ionic conductivity is compromised in the K+ flux rectifier, the overall electrochemical performance of PIBs was improved. An oxidation stability improvement from 4.0 to 5.9 V was realized, and the formation of dendrites and the dissolution of organic cathodes were inhibited. Consequently, the K||K cells continuously cycled over 3,700 h; K||Cu cells operated stably over 800 cycles with the Coulombic efficiency exceeding 99%; and K||graphite cells exhibited high-capacity retention over 74.7% after 1,500 cycles. Moreover, the 3,4,9,10-perylenetetracarboxylic diimide organic cathodes operated for more than 2,100 cycles and reached year-scale-cycling time. We fabricated a 2.18 Ah pouch cell with no significant capacity fading observed after 100 cycles.

Densified graphene-like carbon nanosheets with enriched heteroatoms enabling superior gravimetric and volumetric potassium storage capacities

Constructing carbon electrodes with abundant heteroatoms and appropriate graphitic interlayer spacing remains a major challenge for achieving high gravimetric and volumetric potassium storage capacities with fast kinetics. Herein, we constructed 3D graphene-like N, F dual-doped carbon sheets induced by Ni template (N, F-CNS-Ni) with dense structure and rich active sites, providing a promising approach to address the facing obstacles. Highly reversible K-ion insertion/extraction is realized in the graphitic carbon structure, and K-adsorption capability is enhanced by introducing N/F heteroatoms. As a result, the N, F-CNS-Ni electrode exhibits ultrahigh gravimetric and volumetric capacities of 404.5 mA h g^-1 and 281.3 mA h cm^-3 at 0.05 A/g, respectively, and a superb capacity of 259.3 mA h g^-1 with a capacity retention ratio of 90 % even after 600 cycles at 5 A/g. This work presents a simple Ni-based template method to prepare graphene-like carbon nanosheets with high packing density and rich heteroatoms, and offers mechanism insight for achieving superior K-ion storage.

Unveiling the Nature of Ultrastable Potassium Storage in Bi0.48Sb1.52Se3 Composite

The conversion and alloying-type anodes for potassium-ion batteries (PIBs) have drawn attention. However, it is still a challenge to relieve the huge volume expansion/electrode pulverization. Herein, we synthesized a composite material comprising Bi_0.48Sb_1.52Se₃ nanoparticles uniformly dispersed in carbon nanofibers (Bi_0.48Sb_1.52Se₃@C). Benefiting from the synergistic effects of the high electronic conductivity of Bi_0.48Sb_1.52Se₃ and the mechanical confinement of the carbon fiber that buffers the large chemomechanical stress, the Bi_0.48Sb_1.52Se₃@C//K half cells deliver a high reversible capacity (491.4 mAh g^-1, 100 cycles at 100 mA g^-1) and an extraordinary cyclability (80% capacity retention, 1000 cycles at 1000 mA g^-1). Furthermore, the Bi_0.48Sb_1.52Se₃@C-based PIB full cells achieve a high energy density of 230 Wh kg^-1. In situ transmission electron microscopy (TEM) reveals an intercalation, conversion, and alloying three-step reaction mechanism and a reversible amorphous transient phase. More impressively, the nanofiber electrode can almost return to its original diameter after the potassiation and depotassiation reaction, indicating a highly reversible volume change process, which is distinct from the other conversion type electrodes. This work reveals the stable potassium storage mechanisms of Bi_0.48Sb_1.52Se₃@C composite material, which provides an effective strategy to enable conversion/alloying-type anodes for high performance PIBs for energy storage applications.

Confined Assembly of Hydrated Vanadium Oxide into Hollow Mesoporous Carbon Nanospheres for Fast and Stable K+ Storage Capability

The rational structural design of the electrode materials is significant to enhance the electrochemical performance for potassium ion storage, benefiting from the shortened ion diffusion distance, increased conductivity, and pseudo-capacitance promotion. Herein, hydrated vanadium oxide (HVO) nanosheets with enriched oxygen defects are well confined into hollow mesoporous carbon spheres (HMCS), producing O_d -VOH@C nanospheres through one-step hydrothermal reaction. Attributed to the restricted growth in the HMCS, the HVO nanosheets are loosely packed, generating abundant interfacial boundaries and large specific areas. As a result, O_d -VOH@C nanospheres show increased reaction kinetics and well buffer the volume effects for the K⁺ storage. O_d -VOH@C delivers stable capacities of 138 mAh g^-1 at 2.0 A g^-1 over 10 000 cycles in half-cells attributed to the high pseudo-capacitance contribution. The K⁺ storage mechanism of insertion and conversion reaction is confirmed by ex situ X-ray diffraction, Raman, and X-ray photoelectron spectroscopy analyses. Moreover, the symmetric potassium-ion capacitors of O_d -VOH@C//O_d -VOH@C deliver a high energy density of 139.6 Wh kg^-1 at the power density of 948.3 W kg^-1 .

Plastic-derived sandwich-like porous carbon nanosheet-supported hexagonal carbon micro-flakes for K-ion storage

Novel sandwich-like porous carbon nanosheet-supported hexagonal carbon micro-flakes (WPWMC) are fabricated via a one-step hydrothermal route at 700 °C with polyethylene as the precursor and magnesium as the inducer. Through various characterizations, it is confirmed that the hexagonal carbon micro-flakes exhibit (002) orientation, which exposes abundant edge active sites and shortens the K⁺ transmission path. Moreover, the inside cross-linked carbon nanosheets with abundant pores can accelerate ion diffusion and increase the capacitive contribution. The WPWMC anode displays a high reversible capacity (528.7 mA h g^-1 at 0.2 A g^-1), good rate capability (152.7 mA h g^-1 at 10 A g^-1) and long-term cycle stability (112.1 mA h g^-1 at 5 A g^-1 after 10 000 cycles). Furthermore, the WPWMC//CMK-3 hybrid capacitor exhibits an energy density of 222.7 W h kg^-1 at 446.2 W kg^-1. This work provides an idea for transforming waste plastic into value-added materials.

Self-Adaptive Re-Organization Enables Polythiophene as an Extraordinary Cathode Material for Aluminum-Ion Batteries with a Cycle Life of 100 000 Cycles

Aluminum-ion batteries (AIBs) have attracted great attentions in recent years. Organic materials such as polythiophene (PT) are promising cathode for AIBs. However, the capacity and cyclic stability of conventional organic cathode such as PT are limited by the inadequate degree of reaction and the unstable nature of organic materials. To obtain high-performance organic cathode, a new PT with the ability of self-adaptive re-organization was prepared. During cycling, its molecular chain can be re-organized, and the polymerization mode will change from C_α -C_α (α-PT) to C_β -C_β (β-PT). This change leads to smaller steric hindrance and faster kinetics during ion insertion which can lower the reaction energy barrier and stabilize the molecular structure. Benefited by this, AIBs with this cathode can deliver a specific capacity of 180 mAh g^-1 (@2 A g^-1 ) and a superb stability of 100 000 cycles at 10 A g^-1 . High energy density and power density can also be achieved with this cathode.

Ultrafast Synthesis of Metal-Layered Hydroxides in a Dozen Seconds for High-Performance Aqueous Zn (Micro-) Battery

Efficient synthesis of transition metal hydroxides on conductive substrate is essential for enhancing their merits in industrialization of energy storage field. However, most of the synthetic routes at present mainly rely on traditional bottom-up method, which involves tedious steps, time-consuming treatments, or additional alkaline media, and is unfavorable for high-efficiency production. Herein, we present a facile, ultrafast and general avenue to synthesize transition metal hydroxides on carbon substrate within 13 s by Joule-heating method. With high reaction kinetics caused by the instantaneous high temperature, seven kinds of transition metal-layered hydroxides (TM-LDHs) are formed on carbon cloth. Therein, the fastest synthesis rate reaches ~ 0.46 cm2 s-1. Density functional theory calculations further demonstrate the nucleation energy barriers and potential mechanism for the formation of metal-based hydroxides on carbon substrates. This efficient approach avoids the use of extra agents, multiple steps, and long production time and endows the LDHs@carbon cloth with outstanding flexibility and machinability, showing practical advantages in both common and micro-zinc ion-based energy storage devices. To prove its utility, as a cathode in rechargeable aqueous alkaline Zn (micro-) battery, the NiCo LDH@carbon cloth exhibits a high energy density, superior to most transition metal LDH materials reported so far.

Rationally Tailoring Superstructured Hexahedron Composed of Defective Graphitic Nanosheets and Macropores: Realizing Durable and Fast Potassium Storage

Multipores engineering composed of micro/mesopores is an effective strategy to improve potassium storage performance via providing enormous adsorption sites and shortened ions diffusion distance. However, a detailed exploration of the role played by macropores in potassium storage is still lacking and has been barely reported until now. Herein, a superstructure carbon hexahedron (DGN-900) is synthesized using poly tannic acid (PTA) as precursor. Due to the spatially confined two-step local contraction of PTA along different directions and dimensions during pyrolysis, defective nanosheets with macropores are formed, while realizing a balance between defects content and graphitization degree by regulating temperature. The presence of macropores is conducive to accelerating electrolyte ions rapid infiltration within electrode, and its pore volume can accommodate electrode structure fluctuation upon cycling, while the most suitable ratio of defects to graphitic provides rich ions adsorption sites and sufficient electrons transfer channels, simultaneously. These advantages enable a prominent electrochemical performance in DGN-900 electrode, including high rate (202.9 mAh g^-1 at 2 A g^-1 ) and long cycling stability over 2000 cycles. This unique fabrication strategy, that is, defects engineering coupled with macropores structure, makes fast and durable potassium storage possible.