Electrical Conductivity Adjustment for Interface Capacitive-Like Storage in Sodium-Ion Battery

Sodium-ion battery (SIB) is significant for grid-scale energy storage. However, a large radius of Na ions raises the difficulties of ion intercalation, hindering the electrochemical performance during fast charge/discharge. Conventional strategies to promote rate performance focus on the optimization of ion diffusion. Improving interface capacitive-like storage by tuning the electrical conductivity of electrodes is also expected to combine the features of the high energy density of batteries and the high power density of capacitors. Inspired by this concept, an oxide-metal sandwich 3D-ordered macroporous architecture (3DOM) stands out as a superior anode candidate for high-rate SIBs. Taking Ni-TiO₂ sandwich 3DOM as a proof-of-concept, anatase TiO₂ delivers a reversible capacity of 233.3 mAh g⁻¹ in half-cells and 210.1 mAh g⁻¹ in full-cells after 100 cycles at 50 mA g⁻¹. At the high charge/discharge rate of 5000 mA g⁻¹, 104.4 mAh g⁻¹ in half-cells and 68 mAh g⁻¹ in full-cells can also be obtained with satisfying stability. In-depth analysis of electrochemical kinetics evidence that the dominated interface capacitive-like storage enables ultrafast uptaking and releasing of Na-ions. This understanding between electrical conductivity and rate performance of SIBs is expected to guild future design to realize effective energy storage.     

Single-Crystalline TiO2(B) Nanobelts with Unusual Large Exposed {100} Facets and Enhanced Li-Storage Capacity

The {100} facet of single-crystalline TiO₂(B) is an ideal platform for inserting Li ions, but it is hard to be obtained due to its high surface energy. Here, the single-crystalline TiO₂(B) nanobelts from H₂Ti₃O₇ with nearly 70% {100} facets exposed are synthesized, which significantly enhances Li-storage capacity. The first-principle calculations demonstrate an ab in-plane 2D diffusion through the exposed {100} facets. As a consequence, the nanobelts can significantly accommodate Li ions in LiTiO₂ formula with specific capacity up to 335 mAh g⁻¹, which is in good agreement with the electrochemical characterizations. Coating with conductive and protective poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate), the cut-off discharge voltage is as low as 0.5 V, leading to a capacity of 160.7 mAh g⁻¹ after 1500 cycles with a retention rate of 66% at 1C. This work provides a practical strategy to increase the Li-ion capacity and cycle stability by tailoring the crystal orientation and nanostructures.     

Vanadium Oxide Intercalated with Conductive Metal–Organic Frameworks with Dual Energy-Storage Mechanism for High Capacity and High-Rate Capability Zn Ion Storage

Vanadium oxides (VO_x) feature the potential for high-capacity Zn²⁺ storage, which are often preintercalated with inert ions or lattice water for accelerating Zn²⁺ migration kinetics. The inertness of these preintercalated species for Zn²⁺ storage and their incapability for conducting electrons, however, compromise the capacity and rate capability of VO_x. Herein, Ni-BTA, a 1D conductive metal–organic framework (c-MOF), is intercalated into the interlayer space of VO_x by coordinating organic ligands with preinserted Ni²⁺. The intercalated Ni-BTA improves the conductivity of VO_x by π–d conjugation, facilitates Zn²⁺ migration by enlarging its interlayer spacing, and stabilizes the crystal structure of VO_x as interlayer pillars, thus simultaneously enhancing the material's rate capability and cycling stability. Meanwhile, a dual reaction mechanism of Zn²⁺ storage, i.e., the redox of V⁵⁺/V³⁺ in VO_x and the rearrangement of chemical bonds (CN/C N) in Ni-BTA, collaboratively contributes to an enhanced capacity. Consequently, this Ni-BTA-intercalated VO_x material exhibits a high Zn²⁺ storage capacity of 464.2 mAh g⁻¹ at 0.2 A g⁻¹ and an excellent rate capability of 272.5 mAh g⁻¹ at 5 A g⁻¹. This work provides a general strategy for integrating c-MOFs with inorganic cathode materials to achieve high-capacity and high-rate performance.     

High-Performance All-Solid-State Batteries Enabled by Intimate Interfacial Contact Between the Cathode and Sulfide-Based Solid Electrolytes

All-solid-state batteries (ASSBs) are considered the ultimate next-generation rechargeable batteries due to their high safety and energy density. However, poor Li-ion kinetics caused by the inhomogeneous distribution of the solid electrolytes (SEs) and complex chemo-mechanical behaviors lead to poor electrochemical properties. In this study, LiNi_0.8Co_0.1Mn_0.1O₂ (NCM) (core) – Li₆PS₅Cl (LPSCl) SEs (shell) particles (NCM@LPSCl) are prepared by a facile mechano-fusion method to improve the electrochemical properties and increase the energy density of ASSBs. The conformally coated thin SEs layer on the surface of NCM enables homogeneous distribution of SEs in overall electrode and intimate physical contact with cathode material even under volume change of cathode material during cycling, which leads to the improvement in Li-ion kinetics without the increase in solid electrolyte content. As a result, an ASSBs employing NCM@LPSCl with 4 mAh cm⁻¹ specific areal capacity exhibits robust electrochemical properties, including the improved reversible capacity (163.1 mAh g⁻¹), cycle performance (90.0% after 100 cycles), and rate capability (discharge capacity of 152.69, 133.80, and 100.97 mAh g⁻¹ at 0.1, 0.2, and 0.5 C). Notably, ASSBs employing NCM@LPSCl composite show reliable electrochemical properties with a high weight fraction of NCM (87.3 wt%) in the cathode.     

A Soft Lithiophilic Graphene Aerogel for Stable Lithium Metal Anode

The lithium metal anode is one of the most promising anodes for next‐generation high‐energy‐density batteries. However, the severe growth of Li dendrites and large volume expansion leads to rapid capacity decay and shortened lifetime, especially in high current density and high capacity. Herein, a soft 3D Au nanoparticles@graphene hybrid aerogel (Au? GA) as a lithiophilic host for lithium metal anode is proposed. The large surface area and interconnected conductive pathways of the Au? GA significantly decrease the local current density of the electrode, enabling uniform Li deposition. Furthermore, the 3D porous structure effectively accommodates the large volume expansion during Li plating/stripping, and the Li_xAu alloy serves as a solid solution buffer layer to completely eliminate the Li nucleation over‐potential. Symmetric cells can stably cycle at 8 mA cm^?2 for 8 mAh cm^?2 and exhibit ultra‐long cycling: 1800 h at 2 mA cm^?2 for 2 mAh cm^?2, and 1200 h at 4 mA cm^?2 for 4 mAh cm^?2, with low over‐potential. Full cells assemble with a Cu@Au? GA? Li anode and LiFePO₄ cathode, can sustain a high rate of 8 C, and retain a high capacity of 59.6 mAh g^?1 after 1100 cycles at 2 C.     

Amorphous GaN@Cu Freestanding Electrode for High‐Performance Li‐Ion Batteries

GaN is demonstrated to be an ideal anode for Li‐ion batteries (LIBs) for the first time. Amorphous GaN@Cu nanorods (a‐GaN@Cu) freestanding electrode is designed via a low‐temperature pulsed laser deposition method, which exhibits prominent rate capability and untralong lifespan as an anode for LIBs. With porous interconnected metal nanorods substrate to improve the structure integrity and electronic conductivity, the a‐GaN@Cu electrode delivers a capacity recovery of 980 mAh g^?1 after 150 cycles from 0.25 to 6.25 A g^?1 and a high discharge capacity of 509 mAh g^?1 after 3000 cycles at 10.0 A g^?1. The lithium storage in the a‐GaN is also systematically studied, which suggests a redox reaction mechanism.     

Mechanism of Fast Storage of Li/Na in Complex Sb-Based Hybrid System

Antimony（Sb） has high theoretical specific capacity and moderate reaction potential, but poor cycling stability and rate performance caused by large volume expansion and sluggish reaction kinetics limit its development in alkali-ion batteries. The construction of carbon/Sb composites can solve this problem, but the traditional single carbon composite and poor Sb/carbon interface have limited promotion. Here, under the guidance of theoretical calculations, a strategy of hierarchical double carbon composite is proposed to enhance the performance of Sb anode, and systematically reveal the lithium/sodium ions (Li⁺/Na⁺) storage mechanism of Sb in complex composite system. Sb nanoparticles (Sb NPs) are encapsulated in carbon sphere matrix with strong interfacial chemical bond to form the first level composite material, and then the highly conductive and mechanically strong graphene is used as a three-dimensional skeleton network to connect the first level composite to form the second level composite material. The hierarchical double carbon/Sb composite exhibits excellent rate (228 mAh g⁻¹ @ 20 A g⁻¹) and long cycling performance (373.7 mAh g⁻¹ @ 2 A g⁻¹ after 2200 cycles, capacity retention of 93.1%). This work may expand structural design and interface regulation of Sb/C composites and providing theoretical guidance for metal anodes development.     

Oxygen Defects Engineering of VO2·xH2O Nanosheets via In Situ Polypyrrole Polymerization for Efficient Aqueous Zinc Ion Storage

What has been a crucial demand is that designing mighty cathode materials for aqueous zinc−ion batteries (AZIBs), which are vigorous alternative devices for large−scale energy storage by means of their high safety and low cost. Herein, a facile strategy is designed that combines oxygen defect engineering with polymer coating in a synergistic action. As an example, the oxygen−deficient hydrate vanadium dioxide with polypyrrole coating (O_d−HVO@PPy) is synthesized via a one-step hydrothermal method in which introducing oxygen vacancy in HVO is simultaneously realized during the in situ polymerization. Such a desirable material adjusts the surface adsorption and internal diffusion of Zn²⁺ demonstrated by electrochemical characterization and theoretical calculation results. Moreover, it also utilizes conductive polymer coating to improve electrical conductivity and suppress cathode dissolution. Therefore, the O_d−HVO@PPy electrode delivers a preferable reversible capacity (337 mAh g⁻¹ at 0.2 A g⁻¹) with an impressive energy density of 228 Wh kg⁻¹ and stable long cycle life. This enlightened design opens up a new modus operandi toward superior cathode materials for advanced AZIBs.     

Synergistic Effect between S and Se Enhancing the Electrochemical Behavior of SexSy in Aqueous Zn Metal Batteries

Developing high-capacity conversional cathode materials for aqueous Zn batteries is promising to improve their energy densities but challenging as well. In this work, three kinds of selenium–sulfur solid solutions and their composites (denoted as SeS₁₄ @ 3D-NPCF, SeS_5.76 @ 3D-NPCF, and SeS_2.46 @ 3D-NPCF) are proposed and systematically investigated. Due to the introduction of Se and its synergistic effect with S, their physical and electrochemical properties are manipulated; in particular, by optimizing the Se content in these composites, SeS_5.76 @ 3D-NPCF shows a capacity of 1222 mAh g⁻¹ and flat plateau of 0.71 V at 0.2 A g⁻¹, reaching an ultrahigh energy density of 867.6 Wh kg⁻¹ (based on SeS_5.76), superior rate capacity of 713 mAh g⁻¹ at 5 A g⁻¹, and stable cycling of 75% capacity retention after 500 cycles. In addition, the Zn storage kinetics is determined by the discharge process, during which SeS_5.76 @ 3D-NPCF is converted into ZnSe and ZnS. More importantly, theoretical calculations reveal that Se can tailor the electron density difference, band structure, and reaction energy of S, which increase its conductivity and reactivity to facilitate the electrochemical reaction with Zn. This work explores high performance conversional cathode materials for aqueous Zn metal batteries and presents an effective strategy to modify their intrinsic properties.     

Exceptional Lithium-Ion Storage Performance on an Azo-Bridged Covalent Heptazine Framework

Graphitic carbon nitride (g-C₃N₄) possesses rich pyridine nitrogens, which is helpful for facilitating electrochemical capability in Li⁺ storage; however, its poor conductivity is still the main challenge. Based on the knowledge of its intrinsic merits and defects, here, it is proposed to integrate active heptazine (HEP) species with functional linkers into orderly molecular structures for improved performance. As the first proof-of-concept, a unique azo-linked covalent heptazine framework (Azo-CHF) where two HEP units are bridged with azo linkages, is ingeniously designed and prepared to enhance the inherent charge conductivity for Li⁺ storage. Attributing to the deeply extended conjugation along overlapping azo nitrogens and the aromatic π system of HEP cores, Azo-CHF with the lowest bandgap (2.58 eV) exhibits enhanced Li⁺/e⁻ transport than g-C₃N₄ through density functional theory calculations. Therefore, the Azo-CHF anode exhibits an unprecedented performance with a large reversible capacity (1723.0 mAh g⁻¹ at 0.1 A g⁻¹), superior rate capability (824.0 mAh g⁻¹ at 10 A g⁻¹), and impressive cyclability (756.5 mAh g⁻¹ undergoing 1000 cycles at 10 A g⁻¹). This study not only demonstrates the great application prospect of Azo-CHF for Li⁺ storage, but also opens a fantastic window to further explore high-performance electrodes by integrating HEP with other active motifs.     

Interconnected Metallic Membrane Enabled by MXene Inks Toward High-Rate Anode and High-Voltage Cathode for Li-Ion Batteries

The ever-increasing popularity of smart electronics demands advanced Li-ion batteries capable of charging faster and storing more energy, which in turn stimulates the innovation of electrode additives. Developing single-phase conductive networks featuring excellent mechanical strength/integrity coupled with efficient electron transport and durability at high-voltage operation should maximize the rate capability and energy density, however, this has proven to be quite challenging. Herein, it is shown that a 2D titanium carbide (known as MXene) metallic membrane can be used as single-phase interconnected conductive binder for commercial Li-ion battery anode (i.e., Li₄Ti₅O₁₂) and high-voltage cathodes (i.e., Ni_0.8Mn_0.1Co_0.1O₂). Electrodes are fabricated directly by slurry-casting of MXene aqueous inks composited with active materials without any other additives or solvents. The interconnected metallic MXene membrane ensures fast charge transport and provides good durability, demonstrating excellent rate performance in the Li//Li₄Ti₅O₁₂ cell (90 mAh g⁻¹ at 45 C) and high reversible capacity (154 mAh g⁻¹ at 0.2 C/0.5 C) in Li//Ni_0.8Mn_0.1Co_0.1O₂ cell coupled with high-voltage operation (4.3 V vs Li/Li⁺). The LTO//NMC full cell demonstrates promising cycling stability, maintaining capacity retention of 101.4% after 200 cycles at 4.25 V (vs Li/Li⁺) operation. This work provides insights into the rational design of binder-free electrodes toward acceptable cyclability and high-power density Li-ion batteries.     

A Shape-Variable,Low-Temperature Liquid Metal–Conductive Polymer Aqueous Secondary Battery

A shape-variable aqueous secondary battery operating at low temperature is developed using Ga₆₈In₂₂Sn₁₀ (wt%) as a liquid metal anode and a conductive polymer (polyaniline (PANI)) cathode. In the GaInSn alloy anode, Ga is the active component, while Sn and In increase the acid resistance and decrease the eutectic point to -19 °C. This enables the use of strongly acidic aqueous electrolytes (here, pH 0.9), thereby improving the activity and stability of the PANI cathode. Consequently, the battery exhibits excellent electrochemical performance and mechanical stability. The GaInSn–PANI battery operates via a hybrid mechanism of Ga³⁺ stripping/plating and Cl⁻ insertion/extraction and delivers a high reversible capacity of over 223.9 mAh g⁻¹ and an 80.3% retention rate at 0.2 A g⁻¹ after 500 cycles, as well as outstanding power and energy densities of 4300 mW g⁻¹ and 98.7 mWh g⁻¹, respectively. Because of the liquid anode, the battery without packaging can be deformed with a small force of several millinewtons without any capacity loss. Moreover, at approximately -5 °C, the battery delivers a capacity of 67.8 mAh g⁻¹ at 0.2 A g⁻¹ with 100% elasticity. Thus, the battery is promising as a deformable energy device at low temperatures and in demanding environments.     

Bi Dots Confined by Functional Carbon as High-Performance Anode for Lithium Ion Batteries

Fabrication of Bi/C composites is a common approach to alleviate the severe volume expansion of Bi alloy-based anodes with a high theoretical capacity of 3800 mAh cm⁻³ for lithium ion batteries (LIBs). However, the complicated and tedious synthetic routes restrict its large-scale preparation and practical applications. Herein, a spongiform porous Bi/C composite (marked as Bi@PC) through the carbothermal reduction (CTR) method is constructed. Bi nanodots are in situ confined in a porous carbon substrate activated by the gases produced from the decomposition of the sodium phytate precursor, indicating the feasibility and simplicity of this route. In charge/discharge processes, Bi nanodots embedded in carbon matrix are effective enough to accommodate the strain change and shorten the migration distance. In addition, the porous carbon forms an efficient conductive network for electron shutting. When utilized for lithium storage, a superb capacity of 520 mAh g⁻¹ at 0.2 A g⁻¹ after 100 cycles and a satisfying long cyclic stability of 380 mAh g⁻¹ at 0.5 A g⁻¹ after 500 cycles are achieved. The excellent Li-storage performance and this handy preparation method jointly make this Bi/C composite a potential anode for LIBs, and could inspire the preparation of other alloy-type anodes.     

3D Carbon Nanotube Network Bridged Hetero‐Structured Ni‐Fe‐S Nanocubes toward High‐Performance Lithium,Sodium, and Potassium Storage

Lithium‐ion, sodium‐ion, and potassium‐ion batteries have captured tremendous attention in power supplies for various electric vehicles and portable electronic devices. However, their practical applications are severely limited by factors such as poor rate capability, fast capacity decay, sluggish charge storage dynamics, and low reversibility. Herein, hetero‐structured bimetallic sulfide (NiS/FeS) encapsulated in N‐doped porous carbon cubes interconnected with CNTs (Ni‐Fe‐S‐CNT) are prepared through a convenient co‐precipitation and post‐heat treatment sulfurization technique of the corresponding Prussian‐blue analogue nanocage precursor. This special 3D hierarchical structure can offer a stable interconnect and conductive network and shorten the diffusion path of ions, thereby greatly enhancing the mobility efficiency of alkali (Li, Na, K) ions in electrode materials. The Ni‐Fe‐S‐CNT nanocomposite maintains a charge capacity of 1535 mAh g^?1 at 0.2 A g^?1 for lithium ion batteries, 431 mAh g^?1 at 0.1 A g^?1 for sodium ion batteries, and 181 mAh g^?1 at 0.1 A g^?1 for potassium‐ion batteries, respectively. The high performance is mainly attributed to the 3D hierarchically high‐conductivity network architecture, in which the hetero‐structured FeS/NiS nanocubes provide fast Li⁺/Na⁺/K⁺ insertion/extraction and reduced ion diffusion paths, and the distinctive 3D networks maintain the electrical contact and guarantee the structural integrity.     

Boosting Potassium Storage Kinetics,Stability, and Volumetric Performance of Honeycomb-Like Porous Red Phosphorus via In Situ Embedding Self-Growing Conductive Nano-Metal Networks

Large volume expansion and sluggish reaction kinetics of low-conductivity red phosphorus (RP) anodes hinder its practical application in potassium-ion batteries (PIBs). Here, a self-limited growth strategy to fabricate Bi (Sb) nanoparticles is demonstrated, as electrochemically active and conductive coating, in situ embedded into honeycomb-like porous red phosphorus (HPRP) to form HPRP@Bi (HPRP@Sb) composites, greatly improving the potassium-storage kinetics, stability and volumetric performance of HPRP. Here, Bi nanoparticles are converted into amorphous Bi during cycling, which are uniformly coated on the porous HPRP skeleton to form 3D conductive Bi networks. Theoretical calculations verify that introducing amorphous Bi significantly decreases K⁺ diffusion barrier in composites, and greatly enhancing their electrical conductivity and interfacial ion transport between HPRP and Bi, thereby accelerating their potassium storage kinetics and stability. Whereas the robust porous structure and inward expansion mechanism of HPRP effectively buffer their volume expansion of RP and Bi. Therefore, HPRP@Bi anode delivers high gravimetric and volumetric capacity (465.6 mAh g⁻¹, 745 mAh cm⁻³) and stable long lifespan with 200 cycles at 0.05 A g⁻¹ in PIBs. This work demonstrates a new approach to promote ion storage kinetics and stability of RP via integrating the synergy of high-conductivity active metal and high-capacity porous RP.     

FeP Quantum Dots Confined in Carbon‐Nanotube‐Grafted P‐Doped Carbon Octahedra for High‐Rate Sodium Storage and Full‐Cell Applications

Transition metal phosphides (TMPs) possess high theoretical sodium storage capacities, but suffer from poor rate performance, due to their intrinsic low conductivity and large volume expansion upon sodiation/desodiation. Compositing TMPs with carbon materials or downsizing their feature size are recognized as efficient approaches to address the above issues. Nevertheless the surface‐controlled capacitive behavior is generally dominated, which inevitably compromises the charge/discharge platform, and decreases the operational potential window in full‐cell constructions. In this work, a novel architecture (FeP@OCF) with FeP quantum dots confined in P‐doped 3D octahedral carbon framework/carbon nanotube is rationally designed. Such structure enables a simultaneous enhancement on the diffusion‐controlled capacity in the platform region (2.3 folds), and the surface‐controlled capacity in the slope region (2.9 folds) as compared to that of pure FeP. As a result, an excellent reversible capacity (674 mAh g^?1@ 0.1 A g^?1) and a record high‐rate performance (262 mAh g^?1 @ 20 A g^?1) are achieved. A full‐cell FeP@OCF// Na₃V₂(PO₄)₃ is also constructed showing an outstandingly high energy density of 185 Wh kg^?1 (based on the total mass of active materials in both electrodes), which outperforms the state‐of‐the art TMP‐based sodium‐ion battery full cells.     

Magnesium-Ion Battery Anode from Polymer-Derived SiOC Nanobeads

Tin-containing silicon oxycarbide (SiOC/Sn) nanobeads are synthesized with different carbon/tin content and tested as electrodes for magnesium-ion batteries. The synthesized ceramics are characterized by thermogravimetric-mass spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction (XRD), Raman spectroscopy, N₂ sorption analysis, scanning electron microscope, energy-dispersive X-ray, and elemental analysis. Galvanostatic cycling tests, rate performance tests, electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) tests, and ex situ XRD measurements are conducted. Results of battery performance tests present a high capacity of 198.2 mAh g⁻¹ after the first discharging and a reversible capacity of 144.5 mAh g⁻¹ after 100 cycles at 500 mA g⁻¹. Excellent rate performance efficiency of 85.2% is achieved. Battery performances in this research are influenced by surface area, and tin contentof the SiOC/Sn nanobeads. EIS, CV tests, and ex situ XRD measurements reveal that higher surface area contributes to higher capacity by providing more accessible Mg²⁺ ion storage sites and higher rate capability by improving the diffusion process. Higher Sn content increases battery capacity through reversible Mg-Mg₂Sn-Mg alloying/dealloying process and improves the rate performances by increasing electrical conductivity. Besides, SiOC advances cycling stability by preventing electrode collapse and enhances the capacity due to higher surface capacitive effects.     

Universal Source-Template Route to Metal Selenides Implanting on 3D Carbon Nanoarchitecture: Cu2−xSe@3D-CN with Se?C Bonding for Advanced Na Storage

The development of high-performance sodium ion batteries (SIBs) is heavily relied on the exploration of the appropriate electrode material for Na⁺ storage, which ought to feature merits of high capacity, easy-to-handle synthesis, high conductivity, expedite mass transportation, and stable structure upon charging–discharging cycle. Herein, a universal source-template method is reported to synthesize a variety of transition metal (e.g., V, Sb, W, Zn, Fe, Co, Ni, and Cu) selenides implanting on N doped 3D carbon nanoarchitecture hybrids (M_mSe_n@3D-CN) with powerful Se C bonding rivet. Benefiting from the superior architecture and potent Se C bonding between Cu_2−xSe and N-doped 3D carbon (3D-CN), the Cu_2−xSe@3D-CN nanohybrids, as anode of SIBs, show high capacity, high-rate capability, and long-cycle durability, which can deliver a reversible capacity of as high as 386 mAh g⁻¹, retain 219 mAh g⁻¹ even at 10 A g⁻¹, and run durably over thousands of charging–discharging cycles. The Cu_2−xSe@3D-CN as anode is also evaluated by developing a full SIB by coupling with the Na₃V₂(PO₄)₃ cathode, which can deliver high energy density and show excellent stability, shedding light on its potential in practical application.     

Highly Connected Silicon–Copper Alloy Mixture Nanotubes as High‐Rate and Durable Anode Materials for Lithium‐Ion Batteries

Seeking high‐capacity, high‐rate, and durable anode materials for lithium‐ion batteries (LIBs) has been a crucial aspect to promote the use of electric vehicles and other portable electronics. Here, a novel alloy‐forming approach to convert amorphous Si (a‐Si)‐coated copper oxide (CuO) core–shell nanowires (NWs) into hollow and highly interconnected Si–Cu alloy (mixture) nanotubes is reported. Upon a simple H₂ annealing, the CuO cores are reduced and diffused out to alloy with the a‐Si shell, producing highly interconnected hollow Si–Cu alloy nanotubes, which can serve as high‐capacity and self‐conductive anode structures with robust mechanical support. A high specific capacity of 1010 mAh g^?1 (or 780 mAh g^?1) has been achieved after 1000 cycles at 3.4 A g^?1 (or 20 A g^?1), with a capacity retention rate of ≈84% (≈88%), without the use of any binder or conductive agent. Remarkably, they can survive an extremely fast charging rate at 70 A g^?1 for 35 runs (corresponding to one full cycle in 30 s) and recover 88% capacity. This novel alloy‐nanotube structure could represent an ideal candidate to fulfill the true potential of Si‐loaded LIB applications.     

3D Printed Nanocarbon Frameworks for Li-Ion Battery Cathodes

The use of conductive carbon materials in 3D-printing is attracting growing academic and industrial attention in electrochemical energy storage due to the high customization and on-demand capabilities of the additive manufacturing. However, typical polymers used in conductive filaments for 3D printing show high resistivity and low compatibility with electrochemical energy applications. Removal of insulating thermoplastics in as-printed materials is a common post-printing strategy, however, excessive loss of thermoplastics can weaken the structural integrity. This work reports a two-step surface engineering methodology for fabrication of 3D-printed carbon materials for electrochemical applications, incorporating conductive poly(ortho-phenylenediamine) (PoPD) via electrodeposition. A conductive PoPD effectively enhances the electrochemical activities of 3D-printed frameworks. When PoPD-refilled frameworks casted with LiMn₂O₄ (LMO) composite materials used as battery cathode, it delivers a capacity of 69.1 mAh g⁻¹ at a current density of 0.036 mA cm⁻² ( ≈ 1.2 C discharge rate) and good cyclability with a retained capacity of 84.4% after 200 cycles at 0.36 mA cm⁻². This work provides a pathway for developing electroactive 3D-printed electrodes particularly with cost-efficient low-dimensional carbon materials for aqueous rechargeable Li-ion batteries.