Approaching the Downsizing Limit of Maricite NaFePO4 toward High‐Performance Cathode for Sodium‐Ion Batteries

Maricite NaFePO₄ nanodots with minimized sizes (≈1.6 nm) uniformly embedded in porous N‐doped carbon nanofibers (designated as NaFePO₄@C) are first prepared by electrospinning for maximized Na‐storage performance. The obtained flexible NaFePO₄@C fiber membrane adherent on aluminum foil is directly used as binder‐free cathode for sodium‐ion batteries, revealing that the ultrasmall nanosize effect as well as a high‐potential desodiation process can transform the generally perceived electrochemically inactive maricite NaFePO₄ into a highly active amorphous phase; meanwhile, remarkable electrochemical performance in terms of high reversible capacity (145 mA h g^?1 at 0.2 C), high rate capability (61 mA h g^?1 at 50 C), and unprecedentedly high cyclic stability (≈89% capacity retention over 6300 cycles) is achieved. Furthermore, the soft package Na‐ion full battery constructed by the NaFePO₄@C nanofibers cathode and the pure carbon nanofibers anode displays a promising energy density of 168.1 Wh kg^?1 and a notable capacity retention of 87% after 200 cycles. The distinctive 3D network structure of very fine NaFePO₄ nanoparticles homogeneously encapsulated in interconnected porous N‐doped carbon nanofibers, can effectively improve the active materials' utilization rate, facilitate the electrons/Na⁺ ions transport, and strengthen the electrode stability upon prolonged cycling, leading to the fascinating Na‐storage performance.     

All‐Cellulose‐Based Quasi‐Solid‐State Sodium‐Ion Hybrid Capacitors Enabled by Structural Hierarchy

Na‐ion hybrid capacitors consisting of battery‐type anodes and capacitor‐style cathodes are attracting increasing attention on account of the abundance of sodium‐based resources as well as the potential to bridge the gap between batteries (high energy) and supercapacitors (high power). Herein, hierarchically structured carbon materials inspired by multiscale building units of cellulose from nature are assembled with cellulose‐based gel electrolytes into Na‐ion capacitors. Nonporous hard carbon anodes are obtained through the direct thermal pyrolysis of cellulose nanocrystals. Nitrogen‐doped carbon cathodes with a coral‐like hierarchically porous architecture are prepared via hydrothermal carbonization and activation of cellulose microfibrils. The reversible charge capacity of the anode is 256.9 mAh g^?1 when operating at 0.1 A g^?1 from 0 to 1.5 V versus Na⁺/Na, and the discharge capacitance of cathodes tested within 1.5 to 4.2 V versus Na⁺/Na is 212.4 F g^?1 at 0.1 A g^?1. Utilizing Na⁺ and ClO₄^? as charge carriers, the energy density of the full Na‐ion capacitor with two asymmetric carbon electrodes can reach 181 Wh kg^?1 at 250 W kg^?1, which is one of the highest energy devices reported until now. Combined with macrocellulose‐based gel electrolytes, all‐cellulose‐based quasi‐solid‐state devices are demonstrated possessing additional advantages in terms of overall sustainability.     

Enhanced Ionic/Electronic Transport in Nano‐TiO2/Sheared CNT Composite Electrode for Na+ Insertion‐based Hybrid Ion‐Capacitors

Ion‐insertion capacitors show promise to bridge the gap between supercapacitors of high power densities and batteries of high energy densities. While research efforts have primarily focused on Li⁺‐based capacitors (LICs), Na⁺‐based capacitors (SICs) are theoretically cheaper and more sustainable. Owing to the larger size of Na⁺ compared to Li⁺, finding high‐rate anode materials for SICs has been challenging. Herein, an SIC anode architecture is reported consisting of TiO₂ nanoparticles anchored on a sheared‐carbon nanotubes backbone (TiO₂/SCNT). The SCNT architecture provides advantages over other carbon architectures commonly used, such as reduced graphene oxide and CNT. In a half‐cell, the TiO₂/SCNT electrode shows a capacity of 267 mAh g^?1 at a 1 C charge/discharge rate and a capacity of 136 mAh g^?1 at 10 C while maintaining 87% of initial capacity over 1000 cycles. When combined with activated carbon (AC) in a full cell, an energy density and power density of 54.9 Wh kg^?1 and 1410 W kg^?1, respectively, are achieved while retaining a 90% capacity retention over 5000 cycles. The favorable rate capability, energy and power density, and durability of the electrode is attributed to the enhanced electronic and Na⁺ conductivity of the TiO₂/SCNT architecture.     

Heterostructured Nanocube‐Shaped Binary Sulfide (SnCo)S2 Interlaced with S‐Doped Graphene as a High‐Performance Anode for Advanced Na+ Batteries

Heterostructuring electrodes with multiple electroactive and inactive supporting components to simultaneously satisfy electrochemical and structural requirements has recently been identified as a viable pathway to achieve high‐capacity and durable sodium‐ion batteries (SIBs). Here, a new design of heterostructured SIB anode is reported consisting of double metal‐sulfide (SnCo)S₂ nanocubes interlaced with 2D sulfur‐doped graphene (SG) nanosheets. The heterostructured (SnCo)S₂/SG nanocubes exhibit an excellent rate capability (469 mAh g^?1 at 10.0 A g^?1) and durability (5000 cycles, 487 mAh g^?1 at 5.0 A g^?1, 92.6% capacity retention). In situ X‐ray diffraction reveals that the (SnCo)S₂/SG anode undergoes a six‐stage Na⁺ storage mechanism of combined intercalation, conversion, and alloying reactions. The first‐principle density functional theory calculations suggest high concentration of p–n heterojunctions at SnS₂/CoS₂ interfaces responsible for the high rate performance, while in situ transmission electron microscopy unveils that the interlacing and elastic SG nanosheets play a key role in extending the cycle life.     

Ultrathin MoS2 Nanosheets@Metal Organic Framework‐Derived N‐Doped Carbon Nanowall Arrays as Sodium Ion Battery Anode with Superior Cycling Life and Rate Capability

This study reports the design and fabrication of ultrathin MoS₂ nanosheets@metal organic framework‐derived N‐doped carbon nanowall array hybrids on flexible carbon cloth (CC@CN@MoS₂) as a free‐standing anode for high‐performance sodium ion batteries. When evaluated as an anode for sodium ion battery, the as‐fabricated CC@CN@MoS₂ electrode exhibits a high capacity (653.9 mA h g^?1 of the second cycle and 619.2 mA h g^?1 after 100 cycles at 200 mA g^?1), excellent rate capability, and long cycling life stability (265 mA h g^?1 at 1 A g^?1 after 1000 cycles). The excellent electrochemical performance can be attributed to the unique 2D hybrid structures, in which the ultrathin MoS₂ nanosheets with expanded interlayers can provide shortened ion diffusion paths and favorable Na⁺ insertion/extraction space, and the porous N‐doped carbon nanowall arrays on flexible carbon cloth are able to improve the conductivity and maintain the structural integrity. Moreover, the N‐doping‐induced defects also make them favorable for the effective storage of sodium ions, which enables the enhanced capacity and rate performance of MoS₂.     

A New rGO‐Overcoated Sb2Se3 Nanorods Anode for Na+ Battery: In Situ X‐Ray Diffraction Study on a Live Sodiation/Desodiation Process

Sodium ion batteries (SIBs) are a promising alternative to lithium ion batteries for a broader range of energy storage applications in the future. However, the development of high‐performance anode materials is a bottleneck of SIBs advancement. In this work, Sb₂Se₃ nanorods uniformly wrapped by reduced graphene oxide (rGO) as a promising anode material for SIBs are reported. The results show that such Sb₂Se₃/rGO hybrid anode yields a high reversible mass‐specific energy capacity of 682, 448, and 386 mAh g^?1 at a rate of 0.1, 1.0, and 2.0 A g^?1, respectively, and sustains at least 500 stable cycles at a rate of 1.0 A g^?1 with an average mass‐specific energy capacity of 417 mAh g^?1 and capacity retention of 90.2%. In situ X‐ray diffraction study on a live SIB cell reveals that the observed high performance is a result of the combined Na⁺ intercalation, conversion reaction between Na⁺ and Se, and alloying reaction between Na⁺ and Sb. The presence of rGO also plays a key role in achieving high rate capacity and cycle stability by providing good electrical conductivity, tolerant accommodation to volume change, and strong electron interactions to the base Sb₂Se₃ anode.     

Bamboo‐Like Hollow Tubes with MoS2/N‐Doped‐C Interfaces Boost Potassium‐Ion Storage

Potassium‐ion batteries (KIBs) are new‐concept of low‐cost secondary batteries, but the sluggish kinetics and huge volume expansion during cycling, both rooted in the size of large K ions, lead to poor electrochemical behavior. Here, a bamboo‐like MoS₂/N‐doped‐C hollow tubes are presented with an expanded interlayer distance of 10 Å as a high‐capacity and stable anode material for KIBs. The bamboo‐like structure provides gaps along axial direction in addition to inner cylinder hollow space to mitigate the strains in both radial and vertical directions that ultimately leads to a high structural integrity for stable long‐term cycling. Apart from being a constituent of the interstratified structure the N‐doped‐C layers weave a cage to hold the potassiation products (polysulfide and the Mo nanoparticles) together, thereby effectively hindering the continuing growth of solid electrolyte interphase in the interior of particles. The density functional theory calculations prove that the MoS₂/N‐doped‐C atomic interface can provide an additional attraction toward potassium ion. As a result, it delivers a high capacity at a low current density (330 mAh g^?1 at 50 mA g^?1 after 50 cycles) and a high‐capacity retention at a high current density (151 mAh g^?1 at 500 mA g^?1 after 1000 cycles).     

A New Strategy to Build a High‐Performance P′2‐Type Cathode Material through Titanium Doping for Sodium‐Ion Batteries

Herein, Ti⁴⁺ in P′2‐Na_0.67[(Mn_0.78Fe_0.22)_0.9Ti_0.1]O₂ is proposed as a new strategy for optimization of Mn‐based cathode materials for sodium‐ion batteries, which enables a single phase reaction during de‐/sodiation. The approach is to utilize the stronger Ti–O bond in the transition metal layers that can suppress the movements of Mn–O and Fe–O by sharing the oxygen with Ti by the sequence of Mn–O–Ti–O–Fe. It delivers a discharge capacity of ≈180 mAh g^?1 over 200 cycles (86% retention), with S‐shaped smooth charge–discharge curves associated with a small volume change during cycling. The single phase reaction with a small volume change is further confirmed by operando synchrotron X‐ray diffraction. The low activation barrier energy of ≈541 meV for Na⁺ diffusion is predicted using first‐principles calculations. As a result, Na_0.67[(Mn_0.78Fe_0.22)_0.9Ti_0.1]O₂ can deliver a high reversible capacity of ≈153 mAh g^?1 even at 5C (1.3 A g^?1), which corresponds to ≈85% of the capacity at 0.1C (26 mA g^?1). The nature of the sodium storage mechanism governing the ultrahigh electrode performance in a full cell with a hard carbon anode is elucidated, revealing the excellent cyclability and good retention (≈80%) for 500 cycles (111 mAh g^?1) at 5C (1.3 A g^?1).     

Sodium Storage Behavior in Natural Graphite using Ether‐based Electrolyte Systems

This work reports that natural graphite is capable of Na insertion and extraction with a remarkable reversibility using ether‐based electrolytes. Natural graphite (the most well‐known anode material for Li–ion batteries) has been barely studied as a suitable anode for Na rechargeable batteries due to the lack of Na intercalation capability. Herein, graphite is not only capable of Na intercalation but also exhibits outstanding performance as an anode for Na ion batteries. The graphite anode delivers a reversible capacity of ≈150 mAh g^?1 with a cycle stability for 2500 cycles, and more than 75 mAh g^?1 at 10 A g^?1 despite its micrometer‐size (≈100 μm). An Na storage mechanism in graphite, where Na⁺‐solvent co‐intercalation occurs combined with partial pseudocapacitive behaviors, is revealed in detail. It is demonstrated that the electrolyte solvent species significantly affect the electrochemical properties, not only rate capability but also redox potential. The feasibility of graphite in a Na full cell is also confirmed in conjunction with the Na_1.5VPO_4.8F_0.7 cathode, delivering an energy of ≈120 Wh kg^?1 while maintaining ≈70% of the initial capacity after 250 cycles. This exceptional behavior of natural graphite promises new avenues for the development of cost‐effective and reliable Na ion batteries.     

Enhanced Reversible Sodium‐Ion Intercalation by Synergistic Coupling of Few‐Layered MoS2 and S‐Doped Graphene

Sodium‐ion batteries (SIBs) are regarded as the best alternative to lithium‐ion batteries due to their low cost and similar Na⁺ insertion chemistry. It is still challenging but greatly desired to design and develop novel electrode materials with high reversible capacity, long cycling life, and good rate capability toward high‐performance SIBs. This work demonstrates an innovative design strategy and a development of few‐layered molybdenum disulfide/sulfur‐doped graphene nanosheets (MoS₂/SG) composites as the SIB anode material providing a high specific capacity of 587 mA h g^?1 calculated based on the total composite mass and an extremely long cycling stability over 1000 cycles at a current density of 1.0 A g^?1 with a high capacity retention of ≈85%. Systematic characterizations reveal that the outstanding performance is mainly attributed to the unique and robust composite architecture where few‐layered MoS₂ and S‐doped graphene are intimately bridged at the hetero‐interface through a synergistic coupling effect via the covalently doped S atoms. The design strategy and mechanism understanding at the molecular level outlined here can be readily applied to other layered transition metal oxides for SIBs anode and play a key role in contributing to the development of high‐performance SIBs.     

Hierarchical NiS2 Modified with Bifunctional Carbon for Enhanced Potassium‐Ion Storage

Potassium‐ion batteries (PIBs) are currently drawing increased attention as a promising alternative to lithium‐ion batteries (LIBs) owing to the abundant resource and low cost of potassium. However, due to the large ionic radius size of K⁺, electrode material that can stably maintain K⁺ insertion/deintercalation is still extremely inadequate, especially for anode material with a satisfactory reversible capacity. As an attempt, nitrogen/carbon dual‐doped hierarchical NiS₂ is introduced as the electrode material in PIBs for the first time. Considering that the introduction of the carbon layer effectively alleviates the volume expansion of the material itself, further improves the electronic conductivity, and finally accelerates the charge transfer of K⁺, not surprisingly, NiS₂ decorated with the bifunctional carbon (NiS₂@C@C) material electrode shows excellent potassium storage performances. When utilized as a PIB anode, it delivers a high reversible capacity of 302.7 mAh g^?1 at 50 mA g^?1 after 100 cycles. The first coulombic efficiency is 78.6% and rate performance is 151.2 mAh g^?1 at 1.6 A g^?1 of the NiS₂@C@C, which are also notable. Given such remarkable electrochemical properties, this work is expected to provide more possibilities for the reasonable design of advanced electrode materials for metal sulfide potassium ion batteries.     

Bottom‐Up Synthesis of Advanced Carbonaceous Anode Materials Containing Sulfur for Na‐Ion Batteries

The fabrication of sulfur‐containing carbonaceous anode materials (CS) that show exceptional activity as anode material in Na‐ions batteries is reported. To do so, a general and straightforward bottom‐up synthesis of CS materials with precise control over the sulfur content and functionality is introduced. The new synthetic path combined with a detailed structural analysis and electrochemical studies provide correlations between i) the sulfur content and chemical species and ii) the structural, electronic, and electrochemical performance of the associated materials. As a result, the new CS substances demonstrate excellent activity as Na‐ion battery anode materials, reaching capacity values above 500 mAh g^?1 at a current density of 0.1 A g^?1, as well as high reversible sodium storage capabilities and excellent cycling durability. The results reveal the underlying working principles of carbonaceous materials, alongside the storage mechanism of the Na⁺ ions in these advanced sodium‐ion battery anode materials and provide a new avenue for their practical realization.     

Electrochemically Derived Graphene‐Like Carbon Film as a Superb Substrate for High‐Performance Aqueous Zn‐Ion Batteries

3D graphene, as a light substrate for active loadings, is essential to achieve high energy density for aqueous Zn‐ion batteries, yet traditional synthesis routes are inefficient with high energy consumption. Reported here is a simplified procedure to transform the raw graphite paper directly into the graphene‐like carbon film (GCF). The electrochemically derived GCF contains a 2D–3D hybrid network with interconnected graphene sheets, and offers a highly porous structure. To realize high energy density, the Na:MnO₂/GCF cathode and Zn/GCF anode are fabricated by electrochemical deposition. The GCF‐based Zn‐ion batteries deliver a high initial discharge capacity of 381.8 mA h g^?1 at 100 mA g^?1 and a reversible capacity of 188.0 mA h g^?1 after 1000 cycles at 1000 mA g^?1. Moreover, a recorded energy density of 511.9 Wh kg^?1 is obtained at a power density of 137 W kg^?1. The electrochemical kinetics measurement reveals the high capacitive contribution of the GCF and a co‐insertion/desertion mechanism of H⁺ and Zn²⁺ ions. First‐principles calculations are also carried out to investigate the effect of Na⁺ doping on the electrochemical performance of layered δ‐MnO₂ cathodes. The results demonstrate the attractive potential of the GCF substrate in the application of the rechargeable batteries.     

Hierarchical Engineering of Porous P2‐Na2/3Ni1/3Mn2/3O2 Nanofibers Assembled by Nanoparticles Enables Superior Sodium‐Ion Storage Cathodes

Layered transition metal oxides (TMOs) are appealing cathode candidates for sodium‐ion batteries (SIBs) by virtue of their facile 2D Na⁺ diffusion paths and high theoretical capacities but suffer from poor cycling stability. Herein, taking P2‐type Na_2/3Ni_1/3Mn_2/3O₂ as an example, it is demonstrated that the hierarchical engineering of porous nanofibers assembled by nanoparticles can effectively boost the reaction kinetics and stabilize the structure. The P2‐Na_2/3Ni_1/3Mn_2/3O₂ nanofibers exhibit exceptional rate capability (166.7 mA h g^?1 at 0.1 C with 73.4 mA h g^?1 at 20 C) and significantly improved cycle life (≈81% capacity retention after 500 cycles) as cathode materials for SIBs. The highly reversible structure evolution and Ni/Mn valence change during sodium insertion/extraction are verified by in operando X‐ray diffraction and ex situ X‐ray photoelectron spectroscopy, respectively. The facilitated electrode process kinetics are demonstrated by an additional study using the electrochemical measurements and density functional theory computations. More impressively, the prototype Na‐ion full battery built with a Na_2/3Ni_1/3Mn_2/3O₂ nanofibers cathode and hard carbon anode delivers a promising energy density of 212.5 Wh kg^?1. The concept of designing a fibrous framework composed of small nanograins offers a new and generally applicable strategy for enhancing the Na‐storage performance of layered TMO cathode materials.     

Reconstruction of Conformal Nanoscale MnO on Graphene as a High‐Capacity and Long‐Life Anode Material for Lithium Ion Batteries

To tackle the issue of inferior cycle stability and rate capability for MnO anode materials in lithium ion batteries, a facile strategy is explored to prepare a hybrid material consisting of MnO nanocrystals grown on conductive graphene nanosheets. The prepared MnO/graphene hybrid anode exhibits a reversible capacity as high as 2014.1 mAh g^?1 after 150 discharge/charge cycles at 200 mA g^?1, excellent rate capability (625.8 mAh g^?1 at 3000 mA g^?1), and superior cyclability (843.3 mAh g^?1 even after 400 discharge/charge cycles at 2000 mA g^?1 with only 0.01% capacity loss per cycle). The results suggest that the reconstruction of the MnO/graphene electrodes is intrinsic due to conversion reactions. A long‐term stable nanoarchitecture of graphene‐supported ultrafine manganese oxide nanoparticles is formed upon cycling, which yields a long‐life anode material for lithium ion batteries. The lithiation and delithiation behavior suggests that the further oxidation of Mn(II ) to Mn(IV ) and the interfacial lithium storage upon cycling contribute to the enhanced specific capacity. The excellent rate capability benefits from the presence of conductive graphene and a short transportation length for both lithium ions and electrons. Moreover, the as‐formed hybrid nanostructure of MnO on graphene may help achieve faster kinetics of conversion reactions.     

A General Metal‐Organic Framework (MOF)‐Derived Selenidation Strategy for In Situ Carbon‐Encapsulated Metal Selenides as High‐Rate Anodes for Na‐Ion Batteries

On account of increasing demand for energy storage devices, sodium‐ion batteries (SIBs) with abundant reserve, low cost, and similar electrochemical properties have the potential to partly replace the commercial lithium‐ion batteries. In this study, a facile metal‐organic framework (MOF)‐derived selenidation strategy to synthesize in situ carbon‐encapsulated selenides as superior anode for SIBs is rationally designed. These selenides with particular micro‐ and nanostructured features deliver ultrastable cycling performance at high charge–discharge rate and demonstrate ultraexcellent rate capability. For example, the uniform peapod‐like Fe₇Se₈@C nanorods represent a high specific capacity of 218 mAh g^?1 after 500 cycles at 3 A g^?1 and the porous NiSe@C spheres display a high specific capacity of 160 mAh g^?1 after 2000 cycles at 3 A g^?1. The current simple MOF‐derived method could be a promising strategy for boosting the development of new functional inorganic materials for energy storage, catalysis, and sensors.     

Constructing CoO/Co3S4 Heterostructures Embedded in N‐doped Carbon Frameworks for High‐Performance Sodium‐Ion Batteries

Heterostructures are attractive for advanced energy storage devices due to their rapid charge transfer kinetics, which is of benefit to the rate performance. The rational and facile construction of heterostructures with satisfactory electrochemical performance, however, is still a great challenge. Herein, ultrafine hetero‐CoO/Co₃S₄ nanoparticles embedded in N‐doped carbon frameworks (CoO/Co₃S₄@N‐C) are successfully obtained by employing metal‐organic frameworks as precursors. As anodes for sodium ion batteries, the CoO/Co₃S₄@N‐C electrodes exhibit high specific capacity (1029.5 mA h g^?1 at 100 mA g^?1) and excellent rate capability (428.0 mA h g^?1 at 5 A g^?1), which may be attributed to their enhanced electric conductivity, facilitated Na⁺ transport, and intrinsic structural stability. Density functional theoretical calculations further confirm that the constructed heterostructures induce electric fields and promote fast reaction kinetics in Na⁺ transport. This work provides a feasible approach to construct metal oxide/sulfide heterostructures toward high‐performance metal‐ion batteries.     

2D Nanospace Confined Synthesis of Pseudocapacitance‐Dominated MoS2‐in‐Ti3C2 Superstructure for Ultrafast and Stable Li/Na‐Ion Batteries

Exploring a universal strategy to implement the precise control of 2D nanomaterials in size and layer number is a big challenge for achieving ultrafast and stable Li/Na‐ion batteries. Herein, the confined synthesis of 1–3 layered MoS₂ nanocrystals into 2D Ti₃C₂ interlayer nanospace with the help of electrostatic attraction and subsequent cetyltrimethyl ammonium bromide (CTAB) directed growth is reported. The MoS₂ nanocrystals are tightly anchored into the interlayer by 2D confinement effect and strong Mo? C covalent bond. Impressively, the disappearance of Li⁺ intercalated into MoS₂ reduction peak is successfully observed for the first time in the experiment, showing in a typical surface‐controlled charge storage behavior. The pseudocapacitance‐dominated contribution guarantees a much faster and more stable Li/Na storage performance. As predicted, this electrode exhibits a very high Li⁺ storage capacity of 340 mAh g^?1 even at 20 A g^?1 and a long cycle life (>1000 times). It also shows an excellent Na⁺ storage capacity of 310 mAh g^?1 at 1 A g^?1 with a 1600 times high‐rate cycling. Such impressive confined synthesis strategy can be extended to the precise control of other 2D nanomaterials.     

An Ultrastable Nonaqueous Potassium‐Ion Hybrid Capacitor

Potassium‐ion hybrid capacitors (PIHCs) show great potential in large‐scale energy storage due to the advantages of electrochemical capacitors and potassium‐ion batteries. However, their development remains at the preliminary stage and is mainly limited by the kinetic imbalance between the two electrodes. Herein, an architecture of NbSe₂ nanosheets embedded in N, Se co‐doped carbon nanofibers (NbSe₂/NSeCNFs) as flexible, free‐standing, and binder‐free anodes for PIHCs is reported. The NbSe₂/NSeCNFs with hierarchically porous structure and N, Se co‐doping afford highly efficient channels for fast transportation of potassium ions and electrons during repeated cycling process. Furthermore, excellent electrochemical reversibility of the NbSe₂/NSeCNFs electrode is demonstrated through in situ XRD, in situ Raman, ex situ transmission electron microscopy and element mapping. Thus, PIHCs with the NbSe₂/NSeCNFs anode and active carbon cathode achieve a high energy of 145 W h kg^?1 at a current density of 50 mA g^?1, as well as an ultra‐long cycle life of over 10 000 cycles at a high current density of 2 A g^?1. These results indicate that the assembled PIHCs display great potential for applications in the field of ultra‐long cycling energy storage devices.     

Uniformly Confined Germanium Quantum Dots in 3D Ordered Porous Carbon Framework for High‐Performance Li‐ion Battery

Although abundant germanium (Ge)‐based anode materials have been explored to obtain high specific capacity, high rate performance, and long charge/discharge lifespans for lithium‐ion batteries (LIBs), their performances are still far from satisfactory due to the intrinsic defects of Ge and the relatively intricate anode structure. To work out these issues, a 3D ordered porous N‐doped carbon framework with Ge quantum dots uniformly embedded (3DOP Ge@N? C) as a binder‐free anode for LIBs via a facile polystyrene colloidal nanospheres template‐confined strategy is proposed. This unique structure not only facilitates Li‐ion diffusion and electron transport that can guarantee rapid de/alloying reaction, but also alleviates the huge volume changes during reactions and improves cycling stability. Notably, the resulting anode delivers a high specific reversible capacity (≈1160 mA h g^?1 at 1 A g^?1), superior rate properties (exceeding 500 mA h g^?1 at 40 A g^?1), and excellent cycling stability (over 90% capacity retention after 1200 cycles even at 5 A g^?1). Furthermore, both the 3DOP Ge@N? C anode with high areal mass loading (up to 8 mg cm^?2) and the full cell coupled with LiFePO₄ cathode display high capacity and cycling stability, further indicative of the favorable real‐life application prospects for high‐energy LIBs.