High‐Performance Three‐Dimensional Li Anode Scaffold Enabled by Homogeneous Zn Nanoclusters

The large‐scale implementation of lithium metal batteries (LMBs) has long been plagued by the uncontrollable Li deposition triggered safety issues. Herein, a lithiophilic three‐dimensional Li anode scaffold, which is prepared by molten Li infusion aided by confined growth of low‐cost Zn clusters, is rationally constructed for high‐performance LMBs. Owing to the synergy of the carbon host and the effective regulation from the Zn nanoclusters, the large volumetric change of Li metal is well mitigated and shows a smooth and dendrite‐free behavior. The Li anode scaffold can deliver much improved Coulombic efficiency, superior rate performance, and long cycle lifespan with much lower voltage polarization. Furthermore, the half cells of Li anode scaffold paired with LiFePO₄/LiCoO₂/sulfur can achieve a higher specific capacity and longer stable cycling life than those with conventional Li foil. The Li|LFP cells can achieve a stable cycling over 250 cycles at 1C with a higher capacity retention of ≈90.8%, and a higher initial discharge capacity of 924.6 mAh g^?1 with a high capacity retention over 300 cycles can also be obtained in Li|S cells at 1C. This work demonstrates a cost‐effective and scalable strategy for stable Li metal anode toward next‐generation and high‐performance LMBs.     

Interlayered Dendrite‐Free Lithium Plating for High‐Performance Lithium‐Metal Batteries

For its high theoretical capacity and low redox potential, Li metal is considered to be one of the most promising anode materials for next‐generation batteries. However, practical application of a Li‐metal anode is impeded by Li dendrites, which are generated during the cycling of Li plating/stripping, leading to safety issues. Researchers attempt to solve this problem by spatially confining the Li plating. Yet, the effective directing of Li deposition into the confined space is challenging. Here, an interlayer is constructed between a graphitic carbon nitrite layer (g‐C₃N₄) and carbon cloth (CC), enabling site‐directed dendrite‐free Li plating. The g‐C₃N₄/CC as an anode scaffold enables extraordinary cycling stability for over 1500 h with a small overpotential of ≈80 mV at 2 mA cm^?2. Furthermore, prominent battery performance is also demonstrated in a full cell (Li/g‐C₃N₄/CC as anode and LiCoO₂ as cathode) with high Coulombic efficiency of 99.4% over 300 cycles.     

Research on Advanced Materials for Li‐ion Batteries

In order to address power and energy demands of mobile electronics and electric cars, Li‐ion technology is urgently being optimized by using alternative materials. This article presents a review of our recent progress dedicated to the anode and cathode materials that have the potential to fulfil the crucial factors of cost, safety, lifetime, durability, power density, and energy density. Nanostructured inorganic compounds have been extensively investigated. Size effects revealed in the storage of lithium through micropores (hard carbon spheres), alloys (Si, SnSb), and conversion reactions (Cr₂O₃, MnO) are studied. The formation of nano/micro core–shell, dispersed composite, and surface pinning structures can improve their cycling performance. Surface coating on LiCoO₂ and LiMn₂O₄ was found to be an effective way to enhance their thermal and chemical stability and the mechanisms are discussed. Theoretical simulations and experiments on LiFePO₄ reveal that alkali metal ions and nitrogen doping into the LiFePO₄ lattice are possible approaches to increase its electronic conductivity and does not block transport of lithium ion along the 1D channel.     

Beyond Activated Carbon: Graphite‐Cathode‐Derived Li‐Ion Pseudocapacitors with High Energy and High Power Densities

Supercapacitors have aroused considerable attention due to their high power capability, which enables charge storage/output in minutes or even seconds. However, to achieve a high energy density in a supercapacitor has been a long‐standing challenge. Here, graphite is reported as a high‐energy alternative to the frequently used activated carbon (AC) cathode for supercapacitor application due to its unique Faradaic pseudocapacitive anion intercalation behavior. The graphite cathode manifests both higher gravimetric and volumetric energy density (498 Wh kg^?1 and 431.2 Wh l^?1) than an AC cathode (234 Wh kg^?1 and 83.5 Wh l^?1) with peak power densities of 43.6 kW kg^?1 and 37.75 kW l^?1. A new type of Li‐ion pseudocapacitor (LIpC) is thus proposed and demonstrated with graphite as cathode and prelithiated graphite or Li₄Ti₅O₁₂ (LTO) as anode. The resultant graphite–graphite LIpCs deliver high energy densities of 167–233 Wh kg^?1 at power densities of 0.22–21.0 kW kg^?1 (based on active mass in both electrodes), much higher than 20–146 Wh kg^?1 of AC‐derived Li‐ion capacitors and 23–67 Wh kg^?1 of state‐of‐the‐art metal oxide pseudocapacitors. Excellent rate capability and cycling stability are further demonstrated for LTO‐graphite LIpCs.     

High‐Coulombic‐Efficiency Carbon/Li Clusters Composite Anode without Precycling or Prelithiation

Lithium metal has attracted much research interest as a possible anode material for high‐energy‐density lithium‐ion batteries in recent years. However, its practical use is severely limited by uncontrollable deposition, volume expansion, and dendrite formation. Here, a metastable state of Li, Li cluster, that forms between LiC₆ and Li dendrites when over‐lithiating carbon cloth (CC) is discovered. The Li clusters with sizes in the micrometer and submicrometer scale own outstanding electrochemical reversibility between Li⁺ and Li, allowing the CC/Li clusters composite anode to demonstrate a high first‐cycle coulombic efficiency (CE) of 94.5% ± 1.0% and a stable CE of 99.9% for 160 cycles, which is exceptional for a carbon/lithium composite anode. The CC/Li clusters composite anode shows a high capacity of 3 mAh cm^?2 contributed by both Li⁺ intercalation and Li‐cluster formation, and excellent cycling stability with a signature sloping voltage profile. Furthermore, the CC/Li clusters composite anode can be assembled into full cells without precycling or prelithiation. The full cells containing bare CC as the anode and excessive LiCoO₂ as the cathode exhibit high specific capacity and good cyclic stability in 200 cycles, stressing the advantage of controlled formation of Li clusters.     

Ultralong Lifespan and Ultrafast Li Storage: Single‐Crystal LiFePO4 Nanomeshes

A novel LiFePO₄ material, in the shape of a nanomesh, has been rationally designed and synthesized based on the low crystal‐mismatch strategy. The LiFePO₄ nanomesh possesses several advantages in morphology and crystal structure, including a mesoporous structure, its crystal orientation that is along the [010] direction, and a shortened Li‐ion diffusion path. These properties are favorable for their application as cathode in Li‐ion batteries, as these will accelerate the Li‐ion diffusion rate, improve the Li‐ion exchange between the LiFePO₄ nanomesh and the electrolyte, and reduce the Li‐ion capacitive behavior during Li intercalation. So the LiFePO₄ nanomesh exhibits a high specific capacity, enhanced rate capability, and strengthened cyclability. The method developed here can also be extended to other similar systems, for instance, LiMnPO₄, LiCoPO₄, and LiNiPO₄, and may find more applications in the designed synthesis of functional materials.     

A Silica‐Aerogel‐Reinforced Composite Polymer Electrolyte with High Ionic Conductivity and High Modulus

High‐energy all‐solid‐state lithium (Li) batteries have great potential as next‐generation energy‐storage devices. Among all choices of electrolytes, polymer‐based systems have attracted widespread attention due to their low density, low cost, and excellent processability. However, they are generally mechanically too weak to effectively suppress Li dendrites and have lower ionic conductivity for reasonable kinetics at ambient temperature. Herein, an ultrastrong reinforced composite polymer electrolyte (CPE) is successfully designed and fabricated by introducing a stiff mesoporous SiO₂ aerogel as the backbone for a polymer‐based electrolyte. The interconnected SiO₂ aerogel not only performs as a strong backbone strengthening the whole composite, but also offers large and continuous surfaces for strong anion adsorption, which produces a highly conductive pathway across the composite. As a consequence, a high modulus of ≈0.43 GPa and high ionic conductivity of ≈0.6 mS cm^?1 at 30 °C are simultaneously achieved. Furthermore, LiFePO₄–Li full cells with good cyclability and rate capability at ambient temperature are obtained. Full cells with cathode capacity up to 2.1 mAh cm^?2 are also demonstrated. The aerogel‐reinforced CPE represents a new design principle for solid‐state electrolytes and offers opportunities for future all‐solid‐state Li batteries.     

Exploring Sodium‐Ion Storage Mechanism in Hard Carbons with Different Microstructure Prepared by Ball‐Milling Method

Hard carbon is considered as one of the most promising anodes in sodium‐ion batteries due to its high capacity, low cost, and abundant resources. However, the available capacity and low initial Coulombic efficiency (ICE) limits the practical application of hard carbon anode. This issue results from the unclear understanding of the Na⁺ storage mechanism in hard carbon. In this work, a series of hard carbons with different microstructures are synthesized through an “up to down” approach by using a simple ball‐milling method to illustrate the sodium‐ion storage mechanism. The results demonstrate that ball‐milled hard carbon with more defects and smaller microcrystalline size shows less low‐potential‐plateau capacity and lower ICE, which provides further evidence to the “adsorption–insertion” mechanism. This work might give a new perspective to design hard carbon material with a proper structure for efficient sodium‐ion storage to develop high‐performance sodium‐ion batteries.     

Dual‐Phase Single‐Ion Pathway Interfaces for Robust Lithium Metal in Working Batteries

The lithium (Li) metal anode is confronted by severe interfacial issues that strongly hinder its practical deployment. The unstable interfaces directly induce unfavorable low cycling efficiency, dendritic Li deposition, and even strong safety concerns. An advanced artificial protective layer with single‐ion pathways holds great promise for enabling a spatially homogeneous ionic and electric field distribution over Li metal surface, therefore well protecting the Li metal anode during long‐term working conditions. Herein, a robust dual‐phase artificial interface is constructed, where not only the single‐ion‐conducting nature, but also high mechanical rigidity and considerable deformability can be fulfilled simultaneously by the rational integration of a garnet Al‐doped Li_6.75La₃Zr_1.75Ta_0.25O₁₂‐based bottom layer and a lithiated Nafion top layer. The as‐constructed artificial solid electrolyte interphase is demonstrated to significantly stabilize the repeated cell charging/discharging process via regulating a facile Li‐ion transport and a compact Li plating behavior, hence contributing to a higher coulombic efficiency and a considerably enhanced cyclability of lithium metal batteries. This work highlights the significance of rational manipulation of the interfacial properties of a working Li metal anode and affords fresh insights into achieving dendrite‐free Li deposition behavior in a working battery.     

A Scalable Approach to Dendrite‐Free Lithium Anodes via Spontaneous Reduction of Spray‐Coated Graphene Oxide Layers

Li‐metal batteries (LiMBs) are experiencing a renaissance; however, achieving scalable production of dendrite‐free Li anodes for practical application is still a formidable challenge. Herein, a facile and universal method is developed to directly reduce graphene oxide (GO) using alkali metals (e.g., Li, Na, and K) in moderate conditions. Based on this innovation, a spontaneously reduced graphene coating can be designed and modulated on a Li surface (SR‐G‐Li). The symmetrical SR‐G‐Li|SR‐G‐Li cell can run up to 1000 cycles at a high practical current density of 5 mA cm^?2 without a short circuit, demonstrating one of the longest lifespans reported with LiPF₆‐based carbonate electrolytes. More significantly, a practically scalable paradigm is established to fabricate dendrite‐free Li anodes by spraying a GO layer on the Li anode surface for large‐scale production of LiFePO₄/Li pouch cells, reflected by the continuous manufacturing of the SR‐G‐Li anodes based on the roll‐to‐roll technology. The strategy provides new commercial opportunities to both LiMBs and graphene.     

All‐Solid‐State Batteries with a Limited Lithium Metal Anode at Room Temperature using a Garnet‐Based Electrolyte

Metallic lithium (Li), considered as the ultimate anode, is expected to promise high‐energy rechargeable batteries. However, owing to the continuous Li consumption during the repeated Li plating/stripping cycling, excess amount of the Li metal anode is commonly utilized in lithium‐metal batteries (LMBs), leading to reduced energy density and increased cost. Here, an all‐solid‐state lithium‐metal battery (ASSLMB) based on a garnet‐oxide solid electrolyte with an ultralow negative/positive electrode capacity ratio (N/P ratio) is reported. Compared with the counterpart using a liquid electrolyte at the same low N/P ratios, ASSLMBs show longer cycling life, which is attributed to the higher Coulombic efficiency maintained during cycling. The effect of the species of the interface layer on the cycling performance of ASSLMBs with low N/P ratio is also studied. Importantly, it is demonstrated that the ASSLMB using a limited Li metal anode paired with a LiFePO₄ cathode (5.9 N/P ratio) delivers a stable long‐term cycling performance at room temperature. Furthermore, it is revealed that enhanced specific energies for ASSLMBs with low N/P ratios can be further achieved by the use of a high‐voltage or high mass‐loading cathode. This study sheds light on the practical high‐energy all‐solid‐state batteries under the constrained condition of a limited Li metal anode.     

3D Printed High‐Performance Lithium Metal Microbatteries Enabled by Nanocellulose

Batteries constructed via 3D printing techniques have inherent advantages including opportunities for miniaturization, autonomous shaping, and controllable structural prototyping. However, 3D‐printed lithium metal batteries (LMBs) have not yet been reported due to the difficulties of printing lithium (Li) metal. Here, for the first time, high‐performance LMBs are fabricated through a 3D printing technique using cellulose nanofiber (CNF), which is one of the most earth‐abundant biopolymers. The unique shear thinning properties of CNF gel enables the printing of a LiFePO₄ electrode and stable scaffold for Li. The printability of the CNF gel is also investigated theoretically. Moreover, the porous structure of the CNF scaffold also helps to improve ion accessibility and decreases the local current density of Li anode. Thus, dendrite formation due to uneven Li plating/stripping is suppressed. A multiscale computational approach integrating first‐principle density function theory and a phase‐field model is performed and reveals that the porous structures have more uniform Li deposition. Consequently, a full cell built with a 3D‐printed Li anode and a LiFePO₄ cathode exhibits a high capacity of 80 mA h g^?1 at a charge/discharge rate of 10 C with capacity retention of 85% even after 3000 cycles.     

Self‐Supporting,Flexible, Additive‐Free,and Scalable Hard Carbon Paper Self‐Interwoven by 1D Microbelts: Superb Room/Low‐Temperature Sodium Storage and Working Mechanism

Hard carbon is regarded as a promising anode material for sodium‐ion batteries (SIBs). However, it usually suffers from the issues of low initial Coulombic efficiency (ICE) and poor rate performance, severely hindering its practical application. Herein, a flexible, self‐supporting, and scalable hard carbon paper (HCP) derived from scalable and renewable tissue is rationally designed and prepared as practical additive‐free anode for room/low‐temperature SIBs with high ICE. In ether electrolyte, such HCP achieves an ICE of up to 91.2% with superior high‐rate capability, ultralong cycle life (e.g., 93% capacity retention over 1000 cycles at 200 mA g^?1) and outstanding low‐temperature performance. Working mechanism analyses reveal that the plateau region is the rate‐determining step for HCP with a lower electrochemical reaction kinetics, which can be significantly improved in ether electrolyte.     

Novel Co2VO4 Anodes Using Ultralight 3D Metallic Current Collector and Carbon Sandwiched Structures for High‐Performance Li‐Ion Batteries

A novel spinel Co₂VO₄ is studied as the Li‐ion battery anode material and it is sandwiched with a 3D ultralight porous current collector (PCC) and amorphous carbon. Co₂VO₄ demonstrates the high capacity and excellent cyclability because of the mixed lithium storage mechanisms. The 3D composite structure requires no binders and replaces the conventional current collector (Cu foil) with a 3D ultralight porous metal scaffold, yielding the high electrode‐based capacity. Such a novel composite anode also enables the close adhesion of Co₂VO₄ to the PCC scaffold. The resulting monolithic electrode has the rapid electron pathway and stable mechanical properties, which lead to the excellent rate capabilities and cycling properties. At a current density of 1 A g^?1, the PCC and carbon sandwiched Co₂VO₄ anode is able to deliver a stable reversible capacity of about 706.8 mAh g^?1 after 1000 cycles. Generally, this study not only develops a new Co₂VO₄ anode with high capacity and good cyclability, but also demonstrates an alternative approach to improve the electrochemical properties of high capacity anode materials by using ultralight porous metallic current collector instead of heavy copper foil.     

Bulk Nanostructured Materials Design for Fracture‐Resistant Lithium Metal Anodes

Li metal is an ideal anode for next‐generation batteries because of its high theoretical capacity and low potential. However, the unevenly distributed stress in Li metal anodes (LMAs) induced by volume fluctuation may cause the electrode to fracture easily, especially during high‐rate plating/stripping processes. Here fracture‐resistant LMAs using the concept of bulk nanostructured materials are designed via a metallurgical process. In bulk nanostructured Li (BNL), ionic conducting phases exist at grain boundaries, which promote Li⁺ transport. The refined Li grain size and precipitation hardening in BNL enhances the mechanical strength and fatigue endurance, alleviating the unevenly distributed stress and preventing electrode pulverization. Density functional theory is used to investigate the binding energy between Li and various kinds of oxides and SiO₂ is found to be optimal additive among screened oxides. BNL has 91% of the theoretical capacity of Li metal. In full cells with BNL anode, LiFePO₄ could deliver capacity of 90 mAh g^?1 at 10C, an order of magnitude higher than that in full cells with Li foil anode. This strategy is expected to pave the way for fracture‐resistant LMAs in high‐rate cycling with maximum capacity.     

Nonaqueous Hybrid Lithium‐Ion and Sodium‐Ion Capacitors

Hybrid metal‐ion capacitors (MICs) (M stands for Li or Na) are designed to deliver high energy density, rapid energy delivery, and long lifespan. The devices are composed of a battery anode and a supercapacitor cathode, and thus become a tradeoff between batteries and supercapacitors. In the past two decades, tremendous efforts have been put into the search for suitable electrode materials to overcome the kinetic imbalance between the battery‐type anode and the capacitor‐type cathode. Recently, some transition‐metal compounds have been found to show pseudocapacitive characteristics in a nonaqueous electrolyte, which makes them interesting high‐rate candidates for hybrid MIC anodes. Here, the material design strategies in Li‐ion and Na‐ion capacitors are summarized, with a focus on pseudocapacitive oxide anodes (Nb₂O₅, MoO₃, etc.), which provide a new opportunity to obtain a higher power density of the hybrid devices. The application of Mxene as an anode material of MICs is also discussed. A perspective to the future research of MICs toward practical applications is proposed to close.     

Hierarchically Nanoporous 3D Assembly Composed of Functionalized Onion‐Like Graphitic Carbon Nanospheres for Anode‐Minimized Li Metal Batteries

Despite the recent attention for Li metal anode (LMA) with high theoretical specific capacity of ≈ 3860 mA h g^?1, it suffers from not enough practical energy densities and safety concerns originating from the excessive metal load, which is essential to compensate for the loss of Li sources resulting from their poor coulombic efficiencies (CEs). Therefore, the development of high‐performance LMA is needed to realize anode‐minimized Li metal batteries (LMBs). In this study, high‐performance LMAs are produced by introducing a hierarchically nanoporous assembly (HNA) composed of functionalized onion‐like graphitic carbon building blocks, several nanometers in diameter, as a catalytic scaffold for Li‐metal storage. The HNA‐based electrodes lead to a high Li ion concentration in the nanoporous structure, showing a high CE of ≈ 99.1%, high rate capability of 12 mA cm^?2, and a stable cycling behavior of more than 750 cycles. In addition, anode‐minimized LMBs are achieved using a HNA that has limited Li content ( ≈ 0.13 mg cm^?2), corresponding to 6.5% of the cathode material (commercial NCM622 ( ≈ 2 mg cm^?2)). The LMBs demonstrate a feasible electrochemical performance with high energy and power densities of ≈ 510 Wh kg_electrode^?1 and ≈ 2760 W kg_electrode^?1, respectively, for more than 100 cycles.     

In‐Plane Lithium Growth Enabled by Artificial Nitrate‐Rich Layer: Fast Deposition Kinetics and Desolvation/Adsorption Mechanism

An artificial lithium‐nitrate (LiNO₃)‐rich layer (LN‐RL) is developed to address dendritic lithium (Li) growth by a fusing–infusing strategy, in which LiNO₃ is loaded into stainless steel mesh and a Li‐metal anode (LN‐RL@Li) is obtained by casting this LN‐RL onto Li foil. The LN‐RL enables fast Li deposition kinetics in carbonates and endows LN‐RL@Li with excellent cycleability. The underneath mechanism on the contribution of LN‐RL is uncovered by detailed characterizations combining with theoretical simulations. The LN‐RL promotes the desolvation and capacitive adsorption of Li ions and induces in‐plane Li growth along the edges of preplated Li with planar morphology. The improved cycleability of LN‐RL(@Li) is demonstrated by Li∥Cu cell that presents a coulombic efficiency of 97.2% after 280 cycles and Li∥Li cell that proceeds over 1000 h at 0.5 mA cm^?2 in carbonates. Additionally, the Li∥LiFePO₄ cell shows a capacity retention of 58% after 400 cycles at 1 C (1 C = 170 mA g^?1), compared to the 35% after 180 cycles for the control. This work presents not only a promising strategy for practical applications of Li‐metal batteries, but also a new understanding on the role of nitrate in Li plating/stripping kinetics.     

Prelithiated V2C MXene: A High‐Performance Electrode for Hybrid Magnesium/Lithium‐Ion Batteries by Ion Cointercalation

The pursuit of high reversible capacity and long cycle life for rechargeable batteries has gained extensive attention in recent years, and the development of applicable electrode materials is the key point. Herein, thanks to the preintercalation of lithium ions, a stable and highly conductive nanostructure of V₂C MXene is successfully fabricated via a facile self‐discharge mechanism, which provides open spaces for rapid ion diffusion and guarantees fast electron transport. Taking the prelithiated V₂C as electrode, an outstanding initial coulombic efficiency of 80% and an impressive capacity retention of ≈98% after 5000 charge/discharge cycles are achieved for lithium‐ion batteries. Especially, it demonstrates a fascinating reversible capacity of up to 230.3 mA h g^?1 at 0.02 A g^?1 and a long cycling life of 82% capacity retention over 480 cycles in the hybrid magnesium/lithium‐ion batteries. In addition, the Mg²⁺ and Li⁺ ions cointercalation mechanism of the prelithiated V₂C is elucidated through ex situ X‐ray diffraction and X‐ray photoelectron spectroscopy characterizations. This work not only offers an effective approach to compensate the large initial lithium loss of high‐capacity anode materials but also opens up a new and viable avenue to develop promising hybrid Mg/Li‐storage materials with eminent electrochemical performance.     

A High Energy and Power Li‐Ion Capacitor Based on a TiO2 Nanobelt Array Anode and a Graphene Hydrogel Cathode

A novel hybrid Li‐ion capacitor (LIC) with high energy and power densities is constructed by combining an electrochemical double layer capacitor type cathode (graphene hydrogels) with a Li‐ion battery type anode (TiO₂ nanobelt arrays). The high power source is provided by the graphene hydrogel cathode, which has a 3D porous network structure and high electrical conductivity, and the counter anode is made of free‐standing TiO₂ nanobelt arrays (NBA) grown directly on Ti foil without any ancillary materials. Such a subtle designed hybrid Li‐ion capacitor allows rapid electron and ion transport in the non‐aqueous electrolyte. Within a voltage range of 0.0?3.8 V, a high energy of 82 Wh kg^?1 is achieved at a power density of 570 W kg^?1. Even at an 8.4 s charge/discharge rate, an energy density as high as 21 Wh kg^?1 can be retained. These results demonstrate that the TiO₂ NBA//graphene hydrogel LIC exhibits higher energy density than supercapacitors and better power density than Li‐ion batteries, which makes it a promising electrochemical power source.