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In this perspective, we present an overview of the research and advancement of lignocellulose-derived hard carbon anodes and their pivotal role in the commercialization of sodium-ion batteries. Hard carbon anodes, sourced from lignocellulosic biomasses, exhibit considerable promise due to their widespread availability, economical viability, and environmentally friendly attributes with zero carbon-dioxide emissions. Given the intricate compositions and composite nature of lignocellulosic materials, it becomes imperative to prioritize factors crucial for the fabrication of hard carbon anodes that exhibit enhanced sodium-ion storage capabilities. Thus, our study offers an extensive overview of the structure and performance nuances of hard carbon anodes derived from cellulose, hemicellulose, and lignin. Furthermore, it delves into the fundamental principles governing synthesis methodologies and confronts the challenges inherent in producing lignocellulose-derived hard carbon anodes tailored specifically for sodium-ion batteries. Highlights: • Lignocellulose is a promising low-cost precursor for the hard carbon anodes in sodium-ion batteries. • Chemical, crystalline, components, and multi-dimensional structures of lignocellulose influence the structure and performance of hard carbon anodes. • Engineering methodologies tuning the microstructures of lignocellulose could change the intrinsic structure and performances of hard carbon anodes. • New methods also need to consider the principles of green chemistry and sustainable development. [ABSTRACT FROM AUTHOR]

Aqueous zinc (Zn) ion batteries (AZIBs) are regarded as one of the promising candidates for next‐generation electrochemical energy storage systems due to their low cost, high safety, and environmental friendliness. However, the commercialization of AZIBs has been severely restricted by the growth of dendrite at the Zn metal anode. Tailoring the planar‐structured Zn anodes into three‐dimensional (3D) structures has proven to be an effective way to modulate the plating/stripping behavior of Zn anodes, resulting in the suppression of dendrite formation. This review provides an up‐to‐date review of 3D structured Zn metal anodes, including working principles, design, current status, and future prospects. We aim to give the readers a comprehensive understanding of 3D‐structured Zn anodes and their effective usage to enhance AZIB performance. [ABSTRACT FROM AUTHOR]

Dendritic deposition and side reactions have been long‐standing interfacial challenges of Zn anode, which have prevented the development of practical aqueous zinc‐based batteries. Herein, an oxygen vacancy‐rich CeO2 aerogel (VAG‐Ce) interface layer that simultaneously integrates Zn2+ selectivity, porosity, and is lightweight is reported as a new strategy to achieve dendrite‐free and corrosion‐free Zn anodes. The well‐defined and uniform nanochannels of VAG‐Ce can act as ion sieves that redistribute Zn2+ at the Zn anode surface by regulating Zn2+ flux, leading to uniform Zn deposition and significantly suppressing dendrite growth. Importantly, the abundant oxygen vacancies exposed on VAG‐Ce surface can strongly capture SO42−, forming a negatively charged layer that can attract Zn2+ and accelerate the Zn2+ migration kinetics, while the subsequent repulsion of additional anions can effectively suppress the generation of (Zn4SO4(OH)6·xH2O) byproducts, thereby realizing very stable Zn anodes. Consequently, VAG‐Ce modified Zn anode (VAG‐Ce@Zn) enables a long‐term lifespan over 4000 h at 4 mA cm−2 and a record‐high cycle life of 1200 h is achieved under an ultrahigh 85% Zn utilization at 8 mA cm−2, which enables excellent capacity retention and cycling performance of VAG@Zn/MnO2 cells. This work contributes an innovative design concept by introducing oxygen vacancy‐rich aerogels and provides a new horizon for stabilizing Zn anode for large‐scale energy storage. [ABSTRACT FROM AUTHOR]

Carbonaceous materials are promising anodes for practical potassium‐ion batteries, but fail to meet the requirements for durability and high capacities at low potentials. Herein, we constructed a durable carbon anode for high‐energy‐density K‐ion full cells by a preferential pyrolysis strategy. Utilizing S and N volatilization from a π–π stacked supermolecule, the preferential pyrolysis process introduces low‐potential active sites of sp2 hybridized carbon and carbon vacancies, endowing a low‐potential "vacancy‐adsorption/intercalation" mechanism. The as‐prepared carbon anode exhibits a high capacity of 384.2 mAh g−1 (90 % capacity locates below 1 V vs. K/K+), which contributes to a high energy density of 163 Wh kg−1 of K‐ion full battery. Moreover, abundant vacancies of carbon alleviate volume variation, boosting the cycling stability over 14 000 cycles (8400 h). Our work provides a new synthesis approach for durable carbon anodes of K‐ion full cells with high energy densities. [ABSTRACT FROM AUTHOR]

Hard carbons have attracted increased interest as an alternative of graphite for the anodes of potassium‐ion batteries (PIBs). However, the practical applications of hard carbon anodes are hampered by their low capacities, high potential platforms, and large potential hysteresis. Hard carbons coupled with graphitic nanodomains can achieve stable potassium‐ion storage behaviors with low potential platforms and low potential hysteresis. Herein, the crystalline lattice in hard carbon anodes is tuned by incorporating graphene oxide in renewable lignin precursors. The modified hard carbon (i.e., QLGC) anodes show graphitized nanodomains in the carbon matrix with an expanded interlayer spacing (0.42 nm) in the amorphous regions, which results in a stable potassium‐ion (de)intercalation behavior. Thus, the QLGC anodes exhibit a high capacity of 164 mAh g−1 with low potential hysteresis in the low potential platform region. Moreover, the QLGC anode delivered a highly stabilized capacity of 283 mAh g−1 at 50 mA g−1, a high‐rate capability, and stable cycling performance. Furthermore, the charge storage mechanisms of QLGC anode are elucidated by electro‐kinetic analysis and ex/in situ physicochemical characterizations. This study opens a new avenue for designing hard carbon anodes with engineered crystalline lattices toward practical PIBs. [ABSTRACT FROM AUTHOR]

Highlights: The N/S co-doped lignin-derived porous carbon (NSLPCs) with ultra-high heteroatom doping was prepared through a novel supramolecule-mediated pyrolysis strategy. Covalently bonded graphitic carbon/amorphous carbon intermediates induce the formation of high heteroatom doping. The high heteroatom doping of NSLPC could provide abundant defective active sites for the adsorption of K+. Amorphous carbons are promising anodes for high-rate potassium-ion batteries. Most low-temperature annealed amorphous carbons display unsatisfactory capacities. Heteroatom-induced defect engineering of amorphous carbons could enhance their reversible capacities. Nevertheless, most lignocellulose biomasses lack heteroatoms, making it a challenge to design highly heteroatom-doped carbons (> 10 at%). Herein, we report a new preparation strategy for amorphous carbon anodes. Nitrogen/sulfur co-doped lignin-derived porous carbons (NSLPC) with ultra-high nitrogen doping levels (21.6 at% of N and 0.8 at% of S) from renewable lignin biomacromolecule precursors were prepared through a supramolecule-mediated pyrolysis strategy. This supermolecule/lignin composite decomposes forming a covalently bonded graphitic carbon/amorphous carbon intermediate product, which induces the formation of high heteroatom doping in the obtained NSLPC. This unique pyrolysis chemistry and high heteroatom doping of NSLPC enable abundant defective active sites for the adsorption of K+ and improved kinetics. The NSLPC anode delivered a high reversible capacity of 419 mAh g‒1 and superior cycling stability (capacity retention of 96.6% at 1 A g‒1 for 1000 cycles). Potassium-ion hybrid capacitors assembled by NSLPC anode exhibited excellent cycling stability (91% capacity retention for 2000 cycles) and a high energy density of 71 Wh kg–1 at a power density of 92 W kg–1. [ABSTRACT FROM AUTHOR]

Alkali metals (i.e., Li, Na, and K) are promising anode materials for next‐generation high‐energy‐density batteries due to their superior theoretical specific capacities and low electrochemical potentials. However, the uneven current and ion distribution on the anode surface probably induces undesirable dendrite growth, which leads to significant safety hazards and severely hinders the commercialization of alkali metal anodes. A smart and versatile strategy that can accommodate alkali metals into porous metal current collectors (PMCCs) has been well established to resolve the issues as well as to promote the practical applications of alkali metal anodes. Moreover, the proposal of PMCCs can meet the requirement of the dendrite‐free battery fabrication industry, while the electrode material loading exactly needs the metal current collector component as well. Here, a systematic survey on advanced PMCCs for Li, Na, and K alkali metal anodes is presented, including their development timeline, categories, fabrication methods, and working mechanism. On this basis, some significant methodology advances to control pore structure, surface area, surface wettability, and mechanical properties are systematically summarized. Further, the existing issues and the development prospects of PMCCs to improve anode performance in alkali metal batteries are discussed. [ABSTRACT FROM AUTHOR]

Organic anodes have attracted increasing attention for alkali metal ion batteries. In this work, we discovered that cyclized polyacrylonitrile (cPAN) can serve as an excellent anode for alkali metal ion batteries. Upon activation cycling, as an anode of lithium‐ion battery, cPAN exhibits a reversible capacity as high as 1238 mAh g−1 under a current density of 50 mA g−1. Based on electrochemical experiments and first‐principles calculations, it is demonstrated that the hexagonal carbon ring, piperidine ring, and pyridine nitrogen in ladder cPAN are the main active sites for lithium‐ion storage. cPAN displays a unique potential‐dependent solid electrolyte interphase formation from 0.1 to 0.01 V vs. Li/Li+. It also displays decent performance as an anode in SIBs and PIBs. [ABSTRACT FROM AUTHOR]

The pursuit of more efficient carbon‐based anodes for sodium‐ion batteries (SIBs) prepared from facile and economical methods is a very important endeavor. Based on the crystallinity difference within carbon materials, herein, a low‐temperature selective burning method is developed for preparing oxygen and nitrogen codoped holey graphene aerogel as additive‐free anode for SIBs. By selective burning of a mixture of graphene and low‐crystallinity carbon at 450 °C in air, an elastic porous graphene monolith with abundant holes on graphene sheets and optimized crystallinity is obtained. These structural characteristics lead to an additive‐free electrode with fast charge (ions and electrons) transfer and more abundant Na+ storage active sites. Moreover, the heteroatom oxygen/nitrogen doping favors large interlayer distance for rapid Na+ insertion/extraction and provides more active sites for high capacitive contribution. The optimized sample exhibits superior sodium‐ion storage capability, i.e., high specific capacity (446 mAh g−1 at 0.1 A g−1), ultrahigh rate capability (189 mAh g−1 at 10 A g−1), and long cycle life (81.0% capacity retention after 2000 cycles at 5 A g−1). This facile and economic strategy might be extended to fabricating other superior carbon‐based energy storage materials. [ABSTRACT FROM AUTHOR]

The limited potassium‐ion intercalation capacity of graphite hampers development of potassium‐ion batteries (PIB). Edge‐nitrogen doping is an effective approach to enhance K‐ion storage in carbonaceous materials. One shortcoming is the lack of precise control over producing the edge‐nitrogen configuration. Here, a molecular‐scale copolymer pyrolysis strategy is used to precisely control edge‐nitrogen doping in carbonaceous materials. This process results in defect‐rich, edge‐nitrogen doped carbons (ENDC) with a high nitrogen‐doping level (up to 10.5 at %) and a high edge‐nitrogen ratio (87.6 %). The optimized ENDC exhibits a high reversible capacity of 423 mAh g−1, a high initial Coulombic efficiency of 65 %, superior rate capability, and long cycle life (93.8 % retention after three months). This strategy can be extended to design other edge‐heteroatom‐rich carbons through pyrolysis of copolymers for efficient storage of various mobile ions. [ABSTRACT FROM AUTHOR]

Abstract: Conventional graphite anodes can hardly intercalate sodium (Na) ions, which poses a serious challenge for developing Na‐ion batteries. This study details a novel method that involves single‐step laser‐based transformation of urea‐containing polyimide into an expanded 3D graphene anode, with simultaneous doping of high concentrations of nitrogen (≈13 at%). The versatile nature of this laser‐scribing approach enables direct bonding of the 3D graphene anode to the current collectors without the need for binders or conductive additives, which presents a clear advantage over chemical or hydrothermal methods. It is shown that these conductive and expanded 3D graphene structures perform exceptionally well as anodes for Na‐ion batteries. Specifically, an initial coulombic efficiency (CE) up to 74% is achieved, which exceeds that of most reported carbonaceous anodes, such as hard carbon and soft carbon. In addition, Na‐ion capacity up to 425 mAh g−1 at 0.1 A g−1 has been achieved with excellent rate capabilities. Further, a capacity of 148 mAh g−1 at a current density of 10 A g−1 is obtained with excellent cycling stability, opening a new direction for the fabrication of 3D graphene anodes directly on current collectors for metal ion battery anodes as well as other potential applications. [ABSTRACT FROM AUTHOR]

Metal oxides synthesized by the solvothermal approach have widespread applications, while their nanostructure control remains challenging because their reaction mechanism is still not fully understood. Herein, it is demonstrated how the competitive relation between Ostwald ripening and surface charging during solvothermal synthesis is crucial to engineering high‐quality metal (oxide)–carbon nanomaterials. Using SnO2 as a case study, a new type of hollow SnO2–C hybrid nanoparticles is synthesized consisting of core–shell structured SnO2@C nanodots (which has not been previously reported). This new anode material exhibits extremely high lithium storage capacity of 1225 and 955 mAh g−1 at 200 and 500 mA g−1, respectively, and excellent cycling stability. In addition, full‐battery cells are constructed combining SnO2–C anode with Ni‐rich cathode, which can be charged to a higher voltage compared to commercial graphite anode and still demonstrate extraordinary rate performance. This study provides significant insight into the largely unexplored reaction mechanism during solvothermal synthesis, and demonstrates how such understanding can be used to achieve high‐performance metal (oxide)–C anodes for rechargeable batteries. [ABSTRACT FROM AUTHOR]

The application of graphite anodes in potassium‐ion batteries (KIB) is limited by the large variation in lattice volume and the low diffusion coefficient of potassium ions during (de)potassiation. This study demonstrates nitrogen‐doped, defect‐rich graphitic nanocarbons (GNCs) as high‐performance KIB anodes. The GNCs with controllable defect densities are synthesized by annealing an ethylenediaminetetraacetic acid nickel coordination compound. The GNCs show better performance than the previously reported thin‐walled graphitic carbonaceous materials such as carbon nanocages and nanotubes. In particular, the GNC prepared at 600 °C shows a stabilized capacity of 280 mAh g−1 at 50 mA g−1, robust rate capability, and long cycling life due to its high‐nitrogen‐doping, short‐range‐ordered, defect‐rich graphitic structure. A high capacity of 189 mAh g−1 with a long cycle life over 200 cycles is demonstrated at a current density of 200 mA g−1. Further, it is confirmed that the potassium ion storage mechanism of GNCs is different from that of graphite using multiple characterization methods. Specifically, the GNCs with numerous defects provide more active sites for the potassiation process, which results in a final discharge product with short‐range order. This study opens a new pathway for designing graphitic carbonaceous materials for KIB anodes. [ABSTRACT FROM AUTHOR]

The current Na+ storage performance of carbon‐based materials is still hindered by the sluggish Na+ ion transfer kinetics and low capacity. Graphene and its derivatives have been widely investigated as electrode materials in energy storage and conversion systems. However, as anode materials for sodium‐ion batteries (SIBs), the severe π–π restacking of graphene sheets usually results in compact structure with a small interlayer distance and a long ion transfer distance, thus leading to low capacity and poor rate capability. Herein, partially reduced holey graphene oxide is prepared by simple H2O2 treatment and subsequent low temperature reduction of graphene oxide, leading to large interlayer distance (0.434 nm), fast ion transport, and larger Na+ storage space. The partially remaining oxygenous groups can also contribute to the capacity by redox reaction. As anode material for SIBs, the optimized electrode delivers high reversible capacity, high rate capability (365 and 131 mAh g−1 at 0.1 and 10 A g−1, respectively), and good cycling performance (163 mAh g−1 after 3000 cycles at a current density of 2 A g−1), which is among the best reported performances for carbon‐based SIB anodes. Partially reduced holey graphene oxide is prepared by low temperature reduction of holey graphene oxide. The large interlayer distance, short ion transfer distance, increased ion insertion/extraction sites, and residual oxygenous groups endow partially reduced holey graphene oxide with high sodium ion storage capability. This approach provides a facile and scalable strategy to produce high‐performance anode materials for sodium ion batteries. [ABSTRACT FROM AUTHOR]

We have systematically changed the number of atomic layers stacked in 2D SnO nanosheet anodes and studied their sodium ion battery (SIB) performance. The results indicate that as the number of atomic SnO layers in a sheet decreases, both the capacity and cycling stability of the Na ion battery improve. The thinnest SnO nanosheet anodes (two to six SnO monolayers) exhibited the best performance. Specifically, an initial discharge and charge capacity of 1072 and 848 mAh g-1 were observed, respectively, at 0.1 A g-1. In addition, an impressive reversible capacity of 665 mAh g-1 after 100 cycles at 0.1 A g-1 and 452 mAh g-1 after 1000 cycles at a high current density of 1.0 A g-1 was observed, with excellent rate performance. As the average number of atomic layers in the anode sheets increased, the battery performance degraded significantly. For example, for the anode sheets with 10-20 atomic layers, only a reversible capacity of 389 mAh g-1 could be obtained after 100 cycles at 0.1 A g-1. Density functional theory calculations coupled with experimental results were used to elucidate the sodiation mechanism of the SnO nanosheets. This systematic study of monolayer-dependent physical and electrochemical properties of 2D anodes shows a promising pathway to engineering and mitigating volume changes in 2D anode materials for sodium ion batteries. It also demonstrates that ultrathin SnO nanosheets are promising SIB anode materials with high specific capacity, stable cyclability, and excellent rate performance. [ABSTRACT FROM AUTHOR]