Enhanced Capacity and Rate Capability of Nitrogen/Oxygen Dual-Doped Hard Carbon in Capacitive Potassium-Ion Storage

Yoo H.D., Liang Y., Dong H., Lin J., Wang H., Liu Y., Ma L., Wu T., Li Y., Ru Q., Jing Y., An Q., Zhou W., Guo J., Lu J., et. al.

Magnesium rechargeable batteries potentially offer high-energy density, safety, and low cost due to the ability to employ divalent, dendrite-free, and earth-abundant magnesium metal anode. Despite recent progress, further development remains stagnated mainly due to the sluggish scission of magnesium-chloride bond and slow diffusion of divalent magnesium cations in cathodes. Here we report a battery chemistry that utilizes magnesium monochloride cations in expanded titanium disulfide. Combined theoretical modeling, spectroscopic analysis, and electrochemical study reveal fast diffusion kinetics of magnesium monochloride cations without scission of magnesium-chloride bond. The battery demonstrates the reversible intercalation of 1 and 1.7 magnesium monochloride cations per titanium at 25 and 60 °C, respectively, corresponding to up to 400 mAh g−1 capacity based on the mass of titanium disulfide. The large capacity accompanies with excellent rate and cycling performances even at room temperature, opening up possibilities for a variety of effective intercalation hosts for multivalent-ion batteries.Magnesium rechargeable batteries potentially offer high-energy density, safety, and low cost. Here the authors show a battery that reversibly intercalates magnesium monochloride cations with excellent rate and cycle performances in addition to the large capacity.

Wu X., Leonard D.P., Ji X.

The ever-increasing demand for storing renewable energy sources calls for novel battery technologies that are of sustainably low levelized energy cost. Research into battery chemistry has evolved to a stage where a plethora of choices based on earth-abundant elements can be compared during their development. One of the emerging candidates is the nonaqueous potassium-ion battery. K-ion’s unique properties as a charge carrier have aroused intense interest in exploring high-performing cathode and anode materials for this battery. Rapid progress has been made, where leading candidates of electrodes have been proposed, i.e., hard carbon as anode and Prussian white analogues as cathode. In this new battery technology’s infancy, it is our opinion that the focus should be given to potentially scalable, inexpensive electrode materials and the understanding of their cycle-life-property correlations. It may be the ultralong cycle life that differentiates potassium-ion batteries from sodium-ion batteries in the futur...

Jian Z., Hwang S., Li Z., Hernandez A.S., Wang X., Xing Z., Su D., Ji X.

There exist tremendous needs for sustainable storage solutions for intermittent renewable energy sources, such as solar and wind energy. Thus, systems based on Earth-abundant elements deserve much attention. Potassium-ion batteries represent a promising candidate because of the abundance of potassium resources. As for the choices of anodes, graphite exhibits encouraging potassium-ion storage properties; however, it suffers limited rate capability and poor cycling stability. Here, nongraphitic carbons as K-ion anodes with sodium carboxymethyl cellulose as the binder are systematically investigated. Compared to hard carbon and soft carbon, a hard–soft composite carbon with 20 wt% soft carbon distributed in the matrix phase of hard carbon microspheres exhibits highly amenable performance: high capacity, high rate capability, and very stable long-term cycling. In contrast, pure hard carbon suffers limited rate capability, while the capacity of pure soft carbon fades more rapidly.

Jin Y., Li S., Kushima A., Zheng X., Sun Y., Xie J., Sun J., Xue W., Zhou G., Wu J., Shi F., Zhang R., Zhu Z., So K., Cui Y., et. al.

Full-cell cycling of a high density silicon-majority anode with 2× volumetric capacity of graphite and a stabilized coulombic efficiency exceeding 99.9%.

Huang M., Mi K., Zhang J., Liu H., Yu T., Yuan A., Kong Q., Xiong S.

Co–Zn/N–C polyhedral nanocages: porous bimetallic Co/Zn embedded N-doped carbon (Co–Zn/N–C) polyhedral nanocages have been synthesized through annealing a ZIF-8@ZIF-67 precursor for the first time. The excellent lithium-storage ability is attributed to the unique structure of Co–Zn/N–C.

Chao D., Liang P., Chen Z., Bai L., Shen H., Liu X., Xia X., Zhao Y., Savilov S.V., Lin J., Shen Z.X.

The abundant reserve and low cost of sodium have provoked tremendous evolution of Na-ion batteries (SIBs) in the past few years, but their performances are still limited by either the specific capacity or rate capability. Attempts to pursue high rate ability with maintained high capacity in a single electrode remains even more challenging. Here, an elaborate self-branched 2D SnS2 (B-SnS2) nanoarray electrode is designed by a facile hot bath method for Na storage. This interesting electrode exhibits areal reversible capacity of ca. 3.7 mAh cm-2 (900 mAh g-1) and rate capability of 1.6 mAh cm-2 (400 mAh g-1) at 40 mA cm-2 (10 A g-1). Improved extrinsic pseudocapacitive contribution is demonstrated as the origin of fast kinetics of an alloying-based SnS2 electrode. Sodiation dynamics analysis based on first-principles calculations, ex-situ HRTEM, in situ impedance, and in situ Raman technologies verify the S-edge effect on the fast Na+ migration and reversible and sensitive structure evolution during high-rate charge/discharge. The excellent alloying-based pseudocapacitance and unsaturated edge effect enabled by self-branched surface nanoengineering could be a promising strategy for promoting development of SIBs with both high capacity and high rate response.

Li Z., Zhang J., Guan B., Wang D., Liu L., Lou X.W.

Lithium–sulfur batteries show advantages for next-generation electrical energy storage due to their high energy density and cost effectiveness. Enhancing the conductivity of the sulfur cathode and moderating the dissolution of lithium polysulfides are two key factors for the success of lithium–sulfur batteries. Here we report a sulfur host that overcomes both obstacles at once. With inherent metallic conductivity and strong adsorption capability for lithium-polysulfides, titanium monoxide@carbon hollow nanospheres can not only generate sufficient electrical contact to the insulating sulfur for high capacity, but also effectively confine lithium-polysulfides for prolonged cycle life. Additionally, the designed composite cathode further maximizes the lithium-polysulfide restriction capability by using the polar shells to prevent their outward diffusion, which avoids the need for chemically bonding all lithium-polysulfides on the surfaces of polar particles. The promise of lithium-sulfur batteries with higher energy densities than lithium-ion is hindered by the insulating nature of sulfur and dissolution of polysulfides. Here the authors design titanium monoxide/carbon hollow nanospheres that overcome both obstacles, enabling improved electrochemical properties.

Zhao J., Zou X., Zhu Y., Xu Y., Wang C.

Exceptional cycling performance of graphite anode in K-ion batteries is demonstrated with a reversible capacity of 246 mAh g–1 and 89% retention of the initial capacity after 200 cycles. Although the graphite anode experiences huge volume change and worse kinetics during K intercalation/deintercalation, the cycling stability delivered in K-ion batteries is comparable to that of Li-ion batteries using the same graphite anode. The combination of excellent electrochemical performance, the abundance and wide availability of K in earth's crust, and the well-developed technology of the graphite anode make the K-ion battery very attractive for offering a low cost battery chemistry for large-scale energy storage applications.

Wan J., Shen F., Luo W., Zhou L., Dai J., Han X., Bao W., Xu Y., Panagiotopoulos J., Fan X., Urban D., Nie A., Shahbazian-Yassar R., Hu L.

Sodium-ion batteries (SIBs) have attracted a great deal of attention recently as an economic alternative to Li-ion batteries. Cost-efficient reduced graphene oxide (rGO) has been intensively studied as both an active material and a functional additive in SIBs. However, the sodiation–desodiation process in rGO is not fully understood. In this study, we investigate the interaction of the Na ion with rGO by in situ transmission electron microscopy (TEM). For the first time, we observe reversible Na metal cluster (with a diameter of >10 nm) deposition on a rGO surface, which we evidence with an atom-resolved high-resolution TEM image of Na metal. This discovery leads to a porous reduced graphene oxide SIB anode with record high reversible specific capacity around 450 mAh/g at 25 mA/g, a high rate performance of 200 mAh/g at 250 mA/g, and stable cycling performance up to 750 cycles. In addition, direct observation of irreversible formation of Na2O on rGO unveils the origin of the commonly observed low first Co...

Cohn A.P., Muralidharan N., Carter R., Share K., Oakes L., Pint C.L.

We report the first demonstration of potassium ion cointercalation into graphitic carbon electrodes including both natural graphite and multi-layered graphene in both diglyme and monoglyme based electrolytes.

Yu L., Yang J.F., Lou X.W.

Metal-organic frameworks (MOFs) have been intensively used as the templates/precursors to synthesize complex hollow structures for various energy-related applications. Herein we report a facile two-step diffusion-controlled strategy to generate novel MOFs derived hierarchical hollow prisms composed of Nanosized CoS2 bubble-like subunits. Uniform zeolitic imidazolate framework-67 (ZIF-67) hollow prisms assembled by interconnected nanopolyhedra are first synthesized via a transformation process. Afterwards, these ZIF-67 building blocks are converted into CoS2 bubble-like hollow particles to form the complex hollow prisms through a sulfidation reaction with an additional annealing treatment. When evaluated as an electrode material for lithium-ion batteries, the as-obtained CoS2 nanobubble hollow prisms show remarkable electrochemical performance with good rate capability and long cycle life.

Xing Z., Qi Y., Jian Z., Ji X.

We synthesized a new type of carbon-polynanocrystalline graphite-by chemical vapor deposition on a nanoporous graphenic carbon as an epitaxial template. This carbon is composed of nanodomains being highly graphitic along c-axis and very graphenic along ab plane directions, where the nanodomains are randomly packed to form micron-sized particles, thus forming a polynanocrystalline structure. The polynanocrystalline graphite is very unique, structurally different from low-dimensional nanocrystalline carbon materials, e.g., fullerenes, carbon nanotubes, and graphene, nanoporous carbon, amorphous carbon and graphite, where it has a relatively low specific surface area of 91 m2/g as well as a low Archimedes density of 0.92 g/cm3. The structure is essentially hollow to a certain extent with randomly arranged nanosized graphite building blocks. This novel structure with disorder at nanometric scales but strict order at atomic scales enables substantially superior long-term cycling life for K-ion storage as an anode, where it exhibits 50% capacity retention over 240 cycles, whereas for graphite, it is only 6% retention over 140 cycles.

Lesel B.K., Ko J.S., Dunn B., Tolbert S.H.

Charge storage devices with high energy density and enhanced rate capabilities are highly sought after in today's mobile world. Although several high-rate pseudocapacitive anode materials have been reported, cathode materials operating in a high potential range versus lithium metal are much less common. Here, we present a nanostructured version of the well-known cathode material, LiMn2O4. The reduction in lithium-ion diffusion lengths and improvement in rate capabilities is realized through a combination of nanocrystallinity and the formation of a 3-D porous framework. Materials were fabricated from nanoporous Mn3O4 films made by block copolymer templating of preformed nanocrystals. The nanoporous Mn3O4 was then converted via solid-state reaction with LiOH to nanoporous LixMn2O4 (1 < x < 2). The resulting films had a wall thickness of ∼15 nm, which is small enough to be impacted by inactive surface sites. As a consequence, capacity was reduced by about half compared to bulk LiMn2O4, but both charge and discharge kinetics as well as cycling stability were improved significantly. Kinetic analysis of the redox reactions was used to verify the pseudocapacitive mechanisms of charge storage and establish the feasibility of using nanoporous LixMn2O4 as a cathode in lithium-ion devices based on pseudocapacitive charge storage.

Ju Z., Zhang S., Xing Z., Zhuang Q., Qiang Y., Qian Y.

Heteroatom-doped graphene is considered a potential electrode materials for lithium-ion batteries (LIBs). However, potassium-ion batteries (PIBs) systems are possible alternatives due to the comparatively higher abundance. Here, a practical solid-state method is described for the preparation of few-layer F-doped graphene foam (FFGF) with thickness of about 4 nm and high surface area (874 m(2)g(-1)). As anode material for LIBs, FFGF exhibits 800 mAh·g(-1) after 50 cycles at a current density of 100 mA·g(-1) and 555 mAh·g(-1) after 100 cycles at 200 mA·g(-1) as well as remarkable rate capability. FFGF also shows 165.9 mAh·g(-1) at 500 mA·g(-1) for 200 cycles for PIBs. Research suggests that the multiple synergistic effects of the F-modification, high surface area, and mesoporous membrane structures endow the ions and electrons throughout the electrode matrix with fast transportation as well as offering sufficient active sites for lithium and potassium storage, resulting in excellent electrochemical performance. Furthermore, the insights obtained will be of benefit to the design of reasonable electrode materials for alkali metal ion batteries.

Tang J., Salunkhe R.R., Zhang H., Malgras V., Ahamad T., Alshehri S.M., Kobayashi N., Tominaka S., Ide Y., Kim J.H., Yamauchi Y.

Single metal-organic frameworks (MOFs), constructed from the coordination between one-fold metal ions and organic linkers, show limited functionalities when used as precursors for nanoporous carbon materials. Herein, we propose to merge the advantages of zinc and cobalt metals ions into one single MOF crystal (i.e., bimetallic MOFs). The organic linkers that coordinate with cobalt ions tend to yield graphitic carbons after carbonization, unlike those bridging with zinc ions, due to the controlled catalytic graphitization by the cobalt nanoparticles. In this work, we demonstrate a feasible method to achieve nanoporous carbon materials with tailored properties, including specific surface area, pore size distribution, degree of graphitization and content of heteroatoms. The bimetallic-MOF-derived nanoporous carbon are systematically characterized, highlighting the importance of precisely controlling the properties of the carbon materials. This can be done by finely tuning the components in the bimetallic MOF precursors and thus designing optimal carbon materials for specific applications.

Zhang C., Huang M., Li T., Maisuradze M., Li Q., Meng Q., Xiao B., Wei F., Sui Y., Yang W., Qi J., Giorgetti M., Shao R.

Yang G., Yang Y., Li Y., Song F., Chen Q.

Liu Y., Dai S., Deng J., Jiang D., Jia X., Meng Q., Wang H., Liu L.

Li H., Yan Q., Li J., Qiu J., Zhang H.

AbstractPorous carbon materials (PCMs) have long played key roles in energy storage and conversion fields, known for their abundant raw materials, tunable pore structures, large surface area, and excellent conductivity. Despite significant progress, there remains a substantial gap between the precise design of PCMs and the full utilization of their unique properties for developing high‐performance electrode materials. Herein, this review systematically and comprehensively introduces PCMs from traditional synthesis, machine learning‐assisted design principles to their energy storage and conversion applications. Specifically, the preparation methods for microporous, mesoporous, macroporous, and hierarchically porous carbon materials are thoroughly summarized, with an emphasis on structural control rules and formation mechanisms. It also highlights the unique advantages of PCMs in alkali metal‐ion batteries, metal–sulfur batteries, supercapacitors, and electrocatalysis. Insights from in situ and operando characterizations provide a deep understanding of the correlation between structure and performance. Finally, current challenges and future directions are discussed, emphasizing the need for further advancements to meet evolving energy storage and conversion demands. This review offers valuable guidance for the rational design of high‐performance porous carbon electrode materials, and points out key research directions for future development.

Kim H., Na J., Park S.

K–Se batteries offer high energy density and cost-effectiveness, making them promising candidates for energy storage systems. However, their practical applications are hindered by Se aggregation, sluggish ion diffusion, and significant volumetric expansion. To address these challenges, monodisperse hierarchical N-doped carbon microspheres (NCHS) with uniformly sized pores were synthesized as cathode hosts. The flower-like microstructure, formed by the assembly of two-dimensional building blocks, mitigated Se aggregation and facilitated uniform distribution within the pores, enhancing Se utilization. Nitrogen doping, introduced during synthesis, strengthened chemical bonding between selenium and the carbon host, suppressed side reactions, and accelerated reaction kinetics. These synergistic effects enabled efficient ion transport, improved electrolyte accessibility, and enhanced redox reactions. Additionally, the uniform particle and pore sizes of NCHS effectively mitigated volumetric expansion and surface accumulation, ensuring long-term cycling stability and superior electrochemical performance. Se-loaded NCHS (Se@NCHS) exhibited a high discharge capacity of 199.4 mA h g−1 at 0.5 C after 500 cycles with 70.4% capacity retention and achieved 188 mA h g−1 at 3.0 C, outperforming conventional carbon hosts such as Super P. This study highlights the significance of structural and chemical modifications in optimizing cathode materials and offers valuable insights for developing high-performance energy storage systems.

Lin X., Jia L., Lu X., Tan X., Li H., Chen S., Yang C., Wang Y., Mai W., Wu Y., Luo Y.

Abstract Spinel LiMn2O4 (LMO) is deemed to be a promising cathode material for commercial lithium-ion batteries (LIBs) in prospect of its cost-effectiveness, nontoxicity, fabulous rate capability, and high energy density. Nevertheless, the LMO is inevitably confronted with sluggish diffusion kinetics and drastic capacity degradation triggered by multiple issues, including Jahn–Teller distortion, Mn dissolution, and structural attenuation. Thereinto, a metal-organic framework (MOF) chemistry engineering for hierarchical micro-/nano-structural F, O-dual-doped carbon embedded oxygen vacancy enriched LiMn2O4 cathode (OV-LMO@FOC) is proposed for longevous LIBs. Bestowed by experimental and theoretical implementations, systematic investigations of OV-LMO@FOC endow that the meticulous integration of F, O-dual-doped carbon and oxygen vacancy in LMO-based cathode reconfigures the electronic structure, boosts electronic conductivity, expedites diffusion capability, facilitates energetically preferable Li+ adsorption, and suppresses Mn dissolution in the electrolyte, consequently achieving fabulous long-term cycling stability. As expected, the OV-LMO@FOC behaves with compelling electrochemical performance with prosperous reversible capacity (130.2 mAh g−1 at 0.2 C upon 200 cycles), exceptional rate capacity (93.7 mAh g−1 even at 20 C), and pronounced long-term cyclability (112.5 mAh g−1 after 1200 cycles with 77.6% capacity retention at 1 C). Even at the ultrahigh current density of 5 C, the OV-LMO@FOC bears a brilliant capacity of 96.9 mAh g−1 upon 1000 cycles with an extraordinary capacity retention of 90.7%, and maintains a discharge capacity of 70.9 mAh g−1 upon 4000 cycles. This work envisions the MOF-chemistry in surface modification and electronic modulation engineering of high-performance cathode materials towards industrialization in automotive market.

Sun Z., Liu H., Li W., Zhang N., Zhu S., Chen B., He F., Zhao N., He C.

Xiong S., Liu S., Sun K., Wu Q., Gao Y., Zhou Y., Hou L., Gao F.

Pan Q., Li B., Liu S., Yang Y., Tang X., Liu H., Huang R., Wang J.

Liu Y., Liu P., Cai Y., Zhu M., Dou N., Zhang L., Men Y., Pan Y.

AbstractWidely used catalysts for electrocatalytic hydrogen (H2) evolution reaction (HER) have high platinum (Pt) contents and show low efficiencies in neutral and alkaline solutions. Herein, a carbon nanotube (CNT) supported Pt catalyst (Pt/CNT45) with 1 wt.% Pt is fabricated. For HER, the mass activity of Pt/CNT45 in acidic (18.76 A mgPt−1), neutral (3.92 A mgPt−1), and alkaline (3.88 A mgPt−1) solutions is respectively much higher than those on commercial Pt/C catalyst with 20 wt.% Pt (acidic: 0.31 A mgPt−1, neutral: 0.03 A mgPt−1, alkaline: 0.07 A mgPt−1). Thus, Pt/CNT45 enhances HER not only in acidic solutions but also in neutral and alkaline solutions. Ptδ+ at Pt‐CNT interface on Pt/CNT45 promotes water (H2O) dissociation and hydroxyl (OH) desorption from Pt/CNT45, thus enhancing HER. This work opens a new way for enhancing HER in a wider pH range by catalyst with low Pt content, and helpful for commercialization.

Chai L., Li R., Sun Y., Zhou K., Pan J.

AbstractNew carbon‐based materials (CMs) are recommended as attractively active materials due to their diverse nanostructures and unique electron transport pathways, demonstrating great potential for highly efficient energy storage applications, electrocatalysis, and beyond. Among these newly reported CMs, metal–organic framework (MOF)‐derived CMs have achieved impressive development momentum based on their high specific surface areas, tunable porosity, and flexible structural‐functional integration. However, obstacles regarding the integrity of porous structures, the complexity of preparation processes, and the precise control of active components hinder the regulation of precise interface engineering in CMs. In this context, this review systematically summarizes the latest advances in tailored types, processing strategies, and energy‐related applications of MOF‐derived CMs and focuses on the structure‐activity relationship of metal‐free carbon, metal‐doped carbon, and metallide‐doped carbon. Particularly, the intrinsic correlation and evolutionary behavior between the synergistic interaction of micro/nanostructures and active species with electrochemical performances are emphasized. Finally, unique insights and perspectives on the latest relevant research are presented, and the future development prospects and challenges of MOF‐derived CMs are discussed, providing valuable guidance to boost high‐performance electrochemical electrodes for a broader range of application fields.

Piernas-Muñoz M.J., Zarrabeitia M.

Potassium-ion batteries (KIBs) have attracted significant attention in recent years as a result of the urgent necessity to develop sustainable, low-cost batteries based on non-critical raw materials that are competitive with market-available lithium-ion batteries. KIBs are excellent candidates, as they offer the possibility of providing high power and energy densities due to their faster K+ diffusion and very close reduction potential compared with Li+/Li. However, research on KIBs is still in its infancy, and hence, more investigation is required both at the materials level and at the device level. In this work, we focus on recent strategies to enhance the electrochemical properties of intercalation anode materials, i.e., carbon-, titanium-, and vanadium-based compounds. Hitherto, the most promising anode materials are those carbon-based, such as graphite, soft, or hard carbon, each with its advantages and disadvantages. Although a wide variety of strategies have been reported with excellent results, there is still a need to improve the standardization of the best carbon properties, electrode formulation, and electrolyte composition, given the impossibility of a direct comparison. Therefore, additional effort should be made to understand what are the crucial carbon parameters to develop a reference electrode and electrolyte formulation to further boost their performance and move a step forward in the commercialization of KIBs.

Liu M., Wu X., Jiang Z., Li W., Liu F., Zhang W., Zheng W.

Zheng G., Xing Z., Wang J., Lu M., Hong H., Ju Z.

Larbi L., Le Pham P.N., Larhrib B., Matei-Ghimbeu C., Monconduit L., Stievano L.