Anode Material For Potassium-ion Batteries Research Articles

Facile Synthesis of Hollow Carbon Nanospheres and Their Potential as Stable Anode Materials in Potassium-Ion Batteries.

Hollow carbon nanospheres (HCNs) have found broad applications in a large variety of application fields. Unfortunately, HCNs are known for their tedious operations and are incompetent for scalable synthesis for those widely adopted nanocasting-based routes. Here, we report a facile and highly efficient method for the creation of hollow carbon structures by tuning the growth kinetics of its polymeric precursor. We identified that a controlled polymerization of Cu2+-poly(m-phenylenediamine) (Cu-PmPD) could form nanospheres with modulated inner chemical inhomogeneity, where the core of the particles was low in polymerization degree and water soluble, whereas the outer part was water insoluble. Therefore, a simple water washing of the prepared polymeric particles directly formed hollow nanospheres with a good control on the structural features including their cavity size and shell thickness. HCNs were formed through a following heat treatment and were able to exhibit promising potential as a stable anode material when tested in potassium-ion batteries.

MoS2/N-doped graphene aerogles composite anode for high performance sodium/potassium ion batteries

Three-dimensional porous MoS2/nitrogen-doped graphene aerogels (MoS2/NGA) with different MoS2 loading masses were synthesized by a simple hydrothermal method. The unique structure can provide more Na+ (K+) transport channels and the three-dimensional porous morphology could greatly absorb the volume expansion of MoS2 during charging and discharging process. As the anode of sodium-ion batteries (SIBs), this material provides a specific capacity of 673 mAh g−1 at a current density of 100 mA g−1 with long cycle stability. In addition, the composite shows a specific capacity of 305 mAh g−1 at 2000 mA g−1 and exhibits excellent capacity reversibility after rate performance test, indicating that it is a promising anode choice for SIB. As the anode material of potassium-ion batteries (KIBs), it provides a reversible specific capacity of 349 mAh g−1 at a current density of 100 mA g−1. It has a specific capacity of 72 mAhg−1 at 5000 mAg−1 and exhibits excellent capacity reversibility after rate performance test as well. Therefore, this work provides some insights into the fabrication of MoS2/graphene composites and is helpful for the design of high-performance anode materials of metal ion batteries.

Research progress on carbon anode materials in potassium-ion batteries

Aprotic potassium-ion batteries (KIBs) have drawn much attention owing to their high energy density and low cost, and abundant potassium resources. The realization of electrochemical potassiation/depotassiation in commercial graphite is of great significance to the practical application of KIBs. However, some tough issues still exist, such as the huge volume expansion of the graphite anodes, the fast decay of capacity and the poor rate performance. Researchers have tried to improve the electrochemical performance of KIBs by developing other anode candidate materials, including various carbon materials, metal oxides, and transition metal compounds. To date, the majority of studies have focused on carbon materials because of their relatively simple preparation, low cost, and environmental safety. In this review, the latest research progress on carbon anode materials for KIBs is systematically summarized. The synthesis methods and the storage mechanism of the carbon anodes with excellent electrochemical performance are summarized. Research prospects for KIBs are also proposed.

Recent Research Progress of Anode Materials for Potassium‐ion Batteries

The next‐generation smart grid for the storage and delivery of renewable energy urgently needs to develop a low‐cost and rechargeable energy storage technology beyond lithium‐ion batteries (LIBs). Owing to the abundance of potassium (K) resources and the similar electrochemical performance to that of LIBs, potassium‐ion batteries (PIBs) have been attracted considerable interest in recent years, and significant progress has been achieved concerning the discovery of high‐performance electrode materials for PIBs. This review especially summarizes the latest research progress regarding anode materials for PIBs, including carbon materials, organic materials, alloys, metal‐based compounds, and other new types of compounds. The reversible K‐ion storage principle and the electrochemical performance (i.e., capacity, potential, rate capability, and cyclability) of these developed anode materials are summarized. Furthermore, the challenges and the corresponding effective strategies to enhance the battery performance of the anode materials are highlighted. Finally, prospects of the future development of high‐performance anode materials for PIBs are discussed.

Facilely self-assembled MnS/S-doped reduced graphene oxide network with enhanced performance for potassium-ion battery

A MnS nanoparticles/S-doped reduced graphene oxide (MnS/S-rGO) network is prepared via a facile selfassembly method, and then the MnS-based anode material of potassium-ion batteries is investigated for the first time. The two-pronged strategy that the construction of a perforative 3D graphene skeleton and the robust MnS-enclosed configuration by the graphene wrinkles result in favorable structural stability and fast e-/K+ transfer kinetics. The MnS/S-rGO electrode exhibits stable reversible capacity of 215 mAh g−1 after 70 cycles and high rate capacity retention of 41.6% at 1 A g−1. In addition, the ex-situ XRD analysis verifies the high reversibility of the electrochemical redox reactions of MnS, demonstrating the featured bifunctional structure design is rational toward high-quality K+ storage.

Decoration of hollow nitrogen-doped carbon nanofibers with tapered rod-shaped NiCo2S4 as a 3D structural high-rate and long-lifespan self-supported anode material for potassium-ion batteries

Although potassium ion batteries (KIBs) have been invested in development as an emerging low-cost, high-content energy storage system at present. However, the large ionic radius of K+-ion lead to poor rate performance and low cycle life. Therefore, it is extremely necessary to develop a new type of potassium storage material. Here, we report a novel three-dimensional (3D) structural self-supported anode composite material for KIBs, which consists of tapered rod-shaped nanomaterial NiCo2S4 and nitrogen-doped hollow carbon nanofibers (NiCo2S4@N-HCNFs). Then, the composite material was obtained by high temperature carbonization and hydrothermal reaction process. The prepared electrode materials were used to assemble K half-cells for electrochemical performance measurement, achieved the capacity of 263.7 mAh g−1 after 200 cycles at a current density of 100 mA g−1 and an outstanding stability of retaining 134.3 mAh g−1 at 3200 mA g−1 after 600 cycles. It has superior performance and convenient synthesis process over other reported metal sulfides self-supported anode materials for KIBs so far. The novel structure not only shorten the ion transmission distance, but also increase the contact area with the electrolyte. It can improve electrochemical performance effectively.

N-Doped carbon coated bismuth nanorods with a hollow structure as an anode for superior-performance potassium-ion batteries.

Bismuth (Bi) is a promising anode material for potassium-ion batteries due to its high energy density. However, the large volume change limits its applications. Herein, N-doped carbon coated Bi nanorods with a hollow structure are fabricated and they exhibit excellent long-term cycling performance (88% capacity retention over 1000 cycles) and high-rate ability (297 mA h g-1 at 20C, 94% capacity of that at 1C). Furthermore, the mechanism was expounded by in situ XRD, indicating a multi-phase reaction for the initial discharge process and three two-phase reactions for the subsequent charge/discharge processes.

Three-dimensional nitrogen-sulfur codoped layered porous carbon nanosheets with sulfur-regulated nitrogen content as a high-performance anode material for potassium-ion batteries.

Three-dimensional nitrogen-sulfur codoped layered porous carbon nanosheets (3D-NSCNs) with sulfur-regulated nitrogen content are constructed as a high-performance anode material for potassium-ion batteries (KIBs) through a gel and nitrogen-sulfur codoping process. Compared with the sample without sulfur doping, the 3D-NSCNs reveal enhanced electrical conductivity, specific surface area, and pyrrolic (N-5) and pyridinic (N-6) nitrogen contents, all of which are beneficial for increased electrochemical performances. After 200 cycles at a current density of 100 mA g-1, the 3D-NSCNs anode exhibits a specific capacity of 254.9 mA h g-1. After 2900 cycles at a higher charge-discharge current density of 1 A g-1, the specific capacity is still 171.1 mA g-1, and the capacity retention is 78.9%, indicating the application potential of the as-synthesized 3D-NSCNs as an anode material for KIBs. Domination by a surface-driven mechanism is proposed to explain the excellent rate and cycle performances and can also be validated by galvanostatic intermittent titration results, which show that the K+ diffusion coefficient in the 3D-NSCNs is improved after nitrogen-sulfur doping. This work demonstrates a new strategy to improve the electrochemical properties of carbon-based K-storage materials by increasing the N-5 and N-6 contents through sulfur doping while also producing micropores to increase the number of active sites.

K2 Ti2 O5 @C Microspheres with Enhanced K+ Intercalation Pseudocapacitance Ensuring Fast Potassium Storage and Long-Term Cycling Stability.

Benefiting from the natural abundance and low standard redox potential of potassium, potassium-ion batteries (PIBs) are regarded as one of the most promising alternatives to lithium-ion batteries for low-cost energy storage. However, most PIB electrode materials suffer from sluggish thermodynamic kinetics and dramatic volume expansion during K+ (de)intercalation. Herein, it is reported on carbon-coated K2 Ti2 O5 microspheres (S-KTO@C) synthesized through a facile spray drying method. Taking advantage of both the porous microstructure and carbon coating, S-KTO@C shows excellent rate capability and cycling stability as an anode material for PIBs. Furthermore, the intimate integration of carbon coating through chemical vapor deposition technology significantly enhances the K+ intercalation pseudocapacitive behavior. As a proof of concept, a potassium-ion hybrid capacitor is constructed with the S-KTO@C (battery-type anode material) and the activated carbon (capacitor-type cathode material). The assembled device shows a high energy density, high power density, and excellent capacity retention. This work can pave the way for the development of high-performance potassium-based energy storage devices.

Heteroatom-doped carbon inlaid with Sb2X3 (X = S, Se) nanodots for high-performance potassium-ion batteries

Antimony-based materials with high theoretical capacity have been considered as a promising anode materials for potassium-ion batteries (PIBs). Unfortunately, the large volume expansion leads to rapid capacity fading and poor rate capability. In this work, Sb2S3 (Sb2Se3) nanodots/carbon composites are constructed through pyrolysis and co-sulfurization (selenylation) process of sodium stibogluconate for the first time. In the composite, Sb2S3 (Sb2Se3) nanodots with diameters of 15–25 nm are uniformly inlaid into S(Se)-doped carbon skeleton. Notably the ultrafine nanodots can remarkedly shorten the ions diffusion distance with enhanced kinetic process. Also the S(Se)-doped carbon would provide the stable structure support and conductive path. When applied as the anode for PIBs, they all show satisfactory potassium-storage properties in terms of high reversible capacity and superior rate capability, especially the excellent electrochemical performances of Sb2Se3 nanodots/carbon with a reversible capacity of 312.03 mAh g−1 at 1000 mA g−1 after 200 cycles, which can be attributed to the synergistic effect of nanodots and doped carbon, minimizing potassiation-induced deformations and facilitating the reversible adsorption of K ions. More importantly, the volume changes during the K+ intercalation/deintercalation process have been analyzed in details, which is well consistent with the result of electrochemical performance, as expected.

Synthesis of the electrochemically stable sulfur-doped bamboo charcoal as the anode material of potassium-ion batteries

As an emerging energy storage technology, potassium-ion batteries (KIBs) are suitable for large-scale energy storage applications due to their abundant resources and low cost, but the known anode materials generally exhibit poor electrochemical performance. In this paper, synthesis of sulfur-doped bamboo charcoal (S-BC) anode materials are carried out to match the intercalation/deintercalation cycles of K+ by using biomass bamboo as a precursor and sulfur as a modifying element. Benefiting from the unique structure and composition formed during the activation, carbonization, and subsequently vulcanization at 700 °C, the S-BC materials exhibit stabilized electrochemical performance. The optimized S-BC-1 anode delivers a high specific capacity of 339.3 mAh g−1 at 50 mA g−1, a rate capacity of 124.2 mAh g−1 at 1 A g−1, and a cycling retention of 203.8 mAh g−1 at 200 mA g−1 after 300 cycles. It is indicated that the residual oxygen atoms and the doping sulfur in the BS can provide more active sites and increase the conductivity. The sustainable bamboo is demonstrated to be an environmentally friendly precursor to synthesize the high-performance anode material of KIBs. And it also provides a strategy to stabilize carbon-based anode materials by regulating their structure and composition in the synthetic process.

N-doped hollow carbon nanofibers anchored hierarchical FeP nanosheets as high-performance anode for potassium-ion batteries

Potassium-ion batteries (PIBs) are emerging as appealing technologies for energy storage applications due to the highly abundant potassium resource in nature and low cost of potassium. Iron phosphide (FeP) have been widely investigated as anode materials for PIBs, owing to its high theoretical specific capacity and the plentiful of its primitive materials (P and Fe). However, the practical application of FeP materials in PIBs suffers from serious capacity fading due to the large volume expansion caused by the intercalation/deintercalation of potassium ions. Here, hierarchical FeP nanosheets internally wired by N-doped hollow carbon nanofibers (N–CNF@FeP) is rationally designed and synthesized via a combination of hydrothermal route and phosphidation treatment. In such a unique nanoarchitecture, hierarchical FeP nanosheets are homogeneously anchored on the hollow carbon nanofibers with nitrogen-rich and porous properties. This unique designed structure not only improve the electronic conductivity and structural stability of the hybrid composite but also facilitates the transport of electrons and K-ions. When applied as potassium ion battery, N–CNF@FeP composite manifests remarkably reversible capacities, ultra-long cycle life, as well as superior rate performances for potassium storage process. Moreover, at a current density of 0.1 A g−1, N–CNF@FeP composite delivers a high capacity of 210 mAh g−1 after 1000 cycles.

Boosting potassium storage in nanosheet assembled MoSe2 hollow sphere through surface decoration of MoO2 nanoparticles

Considering the suitable redox potential, low price, and abundant resource of potassium, potassium-ion batteries (PIBs) have attracted considerable attention as one of the alternatives to lithium-ion batteries (LIBs), however, the larger ionic radius of potassium ions makes it difficult to select suitable electrode materials. Herein, the MoSe2@MoO2 heterojunction in which MoO2 nanoparticles embedded on MoSe2 nanosheets was synthesized by hydrothermal method and used as a novel anode material for PIBs. The electrochemical performance of the heterojunction was greatly improved as compared with the pure MoSe2 and pure MoO2. At the current density of 500 mA g−1 after 100 cycle, the heterojunction electrode still maintains a capacity of 255 mA h g−1 and the coulomb efficiency is close to 100%. By introducing metallic MoO2 can improve the electrical conductivity, furthermore, the MoSe2@MoO2 heterostructures facilitate interfacial electron transport and built-in electric field makes the diffusion of K-ion easier. In addition, the well dispersed MoO2 nanoparticles prevent the restacking of MoSe2 nanosheets and maintain the structure stability during the charge/discharge process.

Potassium‐Ion Batteries: Encapsulating Carbon‐Coated MoS2 Nanosheets within a Nitrogen‐Doped Graphene Network for High‐Performance Potassium‐Ion Storage (Adv. Mater. Interfaces 22/2019)

In article number 1901066, Jingyuan Zhang, Shi Tao, Wangsheng Chu, and co-workers design a dual carbon encapsulated nanostructure of MoS2/[email protected] hybrids as anode materials for potassium-ion batteries, which exhibit superior rate performance and long cycling stability. The potassium-storage mechanism study reveals that the highly reversibly during the charge/discharge process with K+ intercalation and conversion reaction.

Cotton-derived oxygen/sulfur co-doped hard carbon as advanced anode material for potassium-ion batteries

Hard carbon is regarded as promising anode materials for potassium-ion batteries (KIBs) owing to their low price and easy availability. However, the limited rate capability still needs to be improved. Herein, we demonstrate the fabrication of oxygen/sulfur co-doped hard carbon through a facile hydrolyzation-sulfuration process of skimmed cotton. The simultaneous dopants significantly improve potassium ion diffusion rate. When served as the anode for KIBs, this hydrolyzed hard carbon delivered a high reversible capacity (409 mAh/g at 0.1 A/g), superior rate capability (135 mAh/g at 2 A/g) and excellent cyclability (about 120 mAh/g overt 500 cycles at 2 A/g). This work provides a facile strategy to prepare low-cost doped-hard carbon with superior potassium storage property.

Ultrafine SnO2 nanoparticles encapsulated in 3D porous carbon as a high-performance anode material for potassium-ion batteries

A novel nanocomposite of ultrafine SnO2 nanoparticles encapsulated in 3D porous carbon is prepared by freeze-drying followed with sintering and dealloying strategy. The SnO2 nanoparticles are obtained by selective etching of Cu from Cu6Sn5 nanoparticles. The ultrafine oxide nanoparticles together with 3D porous carbon network are highly effective in accommodating the huge volume change of SnO2 during potassiation and depotassiation processes. As a result, the obtained sample presents excellent potassium-ion storage performance including high reversible capacity (270.3 mAh g−1 at 100 mA g−1 after 200 cycles and capacity retention close to 80%), ultralong cycle lifespan and excellent rate performance (144.6 mAh g−1 at 2 A g−1).

Facile Synthesis of Copper Sulfide Nanosheet@Graphene Oxide for the Anode of Potassium‐Ion Batteries

Potassium‐ion batteries (PIBs) are promising to expedite future energy storage progress because of the low price and high energy density of potassium. Copper sulfide (CuS), a plentiful, low‐priced, and nontoxic transition metal sulfide, is going to be a promising anode material with high capacity and excellent rate performance for energy storage. Herein, thioacetamide is chosen as the sulfur source to prepare CuS nanosheets uniformly anchored on graphene oxide (CuS@GO) using a simple one‐step method. The prepared CuS@GO increases the active sites and GO effectively alleviates the polymerization of CuS during the cycling. When CuS@GO is utilized as an anode material for PIBs, it exhibits a preeminent specific capacity of 410 mAh g−1 (at a current density of 100 mA g−1) and outstanding rate capability (even achieving a higher capacity of 196.5 mAh g−1 at a current density of 1000 mA g−1). In this study, the phase evolution of CuS during the potassium‐ion insertion and extraction process is further explored by in situ X‐ray diffraction studies, which is significant to clearly understand the energy storage mechanism of CuS. A novel perspective in potassium storage mechanism for transition metal sulfides is provided.

Two-Dimensional T-NiSe2 as a Promising Anode Material for Potassium-Ion Batteries with Low Average Voltage, High Ionic Conductivity, and Superior Carrier Mobility.

Potassium-ion batteries (KIBs) have attracted great attention due to their unique advantages including abundant resources, low redox potential of K, and feasible usage of cheap aluminum current collector in battery assembly. In the present work, through first-principles calculations, we find that the recently synthesized two-dimensional T-NiSe2 is a promising anode material of KIBs. It possesses a large capacity (247 mAh/g), small diffusion barrier (0.05 eV), and low average voltage (0.49 V), rendering T-NiSe2 a high-performance KIB anode candidate. In addition, we analyze the carrier mobility of T-NiSe2, and the results demonstrate that it possesses a superior carrier mobility of 1685 cm2/(V s), showing the potential for applications in nanoelectronic devices.

Metal–organic-frameworks-engaged formation of Co0.85Se@C nanoboxes embedded in carbon nanofibers film for enhanced potassium-ion storage

Potassium-ion batteries (PIBs) are considered as viable energy storage system due to the abundance and low cost of potassium. However, their development is still hampered by the lack of suitable electrode materials that can withstand the structural deterioration caused during intercalation/deintercalation of large potassium ions. Herein, a flexible and freestanding anode material consisting of Co0.85Se@carbon nanoboxes (Co0.85Se@C) embedded in carbon nanofibers films is fabricated through a metal‒organic-framework-engaged electrospinning strategy coupled to a one-step confined carbonization-selenidation process. The rationally designed electrode with high mass loading of active material offers attractive structural features, particularly Co0.85Se@C nanoboxes with large surface area and requisite void space to accommodate the large volumetric expansion for boosted cycling stability. Moreover, the robust conductive carbon nanofiber network not only improves the electronic conductivity, but also stabilizes the integral structure upon repeated K+ insertion/deinsertion. As a result, this unique nanoarchitecture demonstrates excellent cycling stability as an anode material for PIBs, with a high reversible capacity of 299 mA h g−1 at 1 A g−1 after 400 cycles and achieves remarkable rate performance with a specific capacity of 166 mA h g−1 at 5 A g−1. Most importantly, it is demonstrated that increasing the areal loading of active material in the electrode through a layer-by-layer stacking configuration further improves the energy density of the battery.

Synthesis of Mesoporous Carbon Using Waste Orange Peel As an Anode Material for Potassium-Ion Batteries with Long Cyclability

Potassium‐ion batteries (PIBs) have been considered as the most promising candidate due to their low cost and high safety to replace the Li-ion batteries. However, current graphite anode cannot encounter the demands for high storage capacity and low cost, which are required for the commercial PIBs. Thus, it is needed to discover porous carbon anode material with high capacity, longer cycle life, low cost, and environment friendless for PIBs. Porous carbon is regarded as an attractive anode material for PIBs due to its high conductivity, chemical stability, and expanded interlayer spacing, which can helpful to accommodate more K-ions. In particular, biomass derived porous carbon has the advantages as a renewable and low cost carbon source. It can also provide excellent 3-D porous nanostructure for high storage capacity and long cyclability in batteries. Among the biomass wastes, 15.6 million tons of orange peel is discarded every year. It may be very useful if we can use these wastes as a resource for an electrode of batteries. Orange peel is mainly composed of cellulose, hemicellulose, lignin, and pectin, which are known as excellent carbon precursors. In this study, we fabricated mesoporous carbon from orange peel through a facile one step carbonization approach without introducing extra activation agents. The mesoporous carbon displayed the first discharge and charge capacities of 408 and 224 mAh g-1, respectively, corresponding to a Coulombic efficiency of 55%. Even after 100 cycles, the electrode maintained a high capacity 210 mA g-1. When the specific current is further increased to 200 mA g-1, the high specific capacity of 150 mA g-1 was still achieved, which corresponds to a capacity retention of 80% after 2000 cycles. This superior cycling stability is attributed to the improved ionic diffusion kinetics and electronic conductivity resulting from the mesoporous structure and large interlayer spacing. Furthermore, a full cell composed of mesoporous carbon anode and potassium Prussian blue cathode displayed an adequate electrochemical performance.