Anode For Potassium-ion Batteries Research Articles

Recent Advances and Challenges in Ti-Based Oxide Anodes for Superior Potassium Storage.

Developing high-performance anodes is one of the most effective ways to improve the energy storage performances of potassium-ion batteries (PIBs). Among them, Ti-based oxides, including TiO2, K2Ti6O13, K2Ti4O9, K2Ti8O17, Li4Ti5O12, etc., as the intrinsic structural advantages, are of great interest for applications in PIBs. Despite numerous merits of Ti-based oxide anodes, such as fantastic chemical and thermal stability, a rich reserve of raw materials, non-toxic and environmentally friendly properties, etc., their poor electrical conductivity limits the energy storage applications in PIBs, which is the key challenge for these anodes. Although various modification projects are effectively used to improve their energy storage performances, there are still some related issues and problems that need to be addressed and solved. This review provides a comprehensive summary on the latest research progress of Ti-based oxide anodes for the application in PIBs. Besides the major impactful work and various performance improvement strategies, such as structural regulation, carbon modification, element doping, etc., some promising research directions, including effects of electrolytes and binders, MXene-derived TiO2-based anodes and application as a modifier, are outlined in this review. In addition, noteworthy research perspectives and future development challenges for Ti-based oxide anodes in PIBs are also proposed.

Ultrastable Graphite-Potassium Anode through Binder Chemistry.

Graphite with abundant reserves has attracted enormous research interest as an anode of potassium-ion batteries (PIBs) owing to its high plateau capacity of 279 mAh g-1 at ≈0.2V in conventional carbonate electrolytes. Unfortunately, it suffers from fast capacity decay during K+ storage. Herein, an ultrastable graphite-potassium anode is developed through binder chemistry. Polyvinyl alcohol (PVA) is utilized as a water-soluble binder to generate a uniform and robust KF-rich SEI film on the graphite surface, which can not only inhibit the electrolyte decomposition, but also withstand large volume expansion during K+ -insertion. Compared to the PVDF as binder, PVA-based graphite anode can operate for over 2000 cycles (running time of 406 days at C/3) with 97% capacity retention in KPF6 -based electrolytes. The initial Coulombic efficiency (ICE) of graphite anode is as high as 81.6% using PVA as the binder, higher than that of PVDF (40.1%). Benefiting from the strong adhesion ability of PVA, a graphite||fluorophosphate K-ion full battery is further built through 3D printing, which achieves a record-high areal energy of 8.9 mWh cm-2 at a total mass loading of 38mg cm-2 . These results demonstrate the important role of binder in developing high-performance PIBs.

Construction of mesoporous N-doped carbon-coated MXene-MoS2 heterostructured microspheres via a spray-drying method as a high capacity and long cycle-life anode for potassium-ion batteries

Heterostructured materials with 2D architecture capitalizing on the unique benefits of each component and the emergent properties from their synergy have ignited considerable interest in the field of rechargeable batteries. Nevertheless, inhibiting the restacking issue inherent to 2D materials and optimizing the structural design to enhance the electrochemical reactions continue to pose substantial challenges. In this study, we successfully fabricated porous 3D N-doped carbon microspheres consisting of MXene and molybdenum disulfide (MX/MoS2 @NC) for use as an electrode material in potassium-ion batteries via a facile spray-drying method. The MX/MoS2 @NC electrode showcased excellent electrochemical properties as an anode, delivering stable cycling performance and minimal capacity decay (350 mA h g−1 at 0.5 A g−1 after 400 cycles). It also exhibits improved rate capability and enhanced ion transport kinetics (219 mA h g−1 at 2.0 A g−1). The high performance of this composite can be traced back to its 3D microspherical structure facilitating efficient ion transport, the synergy between MXene and N-doped carbon enhancing its structural robustness and electrical conductivity, and the 2D MXene nanosheets preventing MoS2 restacking. This investigation underscores the MX/MoS2 @NC composite as a promising candidate for potassium-ion battery applications.

Enhancing potassium ions adsorption on mesoporous carbon spheres with abundant internal surface via engineering sulfur doping sites towards superior rate capability

Mesoporous carbon spheres (MCSs) show great potential for using as high-performance anodes in potassium-ion batteries (PIBs). Design and synthesis of MCSs with suitable multiscale structures and heteroatom doping or co-doping in MCSs are successfully employed to optimize the ion and electron transportation, however, it is still a challenge to explore MCS-based anodes with satisfactory potassium storage performance. In this work, we report novel S-doped MCS samples with abundant internal surfaces for potassium storage. The S doping sites are controlled during the synthesis, and the effect of different doping sites on the potassium storage is systematically studied. It is found that S doping between the carbon layers enlarges interlayer spacing and facilitates potassium ion adsorption. Consequently, the optimized sample shows an excellent rate capability of 144 mAh/g at 5.0 A/g, and a high reversible specific capacity of 325 mAh/g after 100 cycles at 0.1 A/g with a capacity retention of 91.2%. The important role of element doping sites on ion adsorption and ion storage performance is confirmed by theoretical investigations. Controlling the doping sites in MCSs provides a new approach to designing high-performance electrodes for energy storage and conversion applications.

Bamboo-like tubular nitrogen-doped carbon derived from g-C3N4 as an ultra-high performance anode of potassium-ion battery

Carbon materials are still the most widely studied anode materials for potassium ion batteries (PIBs) attributed to their advantages of wide source, controllability, and environmental friendliness. In this paper, a bamboo-like tubular nitrogen-doped carbon material (CNC) was prepared by using g-C3N4 as the precursor and transition metal salt as the catalyst and template. CNC has the advantages of a bamboo-like tubular structure, rich nitrogen content, and large layer spacing. As anode of PIBs, CNC can deliver an impressive initial reversible capacity of 488.6 mAh/g at 0.1 A/g. At a high current density of 1 A/g, CNC still retains a reversible capacity of 291 mAh/g after 1000 cycles. The excellent performance of CNC anode can be due to the porous bamboo-like tubular structure that promotes K ions diffusion and the rich nitrogen content that provides abundant active sites for K ions.

Short-Range Graphitic Nanodomains in Hypocrystalline Carbon Nanotubes Realize Fast Potassium Ion Migration and Multidirection Stress Release.

Defect-rich carbon materials are considered as one of the most promising anodes for potassium-ion batteries due to their enormous adsorption sites of K+ , while the realization of both rate capability and cycling stability is still greatly limited by unstable electrochemical kinetics and inevitable structure degradation. Herein, an Fe3+ -induced hydrothermal-pyrolysis strategy is reported to construct well-tailored hybrid carbon nanotubes network architecture (PP-CNT), in which the short-range graphitic nanodomains are in-situ localized in the pea pod shape hypocrystalline carbon. The N,O codoped hypocrystalline carbon region contributes to abundant defect sites for potassium ion storage, ensuring high reversible capacity. Meanwhile, the short-range graphitic nanodomains with expanded interlayer spacing facilitate stable K+ migration and fast electron transfer. Furthermore, the finite element analysis confirms the volume expansion caused by K+ intercalation can be availably buffered due to the multidirection stress release effect of the unique porous pea pod shape, endowing carbon nanotubes with superior structural integrity. Consequently, the PP-CNT anode exhibits superior potassium-storage performance, including high reversible capacity, exceptional rate capability, and ultralong cycling stability. This work opens a new avenue for the fabrication of advanced carbon materials for achieving durable and fast potassium storage.

Antimony/Polypyrrole/CNTs composites with three-dimensional structure as highly stable anodes for potassium ion battery

Antimony (Sb)-based materials are attractive as anodes in potassium ion batteries (PIBs). However, poor cycling and volume expansion of the Sb-based anodes hinder their development in PIBs. In this work, we prepared a novel three-dimensional Sb nanoparticle/polypyrrole/carbon nanotube (Sb/PPy/CNT) hybrid anode material. The obtained Sb/PPy/CNT maintained a discharge capacity of 555.1 mAh g−1 after 200 cycles at a current density of 100 mA g−1, and 347.5 mAh g−1 after 600 cycles at a high current density of 1000 mA g−1, showing outstanding potassium storage capacity and cycling performance. This excellent performance was attributed to the array of electron transfer networks formed in the hydrogel network, as well as inhibition of the volume expansion exhibited by potassium ions during embedding/detachment of the CNTs and Sb nanoparticles arising from encapsulation by PPy films. This study provides a prerequisite for expanding the use of high-performance anode materials for PIBs.

Advancements and Prospects of Graphite Anode for Potassium-Ion Batteries.

Potassium-ion batteries (KIBs) have recently attracted considerable attention owing to their resource abundance, low cost and environmental friendliness. Graphite as a mature commercial anode material for lithium-ion batteries, has been proved as a promising anode candidate for KIBs by reversible forming potassium-graphite intercalation compounds. However, large volume expansion and sluggish K+ kinetics caused by the incompatibility between large radius of K+ and the small interlayer spacing of graphite, result in the poor cycle stability and rate performances, hindering its practical application. Extensive research efforts have focused on improving the potassium storage performance of graphite anodes. This review provides an overview of recent advances in addressing these challenges and optimizing the electrochemical performance of graphite anodes for KIBs. Various strategies to improve the electrochemical performance of graphite and graphitic carbon anodes, such as microcrystalline regulation, heteroatom doping, morphological adjustment, and coating modification, are discussed, while the critical issues and challenges associated with graphite anodes and the prospects for their advancement in KIBs are highlighted. The review offers valuable guidelines for rational structural design and promotes the commercial development of high-performance graphite anode materials for KIBs.

Utilization of PET derived hard carbon as a battery-type, higher plateau capacity anode for sodium-ion and potassium-ion batteries

Trash to Treasure is a less energy-intensive approach for upcycling plastic waste into value-added products to generate sustainable, cost-effective, eco-friendly materials. The carbonization of polyethylene terephthalate (PET) via a single-step process into hard carbon (HC) delivers a high-performing anode material for sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs). Direct pyrolysis of PET waste increases the interlayer spacing with partially closed slit-shaped micro and mesopores that significantly improves the lower potential plateau-based capacity to 68% of the total capacity, validating a battery-type anode material. The HC carbonized at 1000℃ delivers a reversible capacity of 337 mAh/g with capacity retention of 88% after 100 cycles at 30 mAh/g. The HC exhibits 80% capacity retention even after 1000 cycles at a 1C rate and is promising for fast cycling-high power density applications. In PIBs, the HC carbonized at 800℃ performs the best and shows a reversible capacity of 305 mAh/g, with a battery-type low voltage plateau contribution of 32%. The charge storage mechanism in SIBS and PIBs follows a three-stage storage mechanism, i.e., adsorption, intercalation, and pore-filling.

Tungsten chalcogenides as anodes for potassium-ion batteries

Tungsten chalcogenides as anodes for potassium-ion batteries

Ultrafine red phosphorus confined in reasonably designed pitch-based carbon matrix built of well-interconnected carbon nanosheets for high-performance lithium and potassium storage

Red phosphorus has been well-recognized as promising anode materials for lithium-ion batteries (LIBs) and potassium-ion batteries (PIBs) due to its extremely high theoretical capacity and low cost. However, the huge volume change and poor electric conductivity severely limit its further practical application. Herein, the nanoscale ultrafine red phosphorus has been successfully confined in a three-dimensional pitch-based porous carbon skeleton composed of well-interconnected carbon nanosheets through the vaporization-condensation method. Except for the traditional requirement of high electric conductivity and stable mechanical stability, the micropores and small mesopores in the porous carbon matrix centered at 1 to 3 nm and the abundant amount of oxygen-containing functional groups are also beneficial for the high loading and dispersion of red phosphorus. As anode for LIBs, the composite exhibits high reversible discharge capacities of 968 mAh g−1, excellent rate capabilities of 593 mAh g−1 at 2 A g−1, and long cycle performance of 557 mAh g−1 at 2 A g−1. More impressively, as the anode for PIBs, the composite presents a high reversible capacity of 661 mAh g−1 and a stable capacity of 312 mAh g−1 at 0.5 A g−1 for 500 cycles with a capacity retention up to 84.3%. This work not only sheds light on the structure design of carbon hosts with specific pore structure but also open an avenue for high value-added utilization of coal tar pitch.

Low-Cost Pitch Derived Lamellar N-Doped Carbon as a High-Performance Potassium-Ion Battery Anode

Low-Cost Pitch Derived Lamellar N-Doped Carbon as a High-Performance Potassium-Ion Battery Anode

Porous nitrogen-doped FeP/C nanofibers as promising anode for potassium-ion batteries

Porous nitrogen-doped FeP/C nanofibers as promising anode for potassium-ion batteries

The g-C3N4-derived nanoarchitectonics of nitrogen-doped carbon material as a high-rate performance anode for potassium ion batteries

Due to the advantages of abundant precursors, simple preparation, and environmental friendliness, nitrogen-doped carbon is considered one of the most potential anodes for potassium ion batteries (PIBs). Here, nitrogen-doped carbon materials (NC-2) were prepared by using secondary exfoliated g-C3N4 as a precursor, combined with sucrose, and subjected to hydrothermal and high-temperature pyrolysis. NC-2 is characterized by high nitrogen content, porous layered structure, and large interlayer spacing. NC-2 used as anode of PIBs shows a high reversible capacity of 261.07 mAh g−1 at 0.1 A g−1 and an impressive rate performance of 153.36 mAh g−1 at 2 A g−1. The impressive performance of NC-2 can be originated from the porous layered structure and enlarged interlayer spacing promotes the intercalation/deintercalation and the diffusion of K ions, and the defective carbon structure formed after nitrogen doping can supply abundant active sites for K ions. The results show that NC-2 has great potential in the field of PIBs anode.

Amorphous carbon with N-S bond active center for enhanced capacitive contribution of potassium-ion batteries

Carbon materials have great potential in achieving excellent potassium-ion batteries (PIBs), while the low theoretical capacity of carbon materials limits the application of potassium ion batteries. Here, we reported an amorphous porous carbon with rich N-S bonds (N-S/C) by simple self-assembly possess and pyrolysis possess. The prepared N-S/C material possesses plentiful N-S bonds, which can act as active center to enhance the electrochemical capacity and accelerate transport dynamics. In addition, abundant porous structure can increase the contact area between electrode materials and electrolyte to shortens the diffusion path of ion transport, thereby improving the rate performance. As PIBs anodes, the N-S/C material exhibits a markedly enhanced reversible capacity of 389 mAh g−1 at 50 mA g−1, excellent cycling stability (188.8 mAh g−1 at 500 mA g−1 after 1000 cycles) and rate performance (105 mAh g−1 at 2 A g−1). Importantly, the in-situ Raman unravels a reversible mechanism that intercalation/deintercalation of K+ into/from the N-S/C, and the electrochemical analysis shows the N-S bond can improve the capacitive activity and enable fast kinetics toward superior K+-storage. These results demonstrate a promising carbonaceous anode material for PIBs and may provide guidance for designing of electrode materials of PIBs.

Improved electrochemical performance of soft carbon derived from coal liquefaction residue coated with expanded graphite for Lithium/Potassium batteries

This study investigated the use of asphaltene from coal liquefaction residue (CLRA) as a precursor for creating carbon nanosheets, which were then used to create a unique sandwich structure of soft carbon (SC) coated with expanded graphite (EG) composite (SC@EG) anodes for both lithium-ion and potassium-ion batteries. The SC@EG was formed through a covalent bond between EG and SC, resulting in a porous structure with favorable porosity and copious defects that expedited the migration of both Li+ and K+ ions. The SC@EG showed good electrochemical properties including high reversible capacity (510 mAh/g at 0.5 A/g in LIBs and 268 mAh/g at 0.1 A/g in KIBs), good rate performance (172 mAh/g at 4 A/g in LIBs and 154 mAh/g at 1 A/g in KIBs) and cyclic stability, attributed to the exceptional electronic conductivity and profound porosity of the structure.

Ultrasound-assisted successive recovery of chemical activation agent and synthesis of high sulfur petroleum coke-based carbon anode with progressively improving performance K-ion storage

The effectiveness of continuous synthesis of petroleum coke-based potassium ion battery anodes by chemical activation agent cycle was systematically studied. The potassium ions storage performance in the synthesized carbon anode was measured. High‑sulfur petroleum coke, as a natural sulfur-doped hard carbon skeleton, can provide an excellent active site for the storage of potassium ions. Ultrasonic intensification significantly reduces the elution time required for neutralization and eliminates the need for a forced increase in elution temperature and rate to improve elution efficiency. In the continuous synthesis process, the recycled chemical activation agent not only does not destroy the activation effect but also has stable activation performance and a good driving force for the growth of activated carbon quality (the specific surface area is 1000 ∼ m2 g−1). Moreover, the sulfur content of the prepared hard carbon anode gradually decreases, whereas its electrical conductivity gradually increases, resulting in an increase in its potassium ions storage capacity. The carbon anode prepared by chemical activation agent after four cycles has a high reversible capacity of 290 mAh g−1 at 0.5 A g−1 and excellent cycling stability (99.5% hold rate at 0.5 A g−1 after 400 cycles). The galvanostatic intermittent titration technique results show that appropriate sulfur content and perfect carbon skeleton structure can promote potassium ions intercalation kinetics. In conclusion, the chemical activation agent cycling strategy can be used to achieve the continuous synthesis of petroleum coke-based potassium ion battery anode.

Bismuth Telluride Nanoplates Hierarchically Confined by Graphene and N-Doped C as Conversion-Alloying Anode Materials for Potassium-Ion Batteries.

Potassium-ion batteries (PIBs) have broad application prospects in the field of electric energy storage systems because of its abundant K reserves, and similar "rocking chair" operating principle as lithium-ion batteries (LIBs). Aiming to the large volume expansion and sluggish dynamic behavior of anode materials for storing large sized K-ion, bismuth telluride (Bi2 Te3 ) nanoplates hierarchically encapsulated by reduced graphene oxide (rGO), and nitrogen-doped carbon (NC) are constructed as anodes for PIBs. The resultant Bi2 Te3 @rGO@NC architecture features robust chemical bond of Bi─O─C, tightly physicochemical confinement effect, typical conductor property, and enhanced K-ion adsorption ability, thereby producing superior electrochemical kinetics and outstanding morphological and structural stability. It is visually elucidated via high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) that conversion-alloying dual-mechanism plays a significant role in K-ion storage, allowing 12 K-ion transport per formular unit employing Bi as redox site. Thus, the high first reversible specific capacity of 322.70mAhg-1 at 50mAg-1 , great rate capability and cyclic stability can be achieved for Bi2 Te3 @rGO@NC. This work lays the foundation for an in-depth understanding of conversion-alloying mechanism in potassium-ion storage.

Edge-nitrogen synergize with micropores to realize fast and durable potassium storage for carbon anode

Edge-N (pyridinic/pyrrolic-N) functionalized carbon is a promising anode for potassium-ion batteries, while micropores have been proven to be effective in increasing capacity and cyclability. However, the obtained carbon materials usually exhibit a low N-doping level and edge-N species based on the conventional pyrolysis method, and the exploration of the synergistic effect of edge-N doping and micropores on the potassium-storage performance is still lacking. Herein, a novel strategy is proposed to prepare edge-N doped carbon (ENC-850) by directly pyrolyzing supermolecule precursors self-assembled by terephthalic acid (BDC) and melamine (MA). Because the s-triazine structure in MA is more stable than BDC, which can easily ensure a higher N-doping content in carbon, and the decomposition of s-triazine structure is accompanied by the release of NCNH2 gas, which enables most doped N-atoms to be of edge-N configurations, favoring the adsorption storage of K-ions. Besides, the released small molecules can create numerous micropores, not only providing active sites, but accommodating volume fluctuation. Therefore, the optimized ENC-850 with the most suitable edge-N content of 60.6% (7.73 at% of total 11.71 at% N-doping) and micropores delivers a high capacity (280 mAh g−1 at 0.5 A g−1) and superior cycling stability (over 2000 cycles).

Organic-Inorganic Hybrid Interfaces Enable the Preparation of Nitrogen-Doped Hollow Carbon Nanospheres as High-Performance Anodes for Lithium and Potassium-Ion Batteries.

An abundant hollow nanostructure is crucial for fast Li+ and K+ diffusion paths and sufficient electrolyte penetration, which creates a highly conductive network for ionic and electronic transport. In this study, we successfully developed a molecular-bridge-linked, organic-inorganic hybrid interface that enables the preparation of in situ nitrogen-doped hollow carbon nanospheres. Moreover, the prepared HCNSs, with high nitrogen content of up to 10.4%, feature homogeneous and regular morphologies. The resulting HCNSs exhibit excellent lithium and potassium storage properties when used as electrode materials. Specifically, the HCNS-800 electrode demonstrates a stable reversible discharge capacity of 642 mA h g-1 at 1000 mA g-1 after 500 cycles for LIBs. Similarly, the electrode maintains a discharge capacity of 205 mA h g-1 at 100 mA g-1 after 500 cycles for KIBs. Moreover, when coupled with a high-mass-loading LiFePO4 cathode to design full cells, the HCNS-800‖LiFePO4 cells provide a specific discharge capacity of 139 mA h g-1 at 0.1 C. These results indicate that the HCNS electrode has promising potential for use in high-energy and environmentally sustainable lithium-based and potassium-based batteries.