Engineering of yolk-shelled FeSe2@nitrogen-doped carbon as advanced cathode for potassium-ion batteries

Potassium-ion batteries (KIBs) have become the most promising alternative to lithium-ion batteries for large-scale energy storage system due to their abundance and low cost. However, previous reports focused on the intercalation-type cathode materials usually showed an inferior capacity, together with a poor cyclic life caused by the repetitive intercalation of large-size K-ions, which hinders their practical application. Here, we combine the strategies of carbon coating, template etching and hydrothermal selenization to prepare yolk-shelled FeSe₂@N-doped carbon nanoboxes (FeSe₂@C NBs), where the inner highly-crystalline FeSe₂ clusters are completely surrounded by the self-supported carbon shell. The integrated and highly conductive carbon shell not only provides a fast electron/ion diffusion channel, but also prevents the agglomeration of FeSe₂ clusters. When evaluated as a conversion-type cathode material for KIBs, the FeSe₂@C NBs electrode delivers a relatively high specific capacity of 257 mAh/g at 100 mA/g and potential platform of about 1.6 V, which endow a high energy density of about 411 Wh/kg. Most importantly, by designing a robust host with large internal void space to accommodate the volumetric variation of the inner FeSe₂ clusters, the battery based on FeSe₂@C NBs exhibits ultra-long cycle stability. Specifically, even after 700 cycles at 100 mA/g, a capacity of 221 mAh/g along with an average fading rate of only 0.02% can be retained, which achieves the optimal balance of high specific capacity and long-cycle stability.     

Low-coordination water Prussian white as cathode for high-performance potassium-ion batteries

Prussian whites(PWs) with a three-dimensional framework can accommodate the insertion and extraction of ions with large radius,which have been widely used in potassium ion batteries.However,PWs show the poor cycling performance and inferior rate ability because of high coordinated water.In this work,PWs with different water content were synthesized via a coprecipitation method by controlling the reaction temperature.The sample with low-coordination water prohibits the best electrochemical performance.It shows a high capacity of 120.5 mAh/g at 100 mA/g for potassium-ion batteries(KIBs).It also exhibits a good rate performance,displaying a capacity of 73.2 mAh/g at 500 mA/g.     

Nickel tetrathiooxalate as a cathode material for potassium batteries

We report a nickel tetrathiooxalate (NiTTO) coordination polymer as a cathode material for potassium batteries. In a potential range of 1.3–3.6 V vs. K⁺/K, the specific capacity of the material is 209 mA h g^?1 at a current density of 0.1 A g^?1, which roughly corresponds to the two-electron reduction of polymer repeating units. The charge–discharge mechanisms of NiTTO in potassium cells were examined using operando Raman spectroscopy.     

Thermal explosion synthesis of LiFePO4 as a cathode material for lithium ion batteries

Research on Chemical Intermediates - Olivine-type LiFePO4 cathode material was successfully synthesized by a simple method of thermal explosion (TE) using hexamethylenetetramine (C6H12N4) as fuel....     

Electrochemically activated MnO as a cathode material for sodium-ion batteries

Besides classical electrode materials pertaining to Li-ion batteries, recent interest has been devoted to pairs of active redox composites having a redox center and an intercalant source. Taking advantage of the NaPF₆ salt decomposition above 4.2 V, we extrapolate this concept to the electrochemical in situ preparation of F-based MnO composite electrodes for Na-ion batteries. Such electrodes exhibit a reversible discharge capacity of 145 mAh g^− 1 at room temperature. The amorphization of pristine MnO electrode after activation is attributed to the electrochemical grinding effect caused by substantial atomic migration and lattice strain build-up upon cycling.     

A graphene-amorphous FePO4 hollow nanosphere hybrid as a cathode material for lithium ion batteries

Amorphous FePO(4) hollow nanospheres were directly grown on graphene for use as a cathode material in lithium ion batteries. This hybrid exhibits high rate capability and good cycle stability because of efficient Li(+) ion diffusion through the thin wall of the hollow nanospheres and fast electron transport through the graphene.     

CuP2 as high-capacity and long-cycle-life anode for potassium-ion batteries

Metal phosphides have shown great potential for potassium-ion batteries because of their high theoret-ical specific capacity.Nevertheless,most of the metal phos...     

Rapid synthesis of layered KxMnO2 cathodes from metal–organic frameworks for potassium-ion batteries

Layered transition metal oxides (LTMOs) are a kind of promising cathode materials for potassium-ion batteries because of their abundant raw materials and high theoretical capacities. However, their synthesis always involves long time calcination at a high temperature, leading to low synthesis efficiency and high energy consumption. Herein, an ultra-fast synthesis strategy of Mn-based LTMOs in minutes is developed directly from alkali-transition metal based-metal–organic frameworks (MOFs). The phase transformation from the MOF to LTMO is systematically investigated by thermogravimetric analysis, variable temperature optical microscopy and X-ray diffraction, and the results reveal that the uniform distribution of K and Mn ions in MOFs promotes fast phase transformation. As a cathode in potassium-ion batteries, the fast-synthesized Mn-based LTMO demonstrates an excellent electrochemical performance with 119 mA h g⁻¹ and good cycling stability, highlighting the high production efficiency of LTMOs for future large-scale manufacturing and application of potassium-ion batteries.

An ultra-fast synthesis method for layered transition metal oxide cathodes (K_xMnO₂) was developed via minute calcination of metal–organic frameworks for potassium-ion batteries.     

Designing N-doped graphene/ReSe_2/Ti_3C_2 MXene heterostructure frameworks as promising anodes for high-rate potassium-ion batteries

Developing high-performance anodes for potassium ion batteries(KIBs) is of paramount significance but remains challenging.In the normal sense,electrode materials are prepared by ubiquitous wet chemical routes,which otherwise might not be versatile enough to create desired heterostructures and/or form clean interfacial areas for fast transport of K-ions and electrons.Along this line,rate capability/cycling stability of resulting KIBs are greatly handicapped.Herein we present an all-chemical vapor deposition approach to harness the direct synthesis of nitrogen-doped graphene(NG)/rhenium diselenide(ReSe_2)hybrids over three-dimensional MXene supports as superior heterostructure anode material for KIBs.In such an innovative design,1 T'-ReSe2 nanoparticles are sandwiched in between the NG coatings and MXene frameworks via strong interfacial interactions,thereby affording facile K~+ diffusion,enhancing overall conductivity,boosting high-power performance and reinforcing structural stability of electrodes.Thus-constructed anode delivers an excellent rate performance of 138 mAh g^-1 at 10.0 A g^-1 and a high reversible capacity of 90 mAh g^-1 at 5 A g^-1 after 300 cycles.Furthermore,the potassium storage mechanism has been systematically probed by advanced in situlex situ characterization techniques in combination with first principles computations.     

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 hydrolyzationsulfuration 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.     

A polythiophene derivative bearing TEMPO as a cathode material for rechargeable batteries

A polythiophene derivative bearing TEMPO radical was synthesized by oxidative chemical polymerization of its monomer. The polymer had a high spin density (2.05 × 10²¹ spins/g of polymer). CV studies of the polymer showed that the electrochemical redox reaction of the TEMPO radicals were completely reversible. We demonstrated, for the first time, construction and charge/discharge characteristics of an organic radical battery utilizing a TEMPO bearing polythiophene based cathode material. The battery had an initial specific discharge capacity of 79 A h/kg (87% of the theoretical capacity) and an average output voltage of 3.6 V. The specific energy capacity initially discharged was 268 W h/kg.     

LiMn2O4 nanorods as a super-fast cathode material for aqueous rechargeable lithium batteries

LiMn₂O₄ nanorods were prepared by a facile hydrothermal method in combination with traditional solid-state reactions and characterized by X-ray diffraction analysis. Their electrochemical behavior was tested by cyclic voltammetry and repeated charge/discharge cycling. Results show that the reversible intercalation/deintercalation of Li-ions into/from LiMn₂O₄ cathode can yield up to 110 mAh/g at 4.5 C, and still retains 88% at the very large charge rate of 90 C with well-defined charge and discharge plateaus. It presents very high power density, up to 14.5 kW/kg, and very excellent cycling behavior, 94% capacity retention after 1200 cycles. It is thus a competitor for LiFePO₄.     

Preparation of spherical spinel LiMn2O4 cathode material for lithium ion batteries

A novel process is proposed for synthesis of spinel LiMn₂O₄ with spherical particles from the inexpensive materials MnSO₄, NH₄HCO₃, and NH₃H₂O. The successful preparation started with carefully controlled crystallization of MnCO₃, leading to particles of spherical shape and high tap density. Thermal decomposition of MnCO₃ was investigated by both DTA and TG analysis and XRD analysis of products. A precursor of product, spherical Mn₂O₃, was then obtained by heating MnCO₃. A mixture of Mn₂O₃ and Li₂CO₃ was then sintered to produce LiMn₂O₄ with retention of spherical particle shape. It was found that if lithium was in stoichiometric excess of 5% in the calcination of spinel LiMn₂O₄, the product had the largest initial specific capacity. In this way spherical particles of spinel LiMn₂O₄ were of excellent fluidity and dispersivity, and had a tap density as high as 1.9 g cm^–3 and an initial discharge capacity reaching 125 mAh g^–1. When surface-doped with cobalt in a 0.01 Co/Mn mole ratio, although the initial discharge capacity decreased to 118 mAh g^–1, the 100th cycle capacity retention reached 92.4% at 25°C. Even at 55°C the initial discharge capacity reached 113 mAh g^–1 and the 50th cycle capacity retention was in excess of 83.8%.     

Facile fabrication of MoP nanodots embedded in porous carbon as excellent anode material for potassium-ion batteries

Molybdenum phosphide(MoP),owing to its abundant reserve and high theoretical capacity,is regarded as a promising anode material for potassium-ion batteries.However,it still suffers from the problems of acute volume expansion and weak diffusion kinetics.This study reports a simple method to synthesize a composite of molybdenum phosphide and porous carbon(MoP@PC)through simple mixing and annealing treatment.In the MoP@PC,lots of MoP nanodots with an average diameter of about 4 nm uniformly embedded in the petal-like porous carbon.The MoP@PC shows reversible capacities of 330 mAh g^-1 at100 mA g^-1 after 100 cycles,and ultra-long cycling stability with a capacity of 240 mAh g^-1 after 1000 cycles at 1 A g^-1 and 161 mAh g^-1 after 1000 cycles at 5 A g^-1.The structure of MoP@PC after charging-discharging cycles is also investigated by high resolution transmission electron microscope(HRTEM)and the result shows that MoP can still maintain the nanodot morphology without any agglomeration after 1000 cycles at 5 A g^-1.The storage mechanism of potassium ions was studied as well,which reveals that MoP and potassium ion have a conversion reaction.     

Olivine LiCoPO4 phase grown LiCoO2 cathode material for high density Li batteries

Olivine LiCoPO₄ phase grown LiCoO₂ cathode material was prepared by mixing precipitated Co₃(PO₄)₂ nanoparticles and LiCoO₂ powders in distilled water, followed by drying and annealing at 120 °C and 700 °C, respectively, for 5 h. As opposed to ZrO₂ or AlPO₄ coatings that showed a clearly distinguishable coating layer from the bulk materials, Co₃(PO₄)₂ nanoparticles were completely diffused into the surface of the LiCoO₂ and reacted with lithium of LiCoO₂. An olivine LiCoPO₄ phase was grown on the surface of the bulk LiCoO₂, with a thickness of ∼7 nm. The electrochemical properties of the LiCoPO₄ phase, grown in LiCoO₂, had excellent cycle life performance and higher working voltages at a 1C rate than the bare sample. More importantly, Li-ion cells, containing olivine LiCoPO₄, grown in LiCoO₂, showed only 10% swelling at 4.4 V, whereas those containing bare sample showed a 200% increase during storage at 90 °C for 5 h. In addition, nail penetration test results of the cell containing olivine LiCoPO₄, grown in LiCoO₂ at 4.4 V, did not exhibit thermal runaway with a cell surface temperature of ∼80 °C. However, the cell containing bare LiCoO₂ showed a burnt-off cell pouch with a temperature above 500 °C.     

液相法合成锂离子电池正极材料Li_(1+x)Mn_2O_4

采用柠檬酸络合和溶液浸渍两种方法制备Li1+xMn2 O4正极材料 ,用XRD和BET测试了材料晶体结构和比表面积 ,考察焙烧温度、Li/Mn比、起始原料对产物结构和电化学性能的影响 ,结果表明 ,焙烧温度与Li/Mn比是影响材料电化学性能的关键因素 ,确定了制备Li1+xMn2 O4材料最佳条件为 0≤x≤ 0 .0 5 ,焙烧温度 75 0°C ,所得电池材料首次充放电容量达到 1 2 0mAh/g .循环 5 0次后 ,其充放电容量为 1 1 5mAh/g .     

LiNbO3-coated LiCoO2 as cathode material for all solid-state lithium secondary batteries

The further enhancement of high-rate capabilities for all solid-state lithium secondary batteries is reported. A LiNbO₃ layer of nanometer thickness was interposed between LiCoO₂ and sulfide solid electrolyte as buffer layer. This greatly reduced the interfacial resistance in the cathode and enhanced the high-rate capabilities of solid-state lithium batteries, providing good prospects for practical application of lithium secondary batteries free from safety issues.     

Ultrafine SnSSe/multilayer graphene nanosheet nanocomposite as a high-performance anode material for potassium-ion half/full batteries

Layer-structured SnSSe attracts much attention as an anode material for potassium storage due to its large theoretical capacity.Unfortunately,their practical ap...