Reversible Discharge Specific Capacity Research Articles

In-situ Ti4+-doped modification of layer-structured Ni-rich LiNi0.83Co0.11Mn0.06O2 cathode materials for high-energy lithium-ion batteries

The further commercialization of layer-structured Ni-rich LiNi0.83Co0.11Mn0.06O2 (NCM83) cathode for high-energy lithium-ion batteries (LIBs) has been challenged by severe capacity decay and thermal instability owing to the microcracks and harmful phase transitions. Herein, Ti4+-doped NCM83 cathode materials are rationally designed via a simple and low-cost in-situ modification method to improve the crystal structure and electrode–electrolyte interface stability by inhibiting irreversible polarizations and harmful phase transitions of the NCM83 cathode materials due to Ti4+-doped forms stronger metal-O bonds and a stable bulk structural. In addition, the optimal doping amount of the composite cathode material is also determined through the results of physical characterization and electrochemical performance testing. The optimized Ti4+-doped NCM83 cathode material presents wider Li+ ions diffusion channels (c = 14.1687 Å), lower Li+/Ni2+ mixing degree (2.68 %), and compact bulk structure. The cell assembled with the optimized Ti4+-doped NCM83 cathode material exhibits remarkable capacity retention ratio of 95.4 % after 100cycles at 2.0C and room temperature, and outstanding reversible discharge specific capacity of 148.2 mAh g−1 at 5.0C. Even under elevated temperature of 60 °C, it delivers excellent capacity retention ratio of 92.2 % after 100cycles at 2.0C, which is significantly superior to the 47.9 % of the unmodified cathode material. Thus, the in-situ Ti4+-doped strategy presents superior advantages in enhancing the structural stability of Ni-rich cathode materials for LIBs.

Fluorine-doped Na0.65MnO2 with a layer-tunnel structure for high-rate and long-cycle-life sodium-ion cathodes

Sodium-ion batteries (SIBs) exhibit comprehensive advantages in excellent cycling stability and high-rate performance. In this work, we present a novel cathode with a layered-tunnel coexisted structure with F ions, denoted as Na0.65MnO2-xFx. This material was confirmed the coexistence of layered and rod-like tunnel structures by advanced characterization methods. Due to the high specific capacity of the layered structure and the cycling stability of the rod-like tunnel structure, the Na0.65MnO2-xFx (x=0.2) cathode material exhibits outstanding comprehensive performance. At a rate of 0.1 C, the reversible discharge specific capacity is 124.6 mAh g−1, and notably, after 1000 cycles at a high rate of 10 C, the specific capacity is 55.9 mAh g−1 with a capacity retention rate of 98.2 %. This is significantly higher than the 34.1 mAh g−1 and 48.3 % capacity retention of pristine Na0.65MnO2. The introduction of F leads to an increase in the spacing between the oxide layers, the formation of strong metallic bonds and the formation of composite structures, which not only enhances the stability of the transition metal layer structure but also induces complex changes in the microstructure. This approach of ion doping and microstructure optimization provides a fresh perspective for the design and optimization of high-performance materials for SIBs.

Constructing heterojunction-induced oxygen vacancies of N-doped carbon-encapsulated Sn/SnOx microplates for boosting lithium storage capability

Heterogeneous Sn/SnOx@N-doped carbon (Sn/SnOx@NC) microplates with oxygen vacancies evolved from plate-like SnO powders are successfully fabricated, in which SnO powders are converted into Sn, SnO2, and Sn2O3 phases by rationally sintering and are perfectly in situ encapsulated by polyaniline-derived NC layer. By elaborately constructing the particular structure, high discharge specific capacity of 730.4 mAh/g and capacity retention ratio of 98.3 % after 110 cycles at 0.1 A/g are realized for optimal Sn/SnOx@NC composite electrode. Benefiting from enhanced electronic conductivity and Li+ ions diffusion kinetics, the assembled cell delivers reversible discharge specific capacity of 487.3 mAh/g at 1.0 A/g after 500 cycles. First principles calculation and in/ex situ characterization reveal that in situ formed heterostructure with oxygen vacancies and NC layer synergistically improve interfacial charge transfer and reaction reversibility to promote lithium storage capability. Therefore, fabricating Sn/SnOx@NC microplates may provide a practical strategy to design heterogeneous and oxygen-deficient Sn-based anode materials for high-performance lithium-ion batteries.

Modification of LiMn0·6Fe0·4PO4 lithium-ion battery cathode materials with a fluorine-doped carbon coating

In this study, glucose and NH4F were utilized as sources of carbon and fluorine, respectively, for the synthesis of LiMn0·6Fe0·4PO4 (LMFP) nanoscales. These nanoscales were subsequently modified with varying levels of fluorine-doped carbon through co-precipitation and mechanical ball milling processes. The LMFP, incorporating carbon and varying levels of fluoride ions, exhibit higher specific discharge capacities at 0.2 Cand electrochemical characteristics compared to the original LMFP coated solely with carbon. The inclusion of fluorine-doped carbon in the composite material creates numerous pathways for expeditious electron transfer. Moreover, the partial formation of metal fluoride at the interface between the surface of LMFP and the layer of carbon coating doped with fluorine enhances the reduction in the charge-transfer resistance. The modified ferromanganese phosphate cathode material reveals an outstanding discharge capacity displaying a reversible discharge specific capacity value of 131.73 mA h g−1 at 10C and 154.6 mA h g−1 at 0.2C, due to its unique structure.

Conjugation and Topology Engineering of 2D π‐d Conjugated Metal–Organic Frameworks for Robust Potassium Organic Batteries

AbstractThe evolution of two‐dimensional conjugated metal–organic frameworks (2D c‐MOFs) provides a significant prospect for researching the next generation of green and advanced energy storage systems (ESSs). Especially, conjugation and topology engineering serve as an irreplaceable character in adjusting the electrochemical properties of ESSs. Herein, we proposed a novel strategy using conjugation and topology engineering to demonstrate the application of 2D c‐MOFs in robust potassium‐ion batteries (PIBs) for the first time. By comparing 2D c‐MOFs with the rhombus/kagome structure as well as three/four‐arm core, the rhombus structure (sql‐Cu‐TBA‐MOF) cathode for PIBs can display the impressive electrochemical performance, including a high specific discharge capacity of 178.4 mAh g−1 (at 0.2 A g−1) and a well long‐term cycle stability of more than 9,000 (at 10.0 A g−1). Moreover, full PIBs (FPIBs) are constructed by pairing sql‐Cu‐TBA‐MOF cathode with dipotassium terephthalate (KTP) anode, which delivers a high reversible discharge specific capacity of 146.6 mAh g−1 (at 0.1 A g−1) and great practical application prospect. These findings provide reasonable implications for the design of 2D c‐MOFs from the perspective of conjugation and topology engineering for advanced energy storage systems.

Conjugation and Topology Engineering of 2D π-d Conjugated Metal-Organic Frameworks for Robust Potassium Organic Batteries.

The evolution of two-dimensional conjugated metal-organic frameworks (2D c-MOFs) provides a significant prospect for researching the next generation of green and advanced energy storage systems (ESSs). Especially, conjugation and topology engineering serve as an irreplaceable character in adjusting the electrochemical properties of ESSs. Herein, we proposed a novel strategy using conjugation and topology engineering to demonstrate the application of 2D c-MOFs in robust potassium-ion batteries (PIBs) for the first time. By comparing 2D c-MOFs with the rhombus/kagome structure as well as three/four-arm core, the rhombus structure (sql-Cu-TBA-MOF) cathode for PIBs can display the impressive electrochemical performance, including a high specific discharge capacity of 178.4 mAh g-1 (at 0.2 A g-1) and a well long-term cycle stability of more than 9,000 (at 10.0 A g-1). Moreover, full PIBs (FPIBs) are constructed by pairing sql-Cu-TBA-MOF cathode with dipotassium terephthalate (KTP) anode, which delivers a high reversible discharge specific capacity of 146.6 mAh g-1 (at 0.1 A g-1) and great practical application prospect. These findings provide reasonable implications for the design of 2D c-MOFs from the perspective of conjugation and topology engineering for advanced energy storage systems.

Ni-Co MOF-derived rambutan-like NiCo2O4/NC composite anode materials for high-performance lithium storage

Taking advantage of the large surface area and high porosity characteristic of metal-organic framework (MOF) materials, the synthesis of carbon-coated bimetallic transition metal oxides stands out as an effective strategy to reduce volume expansion, enhance cycling stability, and improve electronic conductivity at the active sites in lithium-ion batteries (LIBs). In this research, a novel rambutan-like Ni-Co MOF was successfully synthesized via a hydrothermal method followed by calcination to obtain nitrogen-doped carbon-stabilized hierarchical rambutan-like NiCo2O4 composites (NiCo2O4/NC). The resulting composites inherited the original rambutan-like structure of the Ni-Co MOF, which was characterized by uniform size, highly ordered porosity and large surface area, and showed excellent electrochemical Li+ storage performance. In particular, the NiCo2O4/NC-600 composite exhibited superior cyclic stability and rate capability, maintaining a remarkable reversible charge/discharge specific capacity of 1281.7/1292.7 mAh g−1 after 400 cycles at 0.5 A g−1. In addition, when paired with LiFePO4 in a full cell, it maintained a reversible discharge specific capacity of 143.9 mAh g−1 after 200 cycles at 0.1 A g−1, indicating commendable cyclic stability. Ex-situ analyses confirmed the pseudo-capacitive behavior of the NiCo2O4/NC composites. Furthermore, the nitrogen-doped carbon layer embedded in the NiCo2O4/NC composites effectively mitigated the volume expansion during repeated Li stripping/plating processes, thereby improving the structural integrity, conductivity, and specific capacitance. This study presents a practical approach for fabricating nitrogen-doped carbon-stabilized bimetallic oxide anodes in high-power LIBs through architectural engineering and compositional tailoring.

Nitrogen-doped graphene-decorated FeSex-Sb2Se3/C nanofibers as advanced anode materials for potassium ion batteries

Low operating voltage, high theoretical capacity conversion alloyed anodes ideal for potassium ion anodes. However, how to address the structural deformation and volume expansion of the changed alloyed materials throughout the reaction process is a crucial topic. A novel nitrogen-doped graphene-decorated FeSex-Sb2Se3/C nanofibers (FeSbSe-NGCNFs) composite is synthesized by adding dicyandiamide (DCDA) during electrospinning. Benefiting from porous one-dimensional nanostructure, graphene-decoration and rich nitrogen doping, the best electrochemical performance is shown by FeSbSe-NGCNFs when used as an anode in PIBs. FeSbSe-NGCNFs provide a reversible discharge specific capacity of 279.9 mAh/g at 100 mA g−1 after 100 cycles with a capacity retention of 87.6 %, in addition to a high capacity of 169.9 mAh/g at a high current of 3000 mA g−1. After 1000 cycles, the composite retained 115.8 mAh/g of capacity at 1000 mA g−1. The main causes of these exceptional cycling multiplicity properties are the porous structure that produces more carbon defects and active sites, increasing the amount of storage capacity for K+ and speeding up K+ transport and electron transfer, as well as the graphene nanosheet structure that enhances electrical conductivity and increases its specific surface area. Therefore, PIBs might benefit from the developed FeSbSe-NGCNFs as anode material.

MOF-Derived Bimetallic Selenide CoNiSe2 Nanododecahedrons Encapsulated in Porous Carbon Matrix as Advanced Anodes for Lithium-Ion Batteries.

Transition metal selenides have received considerable attention as promising candidates for lithium-ion battery (LIB) anode materials due to their high theoretical capacity and safety characteristics. However, their commercial viability is hampered by insufficient conductivity and volumetric fluctuations during cycling. To address these issues, we have utilized bimetallic metal-organic frameworks to fabricate CoNiSe2/C nanodecahedral composites with a high specific surface area, abundant pore structures, and a surface-coated layer of the carbon-based matrix. The optimized material, CoNiSe2/C-700, exhibited impressive Li+ storage performance with an initial discharge specific capacity of 2125.5 mA h g-1 at 0.1 A g-1 and a Coulombic efficiency of 98% over cycles. Even after 1000 cycles at 1.0 A g-1, a reversible discharge specific capacity of 549.9 mA h g-1 was achieved. The research highlights the synergistic effect of bimetallic selenides, well-defined nanodecahedral structures, stable carbon networks, and the formation of smaller particles during initial cycling, all of which contribute to improved electronic performance, reduced volume change, increased Li+ storage active sites, and shorter Li+ diffusion paths. In addition, the pseudocapacitance behavior contributes significantly to the high energy storage of Li+. These features facilitate rapid charge transfer and help maintain a stable solid-electrolyte interphase layer, which ultimately leads to an excellent electrochemical performance. This work provides a viable approach for fabricating bimetallic selenides as anode materials for high-performance LIBs through architectural engineering and compositional tailoring.

Carbon-reinforced Ni3S2/Ti3C2Tx MXene composite as an anode for superior-performance lithium-ion capacitors

Lithium ion capacitors (LICs) are a new generation of energy storage devices that combine the super energy storage capability of lithium ion batteries with the satisfactory power density of supercapacitors. The development of high-performance LICs still faces great challenges due to the unbalanced reaction kinetics at the anode and cathode. Therefore, it is an inevitable need to enhance the electron/ion transfer capability of the anode materials. In this paper, to obtain a superior-rate and high-capacity Ni3S2-based anode, highly conductive Ti3C2Tx MXene sheets were introduced to sever as the carrier of Ni3S2 nanoparticles and simultaneously an amorphous carbon layer which coats onto the surface of Ni3S2 nanoparticles was in-situ generated by the carbonization of dopamine reactant. The as-synthesized Ni3S2/Ti3C2Tx/C composite exhibits a high specific surface area (112.6 m2/g) because of the addition of Ti3C2Tx that can reduce the aggregation of Ni3S2 nanoparticles and the in-situ generated amorphous carbon layer that can suppress the growth of Ni3S2 nanoparticles. The Ni3S2/Ti3C2Tx/C anode possesses a remarkable reversible discharge specific capacity (626.0 mAh/g under 0.2 A/g current density), which increases to 1150.8 mAh/g after 400-cycle charge/discharge measurement at the same measurement condition indicating eminent cyclability, along with superior rate capability. To construct a superior-performance LIC device, a sterculiae lychnophorae derived porous carbon (SLPC) cathode with an average discharge specific capacity of 73.4 mAh/g@0.1A/g was prepared. The Ni3S2/Ti3C2Tx/C//SLPC LIC device with optimal cathode/anode mass ratio has a satisfactory energy density ranging from 32.8 to 119.1 Wh kg−1 at the corresponding power density of 8799.4 to 157.5 W kg−1, together with a prominent capacity retention (95.5 %@1 A/g after 10,000 cycles).

Yttrium doping improves stability of manganese dioxide cathode for aqueous zinc ion batteries

Manganese-based oxides are a promising cathode material for aqueous zinc ion batteries. However, structural change and irreversible dissolution of manganese in manganese-based oxides during charging and discharging lead to poor cycling stability, which hinders their large-scale application. Elemental doping is an effective way to regulate the bonding strength and crystal structure of the material. In this paper, YMO materials with nanorod-like structures have been obtained by a hydrothermal method. Y-element doping enhances the stability of the material and improves the electronic and ionic conductivity of the material. The YMO material exhibits excellent electrochemical performance as a cathode material for aqueous zinc ion batteries. The electrode exhibits a high reversible discharge specific capacity of 409.3 mAh g−1 at a current density of 0.1 A g−1, and the electrode capacity hardly decays after 100 charge/discharge cycles, meanwhile, the YMO electrode shows good initial cycling stability even at different charge/discharge current densities. In addition, the YMO electrodes showed long-term cycling stability, with a capacity retention rate of 95.1% after 2000 cycles at a current density of 1 A g−1. The excellent cycling stability of the electrode is mainly due to the improved structural stability of YMO, which is related to the stronger YO bonds acting as anchors in the lattice structure of MnO2. Meanwhile, the strong interaction between doped Y3+ and O2− promotes the storage of H+. Structurally stable electrode materials obtained by optimizing doping elements to modulate bonding energy is an effective way to improve the stability of manganese-based materials.

Multi-functional additive to enhance cycling performance of Zn anode in aqueous battery

The growth of dendritic dendrites and side reactions at the zinc anode result in poor cycling stability of the aqueous zinc-ion battery (AZIBs). Here, we report on a multifunctional additive, Sodium lactobionate (SL), that achieves more stable cycling performance. SL molecule can loosen the solvation structure of water and Zn2+, inhibit corrosion and hydrogen evolution reactions, and regulate ion deposition in AZIBs. Under the action of SL, the Zn//Zn symmetric battery achieves an ultra-long stable cycle of up to 2150 h at a current density of 2 mA·cm−2 and an area capacity of 1 mAh cm−2 and Zn//NVO can still perform 1110 cycles at the current density of 2 A g−1 and maintain the reversible specific discharge capacity of 179 mAh g−1. In addition, at 2 mA cm−2 and 0.5 mAh cm−2, the Zn//Cu asymmetric battery achieved up to 350 cycles with a coulomb efficiency of 99.5 %.

C@SnS2 core-shell 0D/2D nanocomposite with excellent electrochemical performance as lithium-ion battery anode

C@SnS2 core-shell 0D/2D nanocomposite was successfully prepared by a one-step hydrothermal method. The SnS2 nanosheets were heterogeneously nucleated and grown on the surface of carbon spheres. As an anode for lithium-ion batteries, the electrochemical performance of the C@SnS2 composite outperforms that of SnS2 nanoflowers. After 100 cycles, the reversible discharge specific capacity reaches an impressive value of 802 mAh g−1 at a current density of 100 mA g−1. Even after 600 cycles, the discharge specific capacity remains a value of 442 mAh g−1, under a high current density of 1 A g−1. This remarkable lithium-ion storage performance can be attributed to the unique core-shell nanostructure and the synergy between SnS2 nanosheets and carbon spheres. This study advances our understanding of the vital role of carbon in fabricating nano-heterojunction or composite electrodes and provides a feasible route to significantly improve the electrochemical properties of SnS2 and other metal sulfides.

Electrosprayed hierarchical mesoporous Mn0.5Ti2(PO4)3@C microspheres as promising High-Performance anode for Potassium-Ion batteries

NASICON-structured Ti-based polyanion compounds benefit from a stable structural framework, large ion channels, and fast ion mobility. However, the large radius of potassium and its poor electronic conductivity restrict its use in potassium-ion batteries. Herein, hierarchical mesoporous Mn0.5Ti2(PO4)3@C microspheres have been successfully synthesized using a simple electrospraying method. These microspheres consist of Mn0.5Ti2(PO4)3 nanoparticles evenly embedded in three-dimensional mesoporous carbon microspheres. The hierarchical mesoporous micro/nanostructure facilitates the rapid insertion and extraction of K+, while the three-dimensional carbon microspheres matrix enhances electrical conductivity and prevents active materials from collapsing during cycling. So the hierarchical mesoporous Mn0.5Ti2(PO4)3@C microspheres exhibit a high reversible discharge specific capacity (306 mA h g−1 at 20 mA g−1), a notable rate capability (123 mA h g−1 at 5000 mA g−1), and exceptional cycle performance (148 mA h g−1 at 500 mA g−1 after 1000 cycles). The results show that electrosprayed Mn0.5Ti2(PO4)3@C microspheres are a promising anode for PIBs.

Facilely construction of multistage channel in PVDF-HFP for high ionic conductivity and prominent anti-lithium dendrites

Safety concerns such as lithium dendrite growth, leakage and volatilization regularly plague conventional liquid lithium metal batteries. However, solid polymer electrolytes can mitigate these issues due to their chemical and electrochemical stability. In this paper, we show that the construction of porous structures gives PVDF-HFP based polymers excellent solution retention, quick Li+ transport channels, and ultra-long Li-symmetric cycle stability. PVDF-HFP based electrolyte membrane with porous structure exhibits excellent electrolyte retention (129.5 %) and superior ionic conductivity (2.4 × 10-3 S cm−1 at 20 ℃). In addition, Lithium-symmetric half battery uses the DPH250 porous electrolyte film to stably last more than 2000 h during the lithium plating/stripping process. DI regulation of PVDF-HFP electrolyte membrane is beneficial to achieve uniform lithium deposition, and better solve the interface problems existing in solid state batteries. LiFePO4/DPH250-LiPF6/Li batteries exhibit stable cycling performance and reversible specific discharge capacity, suggesting a potential strategy for stabilizing lithium metal batteries.

Single atom iron as an efficient electrocatalyst for enhanced kinetics in magnesium-sulfur batteries

Magnesium-sulfur battery (MSB) with the advantages of low cost, high theoretical energy density and high security is regarding as a promising energy storage system. However, it suffers from sluggish reaction kinetics, fast capacity fading and poor cycling stability due to the shortage of compatible electrolyte and high performance cathode. Herein, Fe single atom catalyst is introduced to improve the electrochemical performance of MSB for the first time. Fe atoms are uniformly dispersed on graphene support by a facile method to prepare Fe-N-G, which is applied as an effective sulfur host. Benefited from the remarkable catalytic performance of the single-atom Fe, the produced S@ Fe-N-G exhibits a high reversible discharge specific capacity of 962 mA h g−1 at 0.1C, outstanding cycling stability of maintaining 892.7 mA h g−1 at 0.3C after 200 cycles and excellent rate capability. It is expected that this work could promote the development of more high-efficient single-atom catalysts for high performance MSB.

In situ synthesis of HCNFs@SnS2 composite via solid-phase vulcanization reaction for high-performance anode of lithium-ion batteries

Tin-based oxides or sulfides are regarded as prospective anode materials for lithium-ion batteries owing to their high theoretical specific capacity, low-cost, and low insertion/extraction potential. However, their practical application is limited duo to the poor intrinsic conductivity and tremendous volume expansion/shrinkage during Li+ intercalation/deintercalation. In this study, a simple and controllable two-step method was used to design and prepare the novel SnS2@helical carbon nanofibers (HCNFs@SnS2) anode composite, in which the size and content of SnS2 nanoparticles are about 10 nm and 62.67%, respectively. The HCNFs@SnS2 anode exhibits a superior reversible discharge specific capacity of 901.6 mAh/g (about seven times as many as HCNFs@SnO2), higher capacity retention rate of 69.1 % after 100 cycles at 200 mA/g, and an excellent ultra-long cycle capacity of 470.9 mAh/g at 2000 mA/g after 1000 cycles. The outstanding electrochemical performance of HCNFs@SnS2 mainly benefits from the synergistic contribution between HCNFs matrix and SnS2, and especially the specific 3D helical structure of HCNFs effectively improves the volumetric expansion and conductivity of SnS2 nanoparticles. This work provides some novel insights and references for developing other transition metal-oxide/sulfide-based anode materials with significantly practical application potential in energy storage areas.

Selenium enriched over-oxidized Mo3Se4 decorated MXene as a high-performance Li-ion battery anode material

The anode materials in Li-ion battery (LIB) are key components that define the performance of the cell. We have developed new selenium enriched and over-oxidized Mo3Se4 decorated MXene (Mo3Se4@Ti3C2Tx) composite as a promising anode material for Li-ion battery (LIB). By using selective experimental conditions, Mo3Se4@ Ti3C2Tx was successfully developed with unique structural and morphological features. When being employed as anode material in LIB, Mo3Se4@Ti3C2Tx delivered high stable reversible specific discharge capacity of 1250 mAh/g at 0.1C, which is significantly higher than traditional carbon-based anode materials. In addition, the composite retained 84.53 % of initial specific capacity when the C-rate was increased from 0.1C to 1.5C, implying excellent rate performance. The Mo3Se4@Ti3C2Tx composite also demonstrated remarkable cycling stability with negligible loss after 378 cycles. This exceptional electrochemical performance can be assigned to the exclusive architecture of Mo3Se4@Ti3C2Tx composite, leading to increase in exposure of active Li+ sites and structural stability.

Beaded CoSe2-C Nanofibers for High-Performance Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries are regarded as highly promising energy storage devices due to their high theoretical specific capacity and high energy density. Nevertheless, the commercial application of Li-S batteries is still restricted by poor electrochemical performance. Herein, beaded nanofibers (BNFs) consisting of carbon and CoSe2 nanoparticles (CoSe2/C BNFs) were prepared by electrospinning combined with carbonization and selenization. Benefitting from the synergistic effect of physical adsorption and chemical catalysis, the CoSe2/C BNFs can effectively inhibit the shuttle effect of lithium polysulfides and improve the rate performance and cycle stability of Li-S batteries. The three-dimensional conductive network provides a fast electron and ion transport pathway as well as sufficient space for alleviating the volume change. CoSe2 can not only effectively adsorb the lithium polysulfides but also accelerate their conversion reaction. The CoSe2/C BNFs-S cathode has a high reversible discharge specific capacity of 919.2 mAh g-1 at 0.1 C and presents excellent cycle stability with a low-capacity decay rate of 0.05% per cycle for 600 cycles at 1 C. The combination of the beaded carbon nanofibers and polar metal selenides sheds light on designing high-performance sulfur-based cathodes.

Facile synthesis of pomegranate-like structured SiOx composite spheres with internal carbon conductive network for lithium-ion batteries

Incorporating carbon into unique structural particles is an effective way to further enhance cycle stability, the number of lithium-ion transfer channels within particles, and diffusion rate, but the procedure is intricate and challenging. The introduction of carbon into pomegranate-like SiO2 nanospheres is achieved by co-depositing SiO2 with carbon precursors to produce ultra-fine SiO2/C composite nanoparticles that replace the SiO2 nanoparticles that make-up the pomegranate spheres. The ultrafine SiO2/C composite nanoparticles encapsulated inside the sphere are connected to each other, creating a carbon-conductive network within the sphere. A mechanically stable outer carbon layer containing nitrogen is coated on the surface to form the (P-SiOx/CN)@CN composite material. The mechanically stable outer carbon layer, the reserved void space within the sphere, the core constructed by interconnected nanoparticles, and the carbon conductive network inside the sphere work together to endow the composite with superior electrochemical properties. The (P-SiOx/CN)@CN composite delivers high reversible mass discharge specific capacity of 970 mA h g−1 at 1.0 A g−1 over 500 cycles. This work develops a new approach to the facile synthesis of high-performance SiO2 anode materials for lithium-ion batteries.