Superior Lithium Storage Research Articles

Optimal microstructural design of pitch-derived soft carbon shell in yolk-shell silicon/carbon composite for superior lithium storage

Silicon-carbon composites have proved to be effective in addressing the issues of silicon anodes, however, few works focus on understanding the effect of the microstructure of the carbon component on their electrochemical performance. Herein, we prepare a series of yolk-shell structured silicon-carbon nanocomposites with adequate voids through a facile and scalable process. By deliberately selecting the pitch species and delicately adjusting the heat treatment temperature, the microcrystal texture and pore structure of the soft carbon can be easily tuned. Finally, a well matching of the crystalline and pore structure ensure the rapid charge transport and the good structural robustness, further endowing the optimal lithium storage, cycle performance and rate capability of the electrodes. The Si/C composite with an optimized carbon shell delivers a reliable cycle stability with a capacity retention ratio of 55% after 300 cycles at 0.2 A g−1 and a remained capacity of 743 mAh g−1 at a high current density of 2.0 A g−1. Importantly, the correlation between the lithium storage of the Si/C composites and the microstructure features (crystallinity and pores) of the carbon shell has been established, which may provide an effective guidance for optimizing the microstructure design of the promising Si/C anode materials.

Extrinsic‐Structured Bimetallic‐Phase Ternary Metal Phosphorus Trisulfides Coupled with N‐Doped Graphitized Carbon for Superior Electrochemical Lithium Storage

AbstractThe exploration of advanced electrode materials through rational structure/phase design is the key to develop high‐performance rechargeable batteries. Herein, ternary metal phosphorus trisulfides (NiCoPS3) with a bimetallic phase and an extrinsic structure of nanodots combined with nitrogen‐doped graphitized carbon (NC) are developed for lithium‐ion batteries. The designed NiCoPS3/NC holding a nanocube‐like morphology shows a set of structural/compositional advantages as lithium‐ion battery anodes including high electrical conductivity, low ion diffusion barrier, improved theoretical lithium storage capacity, and relieved lithiation stress, which are confirmed by characterizations and density functional theory calculations. As a consequence, the NiCoPS3/NC electrode displays superior comprehensive lithium storage performance, e.g., high reversible capacity (991 mAh g−1 at 0.1 A g−1), excellent cycling stability (up to 1200 cycles at 2 A g−1 and 2000 cycles at 5 A g−1 with respective capacity retention of over or nearly 100%), and good rate capability (58.4% capacity retention after a current change from 0.1 to 5 A g−1), representing the best comprehensive battery performance in MPS3‐based anodes to date.

Sulfur-doped mesoporous carbon activated by sodium sulfate as a superior performance anode for lithium ion batteries

Mesoporous carbon (MC) was activated by Na2SO4 to prepare sulfur-doped MC (S-MC) for superior lithium storage. Compared with MC, S-MC exhibits unique structure such as reduced particle size, doped S heteroatoms, developed mesopores, and narrowed pore size distributions. It makes S-MC deliver superior lithium storage performance. The first reversible capacity of S-MC is as high as 1197.2 mAh·g−1, which is much higher than that of MC (698.6 mAh·g−1). What is more, the rate capability of S-MC is much better than that of MC, and the charge capacity of S-MC is 303.4 mAh·g−1 at 1.5 A·g−1. The specific charge capacity of S-MC increases to 955.6 mAh·g−1 after 300 charge-discharge cycles, exhibiting excellent cycling performance. Our findings give a new way to modify porous carbon for superior lithium storage.

Interfacial Design on Graphene-Hematite Heterostructures for Enhancing Adsorption and Diffusion towards Superior Lithium Storage.

Hematite (α-Fe2O3) is a promising electrode material for cost-effective lithium-ion batteries (LIBs), and the coupling with graphene to form Gr/α-Fe2O3 heterostructures can make full use of the merits of each individual component, thus promoting the lithium storage properties. However, the influences of the termination of α-Fe2O3 on the interfacial structure and electrochemical performance have rarely studied. In this work, three typical Gr/α-Fe2O3 interfacial systems, namely, single Fe-terminated (Fe-O3-Fe-R), double Fe-terminated (Fe-Fe-O3-R), and O-terminated (O3-Fe-Fe-R) structures, were fully investigated through first-principle calculation. The results demonstrated that the Gr/Fe-O3-Fe-R system possessed good structural stability, high adsorption ability, low volume expansion, as well as a minor diffusion barrier along the interface. Meanwhile, investigations on active heteroatoms (e.g., B, N, O, S, and P) used to modify Gr were further conducted to critically analyze interfacial structure and Li storage behavior. It was demonstrated that structural stability and interfacial capability were promoted. Furthermore, N-doped Gr/Fe-O3-Fe-R changed the diffusion pathway and made it easy to achieve free diffusion for the Li atom and to shorten the diffusion pathway.

Metal–organic framework mediated nickel doped copper ferrite for superior lithium storage

A metal–organic framework mediated nickel doped ferrite composite with superior lithium storage properties was successfully synthesized. A DFT study also elucidated the reaction pathway for Cu1−xNixFe2O4.

Boosting Li/Na storage performance of graphite by defect engineering.

Regulating material properties by accurately designing its structure has always been a research hotspot. In this study, by a simple and eco-friendly mechanical ball milling, we could successfully engineer the defect degree of the graphite. Moreover, according to the accurate deconstruction of the structure by atomic pair distribution function analysis (PDF) and X-ray absorption near-edge structure analysis (XANES), those structural defects of the ball-milled graphite (BMG) mainly exist as carbon atom vacancies within the graphene structure, which are beneficial to enhance the lithium and sodium storage performance of BMG. Therefore, BMG-30 h exhibits superior lithium and sodium storage performance.

Copper niobate nanowires boosted by a N, S co-doped carbon coating for superior lithium storage.

With the development of electric vehicles, more and more attention has been paid to the kinetic performance of batteries, which is related to rapid charge/discharge and safety issues. To improve this aspect, Cu2Nb34O87 nanowires covered by nitrogen and sulfur co-doped carbon (Cu2Nb34O87/NSC nanowires) are prepared by electrospinning combined with surface coating. As-prepared Cu2Nb34O87/NSC nanowires present a high ion diffusion coefficient and electronic conductivity, showing good a kinetic performance. Specifically, they deliver a splendid capacity of 311.2 mA h g-1 at 1 C and a superior cycling stability with a capacity fading of 0.031% per cycle upon 1000 cycles. At the same time, the electrochemical and structural reversibility is fully discussed and demonstrated by ex situ XRD, ex situ SEM and ex situ XPS based on the redox couples of Cu2+/Cu+, Nb5+/Nb4+, and Nb4+/Nb3+. Contributing to peculiar physico-chemical properties, Cu2Nb34O87/NSC nanowires are expected to be a candidate material for the anode in lithium-ion batteries.

Self-templated formation of hierarchically yolk-shell-structured ZnS/NC dodecahedra with superior lithium storage properties.

Hierarchical ZnS/NC dodecahedra are successfully constructed via a two-step synthetic method combining a sulfidation process and subsequent carbonization treatment, benefiting from the inherent merits of zeolitic imidazolate frameworks as ideal precursors/self-sacrificing templates. Studies reveal that the sulfidation time plays a vital role in the morphological evolution and lithium storage performances of final products. To our knowledge, this is the first example of carbon-based ZnS hierarchical materials with yolk-shell structures. When used as anode materials for lithium-ion batteries (LIBs), the resultant ZnS(x h)/NC (x is the sulfidation time) electrodes showed high lithium storage abilities, excellent cycling stabilities, and good rate capabilities. The optimal ZnS(72 h)/NC sample shows a well-defined multi-yolk-shell structure and delivers a high reversible specific capacity (757 mA h g-1 after 100 cycles at 200 mA g-1), extraordinary rate capability, and intriguing long-term cycling stability (∼500 mA h g-1 at 2 A g-1 after 1000 cycles). Such a type of architecture simultaneously integrates several attractive design principles for high-performance LIB anodes including the yolk-shell structure, nitrogen-doped carbon coupling, and ultrafine ZnS nanoparticles.

Conjugated cyclized-polyacrylonitrile encapsulated carbon nanotubes as core–sheath heterostructured anodes with favorable lithium storage

Conjugated cyclized-polyacrylonitrile encapsulated conductive carbon nanotubes to form highly redox-active sheath–core heterostructured anodes with superior lithium storage capability.

Cu2Nb34O87 nanowires as a superior lithium storage host in advanced rechargeable batteries

Cu2Nb34O78 nanowires present a high charge capacity of 279.8 mA h g−1 with a Coulombic efficiency of 89.6% based on Nb5+/Nb4+, Nb4+/Nb3+ and Cu2+/Cu+ redox couples.

Superior rate-capability and long-lifespan carbon nanotube-in-nanotube@Sb2S3 anode for lithium-ion storage

Sb2S3 is successfully anchored inside a carbon nanotube-in-nanotube via a multi-step method based on metal–organic framework and carbon nanotubes. The composite exhibits superior lithium storage performance.

Regulation of nitrogen configurations and content in 3D porous carbons for improved lithium storage.

The incorporation of active nitrogen species in carbon materials has been widely demonstrated as a viable means to produce superior lithium storage materials, while the precise regulation of nitrogen configurations as well as their content still remains a formidable challenge. Herein, nitrogen-free porous carbon frameworks were synthesized by a self-templating strategy from disodium citrate, and post-annealing yielded 10.4 at% N that was primarily pyrrolic-N and pyridinic-N with an atomic ratio of about 3 : 1, with negligible inactive graphitic-N. A gravimetric capacity of 570 mA h g-1 at a current density of 4 A g-1 was measured for a Li half-cell based on the as-prepared N-doped 3D carbon materials. Lithium-ion capacitors with this N-doped carbon as the anode and commercial AC as the cathode yielded energy densities of 58.9 and 142.6 W h kg-1 with the corresponding power densities of 7400 and 185 W kg-1, respectively. We suggest that the carbon materials with high content of pyrrolic-N and pyridinic-N especially pyrrolic-N have improved lithium storage.

In-situ construction of g-C3N4/Mo2CTx hybrid for superior lithium storage with significantly improved Coulombic efficiency and cycling stability

Mo2CTx MXene, obtained by etching Ga from the Mo2Ga2C, is theoretically predicted to possess high electrochemical activity. However, the preparation of Mo2CTx remains challenging due to the difficultly of traditional HF etching. Increasing the exfoliation degree and constructing the protection layer of Mo2CTx not only can offer rich active sites but also suppress side reaction, which has been considered as efficient approaches to improving its electrochemical performance. In this work, a facile in-situ strategy was developed to synthesize the graphitic carbon nitride/Mo2CTx (g-C3N4/Mo2CTx) hybrid, smartly employing the conversion from urea to g-C3N4 to realize the exfoliation degree of Mo2CTx MXene and simultaneously build a protection layer. As expected, the abundant exposed MXene layers are believed to provide rapid diffusion pathways for the ions transport as well as rich active sites for lithium storage. As a result, the target g-C3N4/Mo2CTx hybrid exhibits a much higher Coulombic efficiency (70.8%) and superior lithium storage performance (525.8 mAh g−1) compared with pure Mo2CTx (19.2% and 101.4 mAh g−1). Generally, this synthesis strategy presented in this study paves a new way for the fabrication of MXene based hybrid with high performance for lithium storage.

Synergistic Interactions of Different Electroactive Components for Superior Lithium Storage Performance

The fusion of different electroactive components of lithium-ion batteries (LIBs) sometimes brings exceptional electrochemical properties. We herein report the reduced graphene-oxide (rGO)-coated Zn2SnO4z@NiO nanofibers (ZSO@NiO@G NFs) formed by the synergistic fusion of three different electroactive components including ZnO, SnO2, and NiO that exhibit exceptional electrochemical properties as negative electrodes for LIBs. The simple synthetic route comprised of electrospinning and calcination processes enables to form porous one-dimensional (1D) structured ZSO, which is the atomic combination between ZnO and SnO2, exhibiting effective strain relaxation during battery operation. Furthermore, the catalytic effect of Ni converted from the surface-functional NiO nanolayer on ZSO significantly contributes to improved reversible capacity. Finally, rGO sheets formed on the surface of ZSO@NiO NFs enable to construct electrically conductive path as well as a stable SEI layer, resulting in excellent electrochemical performances. Especially, exceptional cycle lifespan of more than 1600 cycles with a high capacity (1060 mAh g-1) at a high current density (1000 mA g-1), which is the best result among mixed transition metal oxide (stannates, molybdates, cobaltates, ferrites, and manganates) negative electrodes for LIBs, is demonstrated.

One dimensional SbO2/Sb2O3@NC microrod as anode for lithium‐ion and sodium‐ion batteries

AbstractSb‐based oxides electrodes have received tremendous attention owing to their high theoretical capacities and electrochemical activities. However, the huge volume change during ion insertion/extraction process and poor electronic conductivity limit their wide applications in the electrochemical energy storage. In this study, SbO2/Sb2O3 nanoparticles embedded in N‐doped carbon fibers are successfully synthesized. The composite can display a high reversible specific capacity of 622 mAh g−1 for lithium‐ion batteries and a desirable reversible capacity 307 mAh g−1 for sodium‐ion batteries at current density of 100 mA g−1. Such superior lithium and sodium storage performance can be ascribed to that carbon fibers can effectively restrict the large volume change and enhance the electrochemical stability.

In-situ grown flower-like C@SnO2/Cu2O nanosheet clusters on Cu foam as high performance anode for lithium-ion batteries

Tin dioxide (SnO2) is considered as one of promising anode materials in lithium-ion batteries due to its high specific discharge capacity, low cost and environmental friendliness. However, practical application of SnO2 is still hindered by severe capacity fading, poor cycling stability and inferior rate performance due to volume expansion during charge/discharge processes. To overcome this problem, composites of flower-like carbon layer (thickness: ~1.5 nm) enwrapped SnO2/Cu2O (thickness: ~20 nm; length: ~ 200 nm) anchored on Cu foam were in-situ synthesized by facile hydrothermal method and subsequent annealing. Compared with pure SnO2, such novel hierarchical structure effectively enhancs the conductivity and structural stability of the composites as integrated electrode for lithium-ion batteries. Electrochemical studies reveal superior lithium storage capability, cycle stability, and rate performance for C@SnO2/Cu2O nanosheet clusters with discharge capacity of 1726 mAh g−1 in first cycle and 814 mAh g−1 after 300 cycles at 0.5 C, as well as 425 mAh g−1 at 2 A g−1. Therefore, C@SnO2/Cu2O nanosheet clusters possess great potential for scientific research and future application in lithium-ion batteries.

Interconnected porous N-doped carbon coated cobalt/iron oxides core shell nanocomposites for superior lithium storage anode

The design and fabrication of transition metal oxides (TMOs) anode with superior lithium storage performance remains a challenge. Herein, we demonstrate one-pot hydrothermal method combined with post-calcination for the construction of interconnected porous N-doped carbon-coated cobalt/iron oxides nanocomposite (CFO@N-C) as lithium-ion batteries (LIBs) anode. This facile approach gives CFO@N-C many interesting characters such as rich porous structure, fine cobalt/iron oxides’ nanocrystals (<10 nm), interconnected carbon coating layer (~3–20 nm) and high nitrogen content (33.2 wt%, N/C). When evaluated as LIBs anodes, it rendered a reversible capacity of about 1218 mAh g−1 at 0.2 A g−1 after 100 cycles, a remarkable discharge capacity of about 376.8 mAh g−1 was retained after 400 cycles even at current density of 10 A g−1. Cyclic voltammetry revealed there exists a notable capacitive contribution, especially at high rate (74.2% at ~5C). Electrochemical impedance spectroscopy disclosed that CFO@N-C electrode possesses not only a low charge transfer resistance, but also a high Li diffusion coefficient, about 60 times that of pure cobalt ferrite electrode.

Fabrication of cactus-like CNT/SiO2/MoO3 ternary composites for superior lithium storage

Advanced electrode materials with high rate capability and long cycling stability are highly pursued for high-performance lithium-ion batteries (LIBs). In this study, cactus-like CNT/SiO2/MoO3composites are synthesized via self-assembly followed by in-situ carbonization, wherein the CNT, SiO2, and MoO3 are uniformed distributed. Such unique structure can effectively alleviate the strain during cycling, reduce the Li+ diffusion time, and provide more active sites for the interaction of ions, thus allowing much better rate capability. Specifically, CNTs act as the cactus veins to rapidly transport the electrons, while the SiO2 and MoO3 particles located in the cactus leaf-like region are used to store lithium. In addition, the MoO3 can play as a supporter to minimize the change of the whole structure and further stabilize the electrode because of the lower strain during lithiation. As a consequence, the CNT/SiO2/MoO3electrode delivers a high specific capacity (700 mAh g−1at 1000 mA g−1over 500 cycles) and long cycle life (320 mAh g−1at 5000 mA g−1within 800 cycles). It is possible that this research could provide new insights for developing novel anode materials with superior lithium storage capability.

One-step synthesis of nanoporous silicon @ graphitized carbon composite and its superior lithium storage properties

Nanoporous silicon @ graphitized carbon (NPSi@C) composites have been reasonably designed and synthesized via one-step magnesiothermic co-reduction using rice husks as the silicon source and CO2 as the carbon source. In the self-assembly process, the nano-silicon prepared from rice husk-derived SiO2 is made into a porous structure and uniformly recombined with graphitized carbon formed by CO2 reduction at low temperature (680 °C). The nanoporous structure has contributed to accommodate the large volume effect of activated silicon and provides sufficient channels for the transfer of lithium ions. Furthermore, the graphitized carbon layers effectively enhance the electrical conductivity and coulombic efficiency of the composites, which is conducive to the improvement of electrochemical performance. The optimized NPSi@C composite exhibits superior lithium storage properties with the initial coulombic efficiency of 41.0% and the reversible specific capacity of 681.8 mA h g−1 after 100 cycles at 0.2 A g−1. This study suggests a simple, low-cost, and scalable strategy, which maximizes the advantages of traditional magnesiothermic reduction, to the preparation of Si/C composites as the most promising alternative anode materials for lithium ion batteries.

Stable Lithium Storage at Subzero Temperatures for High‐capacity Co3O4@graphene Composite Anodes

AbstractAchieving high energy density and long‐term stability at subzero temperatures remains one of the main challenges for the development of lithium‐ion batteries. Shortcomings in energy density and stability mainly highlight on the increase in internal resistance and electrode polarization at subzero temperatures, which greatly affect the reversible capacities of lithium‐ion batteries. In this work, a conversion type Co3O4@graphene (Co3O4@G) composite is prepared via a simple hydrothermal method and first evaluated at subzero temperatures. Benefitting from the especially suitable lithiation/delithiation potentials of Co3O4, ingenious nanostructure and high conductivity of graphene, the Co3O4@G anode exhibits much higher capacity retentions than intercalation‐ and alloying‐type anodes at subzero temperatures, with 58.4% of room‐temperature capacity retention at −30 °C for initial cycle and a highly stable reversible capacity of 605.0 mAh g−1 (0.5 A g−1) for 600 cycles at −10 °C. Furthermore, very high capacities of ∼920.4 mAh g−1 (0.2 A g−1) can be maintained at 30 °C, and ∼450.2 mAh g−1 (0.5 A g−1) can be remained at −20 °C during alternating cycling. This work demonstrates that conversion‐type Co3O4@G composites have superior extreme temperature lithium storage capabilities and can be viable Li‐ion anode materials with fast and highly efficient ion/electron transport capacity at subzero operating temperatures.