Advanced Lithium-ion Battery Anode Research Articles

Leaf-shaped bimetallic sulfides@N-doped porous carbon as advanced lithium-ion battery anode

Transition metal sulfides have attracted wide attention in energy storage, especially in Li-ion batteries anodes due to the high theoretical capacity and low cost. However, their poor stability and rate performance have hindered their further development. Here, leaf-shaped ZIF (zeolitic imidazole framework) was used as precursor to prepare two-dimensional (2D) CoZnSx@N-doped Carbon (L-Co2Zn1-S) to address this problem. The different distribution of Zn2+ and Co2+ will greatly influence the morphology of products. L-Co2Zn1-S displays great cycling performance of specific capacity of 527 mA h g−1 at 0.5 A g−1 after 200 cycles with Coulombic efficiency of about 99% and excellent rate capability as lithium-ion battery anode. This superior electrochemical performance can be ascribed to 2D N-doped carbon structure and synergistic effect of bimetallic sulfide. This work not only casts a new light on the design of bimetallic sulfides but also provides a manufacturing method of 2D carbon matrix.

Fabricating thin two-dimensional hollow tin dioxide/carbon nanocomposite for high-performance lithium-ion battery anode

Both thin two-dimensional (2D) and hollow nanostructural materials are of great potential for high-performance anodes of lithium-ion batteries owing to their unique structural properties and surface characteristics. In this context, tin dioxide (SnO2) materials possessing well-designed thin 2D or hollow nanostructures have attracted immense attention and been considered as promising candidates to serve as anodes for advanced lithium-ion batteries. It is believed that thin 2D hollow nanostructures of SnO2 materials will have the advantages of both thin 2D and hollow nanostructures but they are difficult to be prepared due to the increased complexity of structures. Herein, a peculiar thin 2D hollow nanostructure of SnO2/carbon (SnO2/C) composite, composed of carbon in-situ coating thin SnO2 hollow nanosheets, has been prepared through a well-designed strategy. It is thus clear that this composite possesses the advantages of both thin 2D and hollow nanostructures as an anode for lithium-ion batteries. Expectedly, it is demonstrated that thus peculiar architecture offers the as-prepared SnO2/C composite superior electrochemical kinetics and outstanding structural stability. As a result, the as-prepared SnO2/C composite exhibits outstanding electrochemical lithium storage performance, delivering 707.8 and 483.2 mAh g−1 after 100 cycles at 200 and 1000 mA g−1, respectively, as well as superior rate capabilities.

Surface-Bound Silicon Nanoparticles with a Planar-Oriented N-Type Polymer for Cycle-Stable Li-Ion Battery Anode.

Silicon is now well-recognized to be a promising alternative anode for advanced lithium-ion batteries because of its highest capacity available today; however, its insufficiently high Coulombic efficiency upon cycling remains a major challenge for practical application. To overcome this challenge, we have developed a facile mechanochemical method to synthesize a core-shell-structured Si/polyphenylene composite (Si/PPP) with a n-type conductive PPP layer tightly bonded in a planar orientation to the surfaces of Si nanocores. Because of its compactness and flexibility, the outer PPP layer can protect the Si core from contacting the electrolyte and maintaining the structural stability of electrode/electrolyte interface during cycles. As a result, the Si/PPP anode demonstrated a high reversible capacity of ∼2387 mAh g-1, a stable cycleability with 88.5% capacity retention over 500 cycles, and, particularly, a high Coulombic efficiency of 99.7% upon extended cycling, offering a new insight for future development of high-capacity and cycle-stable Si anode.

(Invited) Swelling of Si Nano-Flake Anode for Advanced Lithium-Ion Batteries

The poor cyclability of Si electrodes is attributed to crack formation and pulverization of Si active material due to a large volume expansion and contraction during charging and discharging, respectively. It is thus important to suppress the physical stress induced by the large volume changes to improve the cyclability of Si electrodes. We designed a Si powder with a flake shape (Si LeafPowderÒ, Si-LP, OIKE & Co., LTD.) with 100 nm in thickness and 3-5 mm in lateral dimension, and have reported that Si-LP electrodes have a high initial discharge capacity (ca. 2,500 mAh g-1) and good cycleability (Fig. 1) [1]. Another serious problem of Si anode is a swelling of the electrode owing to irreversible microstructural changes of Si nano-flakes upon cycling (Fig. 2). The Si-LP sheets in a composite electrode were substantially deformed during alloying/de-alloying cycling and formed the multi-folded layered structure on repeated cycling. Furthermore, many voids, which could accommodate volume changes of Si, were formed on repeated cycling. The multi-folded layered structure with many voids enabled the stable battery operation of the Si-LP electrodes. On the other hand, the thickness of the electrode remarkably increased with cycle number (Fig. 3), which was caused by the deformation of Si-LP sheets and growth of the SEI layer. The electrode swelling was suppressed by the presence of the additives, VC and FEC. The uniform SEI layer formed from the decomposition products of VC or FEC inhibited further decomposition of the electrolyte and suppressed the deformation of the Si-LP sheets. Unfortunately the suppression of the electrode swelling by the additives is not enough, and further suppression of the electrode swelling and/or a new cell design to manage the large volume changes of Si is necessary for practical applications of the Si-LP as a negative electrode in advanced LIBs. This research was supported by Japan Science and Technology Agency (JST) ALCA-SPRING and Japan Society for the Promotion of Science (JSPS) KAKENHI Grant Number 16H04649.

Coaxial-cable hierarchical tubular MnO2@Fe3O4@C heterostructures as advanced anodes for lithium-ion batteries

Nanostructured manganese oxides have been regarded as promising anodes for lithium-ion batteries (LIBs) due to their high specific capacity, environmental friendliness and low cost. However, as conversion-type electrodes, their scalable utilization is hindered by intrinsically low reaction kinetics, large volume variation and high polarization. Herein, a coaxial-cable tubular heterostructure composed of a hollow carbon skeleton, Fe3O4 nanoparticles and ultrathin MnO2 nanosheets from inside out, donated as MnO2@Fe3O4@C, is synthesized via a facile two-step hydrothermal process. The unique design integrates conductive carbon and nanostructured MnO2 and Fe3O4 into a one-dimensional (1D) hierarchically open architecture, which provides abundant electrode–electrolyte contact areas, favorable heterointerfaces and ultrafast electron/ion pathways. Benefiting from these features, the MnO2@Fe3O4@C anode exhibits a high reversible capacity of 946 mAh g−1 at 200 mA g−1 after 160 cycles, and excellent cyclability with a specific capacity of 845 mAh g−1 at 500 mA g−1 after 600 cycles. This work might provide an insightful guideline for the design of novel electrode materials.

Reviving bulky MoS2 as an advanced anode for lithium-ion batteries

The high intrinsic Li storage capacity of bulky MoS2 is readily released by a rationally designed composite with a 3D conductive carbon skeleton.

Modified SiO hierarchical structure materials with improved initial coulombic efficiency for advanced lithium-ion battery anodes.

Silicon-based anode materials are indispensable components in developing high energy density lithium-ion batteries, yet their practical application still faces great challenges, such as large volume change during the lithiation and delithiation process that causes the pulverization of silicon particles, and continuous formation and reformation of the solid electrolyte interfaces (SEI) which results in a low initial coulombic efficiency. As an endeavor to address these problems, in this study, Si/SiO/Li2SiO3@C structures were prepared via a facile method using SiO, pitch powder and Li2CO3/PVA solution followed by annealing treatment. The Si/SiO/Li2SiO3@C composite shows a great improvement in lithium storage where a high discharge capacity of 1645.47 mA h g−1 was delivered with the 1st C.E. of 69.05% at 100 mA g−1. These results indicate that the designed method of integrating prelithiation and carbon coating for SiO and the as-prepared macro scale Si/SiO/Li2SiO3@C structures are practical for implementation in lithium-ion battery technology.

A general approach for fabricating 3D MFe2O4 (M=Mn, Ni, Cu, Co)/graphitic carbon nitride covalently functionalized nitrogen-doped graphene nanocomposites as advanced anodes for lithium-ion batteries

Efficient energy storage systems based on rechargeable lithium-ion batteries (LIBs) represent the most leading technology in the field of portable devices market. Nanostructured electrode materials possess compelling opportunities for high-performance LIBs, but it's still the main challenge to ensure the structural integrity of the electrodes over harsh discharge-recharge cycles. Here, we present a general approach, combining self-assembly process, in-situ substitution, and thermal annealing, for the fabrication of a 3D heteroarchitecture built from nanosized spinel ferrites (MFO, denoted as MFe2O4, M = Mn, Ni, Cu, Co) and graphitic carbon nitride covalently functionalized nitrogen-doped graphene (CN-NG). This typical 3D architecture could possess a series of distinctive structural advantages, including: (i) sufficient hierarchical pores and channels for the rapid access of electrolytes, (ii) plentiful topological defects introduced by lamellar g-C3N4 nanoflakelets for the ultrafast absorption and diffusion of lithium ions, (iii) incorporation of structural nitrogen in graphene to modulate the electronic structure for boosting the electron transport and providing extra mechanism for lithium storage, (iv) uniformly distributed MFO nanoparticles with large amounts of active centers and high reversible capacities, (v) strong covalent C-N bonding and metal-support interaction for guaranteeing the long-term electrochemical cyclability, all of which are conducive to accelerating the improvement of lithium storage properties. As a consequence, significantly high reversible capacities of 1032, 919, 1008, and 1105 mAh g−1 are obtained for 3D MnFe2O4/CN-NG(0.4), 3D NiFe2O4/CN-NG(0.4), 3D CoFe2O4/CN-NG(0.4), and 3D CuFe2O4/CN-NG(0.4), respectively, at a current density of 0.1 A g−1. Especially, 3D MnFe2O4/CN-NG(0.4) presents a capacity retention of 73% at a high current density of 1 A g−1 even after 800 cycles, as well as excellent rate capability and reliable long-term cycling stability. It is anticipated that the synthetic strategy present here can be further extended to the construction of various 3D heteroatom-doped carbonaceous nanomaterials that contain metals or metal oxides, which offers new possibilities in the fabrication of advanced supports for maximum utilization, alleviating volume variation and the particle fracture of active materials in LIBs.

Ultrafine CuO nanoparticles decorated activated tube-like carbon as advanced anode for lithium-ion batteries

Recently, copper oxide (CuO) as promising anode material for lithium-ion batteries (LIBs) has received much interest. Hybridizing CuO with carbon is considered as a valid way to improve the conductivity and alleviate the volume effect of CuO, but how to achieve more optimized utilization rate of CuO-based anodes still remains a big challenge for us. In this work, activated tube-like carbon (ATC) is firstly prepared by pre-carbonization followed by alkali etching process using palm tree bark hair as initial carbon source, then the ATC is used as carbon matrix to load CuO by a modified phase-transfer approach. As a result, ultrafine CuO nanoparticles decorated ATC (ATC/CuO) can be obtained. For comparison, we also synthesize tube-like carbon (TC) by a direct pyrolysis process, and obtain TC/CuO hybrid by similar loading method. The morphology, structure, composition and surface property of the two carbon matrixes and the corresponding C/CuO hybrids are all systematically investigated. The results show that ATC/CuO hybrid possesses rich COCu bond and unique ultrafine CuO structure, which is attributed to the co-effect of abundant oxygen-containing groups, large specific surface area and special microporous property of ATC matrix. Consequently, the ATC/CuO electrode exhibited much enhanced cycling stability and rate capability when compared to sole CuO and TC/CuO electrodes. Obviously, our work provides a good guidance on the design and development of advanced carbon/metal oxide-based anodes for LIBs.

Co3S4@C@MoS2 microstructures fabricated from MOF template as advanced lithium-ion battery anode

Transition metal chalcogenides as a promising anode material with high theoretical capacity has attracted more and more attention. This thesis focuses on a facile method to synthesize hollow Co3O4 encapsulated by carbon layers (Co3O4@C) with polydopamine as precursor, after reacting with thioacetamide and (NH4)6Mo7O24·4H2O, hollow rhombic dodecahedral shape Co3S4@C@MoS2 heterostructures are successfully fabricated and employed as the anode of lithium-ion battery. Benefiting from the typical layered structure of Co3S4@C@MoS2 heterostructures, the stability and capacity have been significantly improved, with a high capacity of 672.6 mAh g−1 after 200 cycles at the current density of 0.2 A g−1. The excellent electrochemical properties of hollow Co3S4@C@MoS2 heterostructures are ascribed to the consolidate of Co3S4, carbon and MoS2, and the stability of the composite structure.

Multi-component hollow nanostructure endows tin dioxide with outstanding lithium storage performance

Herein, the huge volume variation and poor conductivity issues of SnO2 incurred are well addressed by fabrication of a TiO2@SnO2@C hollow nanosphere composite (TiO2@SnO2@C HS) with a satisfying synergistic effect of component and structure. As a result, the as-fabricated TiO2@SnO2@C HS presents excellent lithium storage performance, delivering high capacities of 937.5 and 605.7 mAh g−1 at 200 and 1000 mA g−1 after 250 and even 1000 cycles, respectively. The facile fabrication process and excellent lithium storage performance may make this TiO2@SnO2@C HS a promising candidate for advanced lithium-ion battery anode materials.

Folded-hand silicon/carbon three-dimensional networks as a binder-free advanced anode for high-performance lithium-ion batteries

Folded-hand silicon/carbon (Si/C) three-dimensional (3D) networks were fabricated by chemical vapor deposition coupled with ultrasonic atomization and successfully applied for a binder-free anode in lithium-ion batteries. The microstructure, morphology and electrochemical performance for Si/C 3D networks were investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and galvanostatic charge-discharge tests. The repeated folded-hand units for Si/C composites are assembled into interconnected 3D networks. The folded-hand Si/C 3D networks show an outstanding charge capacity of 2277 mAh g−1 at 0.1 C, and still remain 2167 mAh g−1 after 100 cycles. They reveal an excellent rate capacity of 1848 mAh g−1 and capacity retention of 99% after 100 cycles at 2 C, the charge capacities of 862 mAh g−1 and capacity retention of 93% after 500 cycles at 5 C. The LiFePO4//Si-C full cell can maintain high capacity of 137 mAh g−1 and capacity retention of 92% after 500 cycles at 1 C rate. The superior electrochemical performance is attributed to the formation of three-dimensional folded-hand interconnected networks.

Controllable in-situ growth of 3D villose TiO2 architectures on carbon textiles as flexible anode for advanced lithium-ion batteries

Controllable three-dimensional villose titanium dioxide architectures grown on carbon textiles are fabricated by a facile one-step in-situ hydrothermal method at low temperatures. It has in fact been proven to be an effective method to reduce self-aggregation and promote lithium-ion intercalate/extract via building 3D architectures based on 2D conductive materials. More importantly, the freestanding electrodes without any addition of conductive agents and polymeric binders reveal significant improvement in high-rate capacity and cycling performance.

FexP/C core-shell nanocubes with large inner void space for advanced lithium-ion battery anode

Iron-based phosphides are one good anode candidate for lithium ion batteries except the problem of low conductivity and large volume expansion. To get over these disadvantages, FexP/C core-shell nanocubes are synthesized by a simple approach without high temperature and direct use of toxic gas, involving Prussian Blue as the precursor and a low-temperature phosphidation process. Herein, the FexP/C nanocubes possess enough inner void space, which can accommodate the large volume expansion for internal FexP nanoparticles during Li+ intercalation and deintercalation process. And the carbon shell can enhance conductivity of electrodes, which is beneficial for transportation of Li+. All these advantages endow FexP/C with outstanding performance as anode materials for lithium-ion batteries. As a result, the obtained FexP/C core-shell nanocubes deliver a high reversible capacity of 665 mAh g−1 after 200 cycles at the current density of 100 mA g−1. This work supply one approach for controllable synthesis of metal phosphides for lithium-ion batteries, hydrogen evolution reaction, catalysis, etc.

Hierarchical porous CoMn2O4 microspheres with sub-nanoparticles as advanced anode for high-performance lithium-ion batteries

To deal with the large volume change for lithium-ion batteries (LIBs), we illustrate the synthesis of CoMn2O4 microspheres with sub-nanoparticles by a hydrothermal method followed by thermal treatment. The size of microsphere is approximately 2.2 μm, and the sub-nanoparticle is about 17 nm. There is sufficient void space between CoMn2O4 microspheres with sub-nanoparticles for ensuring the well structural integrity. As advanced anode for LIBs, CoMn2O4 microspheres display stable specific capacity retention of 772 mAh g−1 over 500 cycles at a current density of 100 mA g−1. Such a kind of structure is beneficial for enhanced rate and cycling capabilities in LIBs applications, which could increase contact area between electrolyte and active materials, short path for lithium ions and electrons and accommodate the volume change with additional void space during cycling. It has a great application prospect for use as electrochemical energy storage because of the enhanced performance.

Bouquet-Like Mn2SnO4 Nanocomposite Engineered with Graphene Sheets as an Advanced Lithium-Ion Battery Anode.

Volume expansion is a major challenge associated with tin oxide (SnO x), which causes poor cyclability in lithium-ion battery anode. Bare tin dioxide (SnO2), tin dioxide with graphene sheets (SnO2@GS), and bouquet-like nanocomposite structure (Mn2SnO4@GS) are prepared via hydrothermal method followed by annealing. The obtained composite material presents a bouquet structure containing manganese and tin oxide nanoparticle network with graphene sheets. Benefiting from this porous nanostructure, in which graphene sheets provide high electronic pathways to enhance the electronic conductivity, uniformly distributed particles offer accelerated kinetic reaction with lithium ion and reduced volume deviation in the tin dioxide (SnO2) particle during charge-discharge testing. As a consequence, ternary composite Mn2SnO4@GS showed a high rate performance and outstanding cyclability of anode material for lithium-ion batteries. The electrode achieved a specific capacity of about 1070 mA h g-1 at a current density of 400 mA g-1 after 200 cycles; meanwhile, the electrode still delivered a specific capacity of about 455 mA h g-1 at a high current density of 2500 mA g-1. Ternary Mn2SnO4@GS material could facilitate fabrication of unique structure and conductive network as advanced lithium-ion battery.

In-Situ Synthesis of Sn/SnO2@C Composites for Lithium and Sodium-Ion Batteries

Tin oxide (SnO2) is considered as a promising material for both Li- and Na-ion batteries due to its high theoretical capacities (1494 mAh/g with Li and 1378 mAh/g with Na; 2~3 times higher than common carbon-based anode)1-3. However, the initial irreversible capacity loss induced by inactive Li2O/Na2O formation and volume change (260% with Li and 420% with Na) during charge/discharge process need to be addressed in order to improve cycling performance4. In addition, the poor electronic conductivity of above mentioned alkali metal oxides and gradual aggregation of Sn particles in the electrode structure during operation lead to poor rate capability and rapid capacity fading. Many studies have strived to address these issues and result in the development of diverse types of SnO2-based nanocomposites with carbonaceous materials including reduced graphene oxides5-7, carbon nanofibers8,9, carbon nanotubes10,11, and disordered carbons12,13 to enhance initial coulombic efficiency and electronic conductivity in the electrode structure as well as to prohibit Sn particle aggregation by introducing physical barriers between active materials. However, the cycling performance and initial irreversible capacity loss of the currently reported composites still remain insufficient to be adopted in practical cells. In this work, carbon-coated porous Sn/SnO2 composite (Sn/SnO2@C) is synthesized via inorganic CO2 reduction route with magnesium stannide (Mg2Sn) for Li- and Na-ion batteries. High purity Mg2Sn powder is prepared by solid-state reaction and then thermally treated under CO2 flow environment. During the second heat treatment, gaseous CO2 molecules becomes reduced down to elemental C via interaction with Mg which is known to be highly reductive in nature (Mg2Sn + CO2 à 2MgO + Sn + C, ΔG = -690 kJ/mol). The resultant Sn is partially oxidized to form SnO2 which eventually results in Sn/SnO2@C composite. Electrodes with this composition and structure exhibit enhanced initial coulombic efficiency and stable cycling performance. It appears that a nanocomposite matrix in which active materials are distributed without aggregation in intimate contact with C is essential for realizing SnO2-based anodes for Li- and Na-ion batteries with long cycle life. 1 Lee, J.-I. et al. Multifunctional SnO2/3D graphene hybrid materials for sodium-ion and lithium-ion batteries with excellent rate capability and long cycle life. Nano Research, doi:10.1007/s12274-017-1756-3 (2017). 2 Kim, Y., Yoon, Y. & Shin, D. Fabrication of Sn/SnO2 composite powder for anode of lithium ion battery by aerosol flame deposition. Journal of Analytical and Applied Pyrolysis 85, 557-560, doi:https://doi.org/10.1016/j.jaap.2008.06.005 (2009). 3 Lee, Y. et al. Hollow Sn–SnO2 Nanocrystal/Graphite Composites and Their Lithium Storage Properties. ACS Applied Materials & Interfaces 4, 3459-3464, doi:10.1021/am3005237 (2012). 4 Sivashanmugam, A. et al. Electrochemical behavior of Sn/SnO2 mixtures for use as anode in lithium rechargeable batteries. Journal of Power Sources 144, 197-203, doi:https://doi.org/10.1016/j.jpowsour.2004.12.047 (2005). 5 Hu, X., Zeng, G., Chen, J., Lu, C. & Wen, Z. 3D graphene network encapsulating SnO2 hollow spheres as a high-performance anode material for lithium-ion batteries. Journal of Materials Chemistry A 5, 4535-4542, doi:10.1039/C6TA10301D (2017). 6 Fan, L. et al. Controlled SnO2 Crystallinity Effectively Dominating Sodium Storage Performance. Advanced Energy Materials 6, 1502057-n/a, doi:10.1002/aenm.201502057 (2016). 7 Tian, R. et al. The effect of annealing on a 3D SnO2/graphene foam as an advanced lithium-ion battery anode. Scientific Reports 6, 19195, doi:10.1038/srep19195 https://www.nature.com/articles/srep19195#supplementary-information (2016). 8 Wang, M., Li, S., Zhang, Y. & Huang, J. Hierarchical SnO2/Carbon Nanofibrous Composite Derived from Cellulose Substance as Anode Material for Lithium-Ion Batteries. Chemistry – A European Journal 21, 16195-16202, doi:10.1002/chem.201502833 (2015). 9 Liu, Y. et al. Enhanced electrochemical performance of hybrid SnO2@MOx (M = Ni, Co, Mn) core-shell nanostructures grown on flexible carbon fibers as the supercapacitor electrode materials. Journal of Materials Chemistry A 3, 3676-3682, doi:10.1039/C4TA06339B (2015). 10 Cui, J. et al. Enhanced conversion reaction kinetics in low crystallinity SnO2/CNT anodes for Na-ion batteries. Journal of Materials Chemistry A 4, 10964-10973, doi:10.1039/C6TA03541H (2016). 11 Chen, S. et al. Branched CNT@SnO2 nanorods@carbon hierarchical heterostructures for lithium ion batteries with high reversibility and rate capability. Journal of Materials Chemistry A 2, 15582-15589, doi:10.1039/C4TA03218G (2014). 12 Fan, J. et al. Ordered, Nanostructured Tin-Based Oxides/Carbon Composite as the Negative-Electrode Material for Lithium-Ion Batteries. Advanced Materials 16, 1432-1436, doi:10.1002/adma.200400106 (2004). 13 Pol, V. G., Wen, J., Miller, D. J. & Thackeray, M. M. Sonochemical Deposition of Sn, SnO2 and Sb on Spherical Hard Carbon Electrodes for Li-Ion Batteries. Journal of The Electrochemical Society 161, A777-A782, doi:10.1149/2.064405jes (2014).

Synergistically enhanced lithium storage performance based on titanium carbide nanosheets (MXene) backbone and SnO2 quantum dots

Titanium carbide MXene (Ti3C2Tx) possesses a metallic conductivity and an opened nanostructure, being an ideal host for transition metal oxide (TMO) to construct advanced lithium-ion battery anodes. However, Ti3C2Tx is prone to be oxidized under hydrothermal treatment, which limits the growth of TMO/MXene composites through a wet-chemistry approach. Here, we take advantage of the strong electrostatic interaction between SnO2 quantum dots (QDs) and delaminated Ti3C2Tx to protect the latter from oxidation under the hydrothermal condition. The in-situ heterogeneously nucleated SnO2 QDs are tightly anchored on the Ti3C2Tx nanosheets, while the Ti3C2Tx nanosheets effectively limit the growth/aggregation of SnO2. Further freeze-drying of the colloidal mixture results in the SnO2 QDs@Ti3C2Tx composite with conductive Ti3C2Tx nanosheets as backbone, which displays a high specific surface area and abundant voids. The unique architecture design renders SnO2 QDs@Ti3C2Tx a high capacity (1021 mAh g−1 at 100 mA g−1 in the 2.6 mg cm−2 electrode) and long lifetime performance, which maintains 810 mAh g−1 after 200 cycles (100 mA g−1), 697 mAh g−1 after 520 cycles (200 mA g−1) and 500 mAh g−1 after 700 cycles (at 500 mA g−1). More importantly, this wet-chemistry/freeze-drying approach is general, and can be extended to other TMOs and MXenes to fabricate corresponding TMO QDs/MXene composites for various applications.

Carbon shelled porous SnO2-δ nanosheet arrays as advanced anodes for lithium-ion batteries

Although SnO2 is theoretically a high capacity anode material for lithium-ion batteries, it suffers from poor cycle performance and poor rate capability due to structural instability and sluggish electrode kinetics. To mitigate these problems, here, an oxygen-deficient SnO2-δ/C composite with rationally designed nanoarchitecure comprising carbon shelled porous SnO2-δ nanosheet arrays is prepared as anode for lithium-ion batteries. It is found that crystalline and amorphous domains coexist in the SnO2-δ phase, which is beneficial for improved structural stability and enhanced Li+ diffusion. The as-prepared porous SnO2-δ/C nanosheet arrays can deliver a large reversible specific capacity of 1378.6 mA h g−1 with a high initial Coulombic efficiency of about 74.3% at a current density of 0.1 A g−1. In addition to large reversible capacity, the porous SnO2-δ/C nanosheet arrays also exhibit superior rate performance and cycle performance, outperforming those of SnO2, porous SnO2, and SnO2-δ/C nanosheet arrays, demonstrating robust structural stability, high reversibility, and fast charge transport for the rational nanoarchitecture design. Finally, a full cell consisting of porous SnO2-δ/C nanosheet arrays as anode and LiMn2O4 nanosheet arrays as cathode is constructed and exhibits promising battery performance, demonstrating the potential application of porous SnO2-δ/C nanosheet arrays in high-performance lithium-ion batteries.

3D composites of ZnSnO3 nanoplates/reduced graphene oxide aerogels as an advanced lithium-ion battery anode

Zinc-based bimetal oxides have received considerable attention as anode for lithium-ion batteries (LIBs). A one-pot self-assembly hydrothermal method is developed for the fabrication of 3D hierarchical structure aerogels from zinc stannate (ZnSnO3) and reduced graphene oxide (rGO). 3D interconnected porous structure with ZnSnO3 hexagon nanoplates uniformly dispersed on graphene sheets has been constructed successfully, in which the crystalline hexagon nanoplates ZnSnO3 are firstly used to prepare ZnSnO3-based anode materials for LIBs. The as-prepared ZnSnO3 nanoplates/reduced graphene oxide aerogels (ZnSnO3–rGAs) electrode demonstrates an excellent reversible capacity (780 mAh g−1) after 200 cycles at a certain current density (100 mA g−1) and still delivers a specific capacity of 460 mAh g−1 even at 1000 mA g−1. The superior performance of lithium storage is attributed to the 3D porous hierarchical structure and the synergistic effects of uniform hexagon nanoplates ZnSnO3 and rGO sheets.