Lithium-ion Half Research Articles

Hierarchical Electrode Constructed by carbon-coated Metal-Organic Framework Derivatives Supported on two-dimensional Ti3C2 nanosheets for Hybrid Li-ion Capacitors

BackgroudMetal-organic frameworks (MOFs) (e.g., Co-MOF) had been a popular platform for synthesis electrode materials for lithium-ion capacitors (LICs) because of their high theoretical specific capacity and unique structural advantages. Recent researches have focused on the development of MOFs derivative-based composites with high specific surface area, high structural stability, and high electrical conductivity. Methods: Here a distinct Ti3C2/Co3O4@C heterostructure composite was prepared by a straightforward method via hydrogen bonding with carbon-coated Co-MOF derivative anchored on Mxene-Ti3C2 nanosheets. The carbon-coated hollow Co3O4 polyhedra could shorten Li+ diffusion paths, increase the specific surface area and mitigate structural changes during the Li+ storage process. Moreover, Ti3C2 sheets were acted as a conductive network, which could increase the Li+ transport rate and stability of the structure. SignificantServing as anode material, Ti3C2/Co3O4@C electrode showed a specific capacity of 1341 mAh/g at current density of 0.1 A/g, with 93% capacity maintenance at 2 A/g after 1000 cycles in the lithium-ion half cell. Furthermore, Ti3C2/Co3O4@C//AC LIC delivered a high energy of 106 Wh/kg at 7632 W/kg. The distinct heterostructure, straightforward, and excellent performance of the Ti3C2/Co3O4@C composite as anode could provide application prospects in LICs with high energy/power density.

Rapid and Reversible Lithium Insertion with Multielectron Redox in the Wadsley-Roth Compound NaNb13O33

The development of high-performing battery materials is critical to meet the ever-increasing demand for portable energy storage for electronics and electric vehicles. Owing to their exceptionally high-rate capabilities, high volumetric capacities and long lifetimes, Wadsley-Roth compounds are promising lithium anode materials for fast-charging and high-powered devices. This study comprises an in-depth structural and initial electrochemical investigation of the Wadsley-Roth phase NaNb13O33 phase. To our knowledge, this is the first alkali-containing Wadsley-Roth compound tested for lithium insertion.Here, we report structural insights obtained from combined neutron and synchrotron diffraction as well as solid-state nuclear magnetic resonance (ss-NMR). We find that a variety of simple, solid-state methods reliably produce a ReO6-like base structure with periodic, ”shear” planes of edge-sharing NbO6 octahedra separating 5 x 3 octahedral blocks with square-planar Na+ occupying block corners. Through ss-NMR, we reveal the presence of sodium cations in block interior sites as well as square-planar block sites.Through combined experimental and computational studies, we demonstrate and rationalize the high-rate performance of this new anode material in lithium-ion half cells. Using X-ray photoelectron spectroscopy (XPS), we show the multi-electron redox of Nb, which enables capacities of 225 mA h g−1 at slow rates and anodic potentials. Without down-sizing or nano-scaling, 100 mA h g−1 of this capacity is retained at 20 C in micrometer-scale particles. By combining bond-valence mapping and DFT, we show that such excellent rate performance results from facile, multi-channel lithium diffusion down octahedral block interiors and from high electronic conductivity within shear planes. Finally, we utilize differential capacity analysis to identify optimal long-term cycling rates and achieve 80% capacity retention over 600 cycles with 30-minute charging and discharging intervals.Without optimization, these results place NaNb13O33 in the ranks of promising new high-rate lithium anode materials and warrant further research.

A synergic effect of N-Graphene wrapped [formula omitted]-Fe[formula omitted]O[formula omitted] nanofacets prepared by Microwave-assisted solvothermal method for Lithium-ion battery

α-Fe2O3 nanofacets have been synthesized by the microwave-assisted solvothermal method. The nitrogen-doped reduced Graphene oxide (N-Graphene) was synthesized using Hummer’s method. The prepared Fe2O3 and N-Graphene were mixed under certain proportions using a microwave treatment process to prepare a novel N-Graphene wrapped α-Fe2O3 nanofacets. The synthesized samples were analyzed using X-ray Diffraction, Raman spectroscopy, Semi Macro Elemental (CHNS-OX) Analyzer, Scanning Electron Microscopy, Transmission Electron Microscopy and X-ray Photoelectron Spectroscopy for identifying crystal structure and phase, the morphology of the nanostructure and the elemental configuration, respectively. The prepared N-Graphene wrapped α-Fe2O3 nanofacets were used as anode material and lithium metal as a counter electrode to fabricate half cell using Swagelok type lithium ion half cells. The electrochemical properties were studied and exhibited a large specific capacity of 878mAhg−1 after 100 cycles measured under 100mAg−1 current rate due to the synergic effect of N-Graphene and Fe2O3 nanofacets. The obtained capacity values are higher than the conventional Graphite as anode material due to the synergic effect on the properties of N-Graphene and α-Fe2O3 nanofacets and would be a promising potential candidate for the electrochemical devices.

Hierarchical architecture of two-dimensional Ti3C2 nanosheets@Metal-Organic framework derivatives as anode for hybrid li-ion capacitors

Two-dimensional (2D) layered metal carbides materials called MXenes (e.g., Ti3C2) are significantly attentioned as electrode material for lithium-ion capacitors (LICs) because of its large surface-to-volume ratio and ultra-high electronic conductivity. Whereas, as anode electrode material, the performance and application prospects of Ti3C2 are severely restricted to its lower theoretical capacity. In this work, a straightforward and effective strategy to surmount the restrictions was developed to combine layered Ti3C2 nanosheets with dual Co/Zn metal–organic framework (MOF) polyhedrons derivatives through electrostatic assembly. Co3O4/ZnO polyhedrons could prevent the stacking of Ti3C2 nanosheets and provide prominent lithium storage capacity. Furthermore, the advanced structure of Ti3C2@Co3O4/ZnO as anode material could provide short Li+ paths, large electrolyte channels and excellent structural stability to enhance the electrochemical performance for LICs. As a result, the prepared Ti3C2@Co3O4/ZnO composite exhibited a specific capacity of 585.7 mAh/g at 0.1 A/g, and the electrode still delivered a capacity of 229 mAh/g at 2 A/g after 1000 cycles with 93% capacity retention in lithium-ion half cell. In addition, by assembling with activated carbon (AC) as cathode and Ti3C2@Co3O4/ZnO as anode, the LIC revealed an ultra-high energy density of 196.8 Wh/kg at a power density of 174.9 W/kg, and delivered a high energy output of 87.5 Wh/kg even at a power density of 3500 W/kg. And its capacitance retention reaches 75% after 6000 cycles at 2 A/g. The advanced structure, handy preparation, and outstanding performance of layered carbon-based material Ti3C2@hollow polyhedrons composite might provide promising applications in LICs.

Remarkably improved cycling stability of 3D porous Cu–Sn anode for lithium-ion full cells by adjusting working voltage range

Numerous studies confirm that three dimensional porous Cu–Sn (3DP Cu–Sn) anode possesses good application prospect in light of its desirable electrochemical performance on lithium ion half cells, but there are a few related systematic researches on lithium ion full cells until now, which is indispensable before its commercialization. Herein, the effects of galvanostatic charge-discharge voltage range on the cycling stability of 3DP Cu–Sn anode for lithium ion full cells are investigated systematically. The results show that the suitable charge-discharge voltage range plays a key role in improving the reversible capacity and cycling stability of the 3DP Cu–Sn||LiCoO2 full cell, which is closely related to maintaining the electrode structure stable by controlling the amount of Li+ extracted and inserted. Especially, in the voltage range of 1.2–3.9 ​V, the full cell exhibits remarkably improved electrochemical properties with the high initial reversible capacity of 2.71 ​mAh cm−2 and 71.95% capacity retention upon 80 cycles. We believe that this work can provide a significant reference for the practical application of porous Sn-based anodes.

Iron Phosphide Confined in Carbon Nanofibers as a Free-Standing Flexible Anode for High-Performance Lithium-Ion Batteries.

Iron phosphide with high specific capacity has emerged as an appealing candidate for next-generation lithium-ion battery anodes. However, iron phosphide could undergo conversion reactions and generally suffer from a rapid capacity degradation upon cycling due to its structure pulverization. Chemomechanical breakdown of iron phosphide due to its rigidity has been a challenge to fully realizing its electrochemical performance. To address this challenge, we report here on an enticing opportunity: a flexible, free-standing iron phosphide anode with Fe2P nanoparticles confined in carbon nanofibers may overcome existing challenges. For the synthesis, we introduce a facile electrospinning strategy that enables in situ formation of Fe2P within a carbon matrix. Such a carbon matrix can effectively minimize the structure change of Fe2P particles and protect them from pulverization, allowing the electrodes to retain a free-standing structure after long-term cycling. The produced electrodes showed excellent electrochemical performance in lithium-ion half and full cells, as well as in flexible pouch cells. These results demonstrate the successful development of iron phosphide materials toward high capacity, light weight, and flexible energy storage.

Electrophoretic deposition of nickel ferrite anode for lithium-ion half cell with superior rate performance

We report the use of nickel ferrite (NFO) with different morphologies as a superior anode material for lithium-ion batteries. The NFO nanoparticles are synthesized using simple auto-combustion process (CNFO) and micron-sized faceted particles are synthesized through pyrolysis of a nickel and iron metal-organic framework (MOF-NFO). Facile electrophoretic deposition (EPD) technique is employed to fabricate electrodes from a stable suspension of the active material (NFO) and conducting carbon-black. The EPD grown electrodes are uniform, porous and well adhered to the copper current collector. The CNFO and MOF-NFO electrodes retain a reversible capacity of 560 and 650 mAhg−1, respectively, after 150 cycles at a specific current of 0.5 Ag−1. Such EPD grown electrodes exhibit excellent rate capability delivering a capacity of 150 and 275 mAhg−1 at a high specific current of 8 Ag−1 for CNFO and NFO-MOF electrodes, respectively. The role of pseudocapacitance in enhancing the rate performance has been explained with the help of electrochemical impedance spectroscopy (EIS) and cyclic voltammetry. It is observed that even with significantly different particle size and morphology, the method of electrode fabrication plays a key role in accommodating the large volumetric changes during cycling and thereby improves the electrochemical properties of the electrode.

Operando Measurements of Electrolyte Lithium Ion Concentration during Fast-Charging

The ability to charge a Li-ion battery at high charging rates is critical for widespread electric vehicle adoption, but fast-charging rates can cause battery degradation and performance issues. A primary challenge for fast charging is finding electrolytes with sufficient lithium ion transport to operating under high current densities. However, there are few options for measuring ion transport in operating batteries. A novel diagnostic using Fourier transform infrared spectroscopy (FTIR) with attenuated total reflection (ATR) is reported for operando measurements of lithium ion concentration in a liquid electrolyte during battery operation. This diagnostic uses solvation shifting of solvent molecule vibrational modes to quantify lithium concentration. The diagnostic was calibrated using EC/EMC/LiPF6 electrolytes with known lithium concentrations from 0.03 mol/liter to 1.83 mol/liter. The concentration of PF6 - was also determined with a similar procedure. The resulting diagnostic can measure lithium concentrations from 0.001 to over 2 mol/liter with a minimum detection limit of 0.0011 moles/liter. The diagnostic is demonstrated using a lithium-ion half cell with a graphite anode and EC/EMC/LiPF6 electrolyte assembled in an argon-filled glove box. Measurements on the current collector side of the anode showed that as charging rates increased (i.e. during lithiation), lithium ion concentrations in the adjacent electrolyte decreased. The reverse trend was observed upon delithiation. These results demonstrate the utility of this diagnostic in quantifying ion depletion in electrolytes under fast charge conditions.

Spherical-graphite/nano-Mn2O3 composites as advanced anode materials for lithium half/full batteries

The spherical-graphite/Mn2O3 composites (SG/Mn2O3) with a core-shell structure have been facilely synthesized by the initial coprecipitation method and subsequent calcination treatment. As-synthesized composites as anode materials demonstrate remarkable lithium storage performances. The optimal SG/Mn2O3 with 17.6 wt% of Mn2O3 nanoparticles manifests the charge capacity of 499 mA h g−1 over 100 cycles at 0.5 A g−1, and presents the reversible capacity of 383 mA h g−1 under 2 A g−1 after 1000 long cycles for lithium-ion half batteries. When the optimal SG/Mn2O3 electrode is assembled to full-cell using LiFePO4 as the cathode, the full-cell affords the discharge capacity of 318 mA h g−1 with capacity retention of 97.2% at 0.1 A g−1 over 30 cycles. The high capacity of Mn2O3 nanoparticles coating on the surface/interface of SG enhances the long-periodic cycling properties and rate performance of overall electrode. The superior lithium storage performance demonstrates that the SG/Mn2O3 has great potential in the new-generation energy storage devices.

A stress-based charging protocol for silicon anode in lithium-ion battery: Theoretical and experimental studies

Abstract The large mechanical deformation induced by the lithiation/delithiation of silicon can induce rapid capacity fading of silicon-based lithium-ion battery. This work is focused on the development of a feasible stress-based charging protocol that can control the stress and deformation of silicon anode during electrochemical cycling from the stress analysis in a silicon particle. The stress-based charging protocol provides an approach to suppress the mechanical stress in silicon anode with the control of the upper cut-off voltage for delithiation. The numerical results reveal that applying a small upper cut-off voltage for delithiation can reduce the mechanical stress and lower the capacity of the silicon electrode, while it likely improves the performance of the silicon-based lithium-ion battery. Experimental study of silicon-based lithium-ion half cells reveals that applying a moderate cut-off voltage (600 mV in this work) achieves high reversible capacity and good cycling performance for all the C-rates tested in the work, and applying a large cut-off voltage of 1000 mV leads to the formation of large surface cracks and rapid capacity loss. The experimental results support the stress-based charging protocol, which is developed from the numerical analysis, that tuning the cut-off voltage can reduce the structural degradation and enhance the electrochemical performances of silicon-based lithium-ion battery.

Three-Dimensional Polypyrrole Nano-Network with Sb Nanocrystals as Electrode Material for Sodium-Ion and Lithium-Ion Batteries

In this work, we develop an approach to synthesize a nanoscale structure with Sb nanocrystals and polypyrrole nano-network (Sb@ppy NNW) from the reduction of SbCl3 and the polymerization and crosslinking of pyrrole. The Sb@ppy NNW exhibits excellent electrochemical characteristics with incessant conduction paths for fast transfer of electrons, short paths for fast diffusion/migration of ions and large contact area between active material and electrolyte for the storage of Na/Li. The Sb@ppy NNW is used as active material in the working electrode for lithium-ion half cells and sodium-ion half cells. The sodium-ion half cells possess excellent cycling stability with a high specific capacity of 510 mA h g−1 at a current density of 100 mA g−1 and 463 mA h g−1 after 100 cycles at a current density of 500 mA g−1, and superior rate performance with a specific capacity of 635.6 mA h g−1 even at a current density of 1600 mA g−1. The specific capacities for the lithium-ion half cells are 660 mA h g−1 after 100 cycles at a current density of 100 mA g−1 and 635.6 mA h g−1 even at a current density of 1600 mA g−1.

Hollow germanium nanocrystals on reduced graphene oxide for superior stable lithium-ion half cell and germanium (lithiated)-sulfur battery

Lithium-sulfur batteries are very promising due to low cost and high energy density compared to the current commercial lithium-ion batteries. However, when the anode is selected from lithium metal, it exhibits strong chemical activity since the electrolyte using an organic system and is liable to form lithium dendrites, leading to short lifespan and serious safety hazards. Here, we successfully synthesized the hollow germanium (and sulfur) nanocrystals tightly loaded on graphene nanosheets (Ge-HS/GNs and S-HS/GNs) architecture, and developed a novel configured lithiated germanium-sulfur battery by using lithiated Ge-HS/GNs as anode and S-HS/GNs as cathode. It is worth noting that the full battery displayed a high specific capacity of 586 ​mA ​h ​g−1 and energy density of 1025 ​W ​h ​kg−1 at 0.8 ​A ​g−1, outstanding rate performance (>400 ​mA ​h ​g−1 under 16 ​A ​g−1) and maintain a superior cycling stability over 500 cycles under 0.8 ​A ​g−1 (ultraslow capacity loss of 0.015% per cycle). This work provides an effective route towards high-energy rechargeable battery for advanced energy storage.

Few-layer NbSe2@graphene heterostructures as anodes in lithium-ion half- and full-cell batteries

A few-layered NbSe2@graphene (FLNG) composite is synthesized via wet ball-milling (WBM) as a new promising anode (wet ball-milled NbSe2@graphene or WBMNG) in lithium-ion half- and full-cell batteries. In this study, we first demonstrate that few-layered graphene (FLG) with low defect density can be prepared from bulk graphite via ball-milling in ethanol. Extending this concept, NbSe2 is introduced as a new 2D additive in WBM to produce a well-defined FLNG composite. FLNG contains NbSe2 particles (~200 nm lateral size and ~7.7 nm thickness (~37 layers)) embedded on a larger FLG (~1 μm lateral size and ~1.7 nm thickness (~5 layers)). The formation of FLNG is based on the solid lubrication in the WBM process that facilitates the exfoliation of 2D materials (NbSe2 and graphite), which leads to the increased surface area, enhanced electrical conductivity, and homogeneous mixing. When applied as an anode in a lithium-ion battery, FLNG (or WBMNG) exhibits excellent electrochemical performances in both WBMNG//Li half-cell and WBMNG//LiFePO4@graphite full-cell batteries. The half-cell displays a reversible discharge capacity as high as ~1000 mAh g−1 (capacity retention of ~88% compared with the initial capacity) at 0.1 A g−1 after 200 cycles and ~700 mAh g−1 at 1 A g−1 after 1000 cycles, with an excellent rate capability (~76% capacity retention at 10 A g−1 compared to the capacity at 0.1 A g−1). Moreover, the practical full-cell delivers a high energy density of ~216 Wh kg−1 after 100 cycles with excellent rate capability.

Au nanocrystals decorated TiO2 nanotube arrays as anode material for lithium ion batteries

In this work, we report the synthesis of TiO2 nanotube arrays with Au nanocrystals (Au@TiO2) via magnetron sputtering and thermal annealing at 450 °C. The prepared TiO2 nanotube arrays are characterized by field emission scanning electron microscopy, X-ray diffraction and transmission electron microscopy. The annealing leads to the formation of a layer of Au nanocrystals on the surface of TiO2 nanotubes and the dewetting of Au nanofilms on the top of TiO2 nanotube arrays. Using the Au@TiO2 nanotube arrays as anode material, we prepare lithium-ion half cells, and study the electrochemical performance of the lithium-ion half cells. The experimental results show that the lithium-ion half cells with the Au@TiO2 nanotube arrays prepared with the thickest Au film of 160 nm have the smallest charge-transfer resistance and the lithium-ion half cells with TiO2 nanotube arrays have the largest charge-transfer resistance. The specific capacity of the lithium-ion half cells with the Au@TiO2 nanotube arrays prepared with Au nanofilm of 120 nm is ~185 mAh·g−1, about twice of those with TiO2 nanotube arrays after 200 cycles. The Au nanocrystals in TiO2 nanotube arrays improve the cycle stability of the lithium-ion half cells with the Au@TiO2 nanotube arrays as anode material.

Electrochemical behavior and self-organization of porous Sn nanocrystals@acetylene black microspheres in lithium-ion half cells

We report a facile route to synthesize porous Sn nanocrystals@acetylene black microspheres (Sn@AB MSs) via a galvanic replacement reaction of Zn microspheres in a SnCl2 solution consisting of acetylene black (AB). The half cells of lithium-ion batteries with the Sn@AB MSs as the working electrode have a charge capacity of 480.8 mA h g−1 at 100 mA g−1 after 100 cycles, and the charge capacity of the half cells after the 100th cycle is slightly larger than that after the 80th cycle. The SEM images reveal that the electrode layer from the Sn@AB MSs experiences surface cracking during electrochemical cycling, while prolonged cycling leads to the closure of cracks. Electrochemical cycling induces self-organization of Sn and AB to form rose-like porous Sn@AB/Li2SnO3 microflowers from porous Sn@AB MSs. The closure of cracks and formation of porous Sn@AB/Li2SnO3 microflowers likely cause the increase of the charge capacity. The experimental results demonstrate that the porous Sn@AB MSs with acetylene black around Sn can alleviate the large volumetric strain due to lithiation/delithiation, reduce the migration distance of lithium to active sites, and promote exceptional Li storage, leading to better cycling stability.

New Electrolyte Composition for High-Voltage Lithium-Ion Cathodes – Enhancing the Cycling Stability in Half- and Full-Cells

The steadily rising utilization of lithium-ion batteries for large-scale applications, in particular, electric vehicles requires the development of cell chemistries that offer increased energy and power densities.1,2 Essentially, there are two options to enhance the energy density: Increasing the capacity of the employed active materials and/or elevating the full-cell voltage by switching to high-voltage cathode materials. The latter, however, face the great challenge to identify a suitable electrolyte composition, as commonly used organic carbonate-based electrolyte are not sufficiently stable towards oxidation. To avoid the resulting detrimental side reactions, the use of electrolyte additives is easily implementable into common cell manufacturing technologies and, thus, very cost-efficient.3,4 For such reason, a plethora of electrolyte additives has been reported in recent years, but frequently these additives have been proven only to enhance the performance for selected cathode materials, while particularly the evaluation with graphite-based anodes has been commonly overlooked. Herein, we report on a new electrolyte composition, incorporating functional electrolyte additives for high-voltage cathode materials like LiNi0.5Mn1.5O4 or 5V-olivines, which moreover reveal a beneficial impact also for graphite-based anodes and, consequently, also in lithium-ion full-cells. As a result, lithium-ion half- and full-cells with a cell voltage of >4.5 V show a greatly enhanced cycling stability, increased capacities, and improved efficiencies. References B. Scrosati, J. Hassoun, and Y.-K. Sun, Energy Environ. Sci., 4, 3287 (2011).D. Bresser et al., J. Power Sources, accepted manuscript (2018).S. S. Zhang, J. Power Sources, 162, 1379–1394 (2006).J. Kalhoff, G. G. Eshetu, D. Bresser, and S. Passerini, ChemSusChem, 8, 2154–2175 (2015).

Microwave-assisted hydrothermal synthesis of hollow flower-like Zn2V2O7 with enhanced cycling stability as electrode for lithium ion batteries

In this paper, hollow flower-like Zn2V2O7 have been prepared by a rapid microwave-assisted hydrothermal method. The diameter of microflower is about 3.0–4.0 μm and the thickness of subunit nanosheet is about 12.9–15.5 nm. As anode of lithium ion half cell, the as-synthesized powder delivers an initial discharge capacity of 1179 mAh g−1, which maintain of 882.5 mAh g−1 after 100 cycles at 50 mA g−1 in 0.01–3.00 V. The cyclability is significantly higher than that of the reported single nanoparticles, which can be attributed to the unique hollow nano/micro structure.

One-pot synthesis and characterization of MnCO3 hierarchical micro/nano twin-spheres with superior lithium storage performances

In this work, we reported a one-pot method to synthesize novel MnCO3 hierarchical micro/nano twin-spheres by a simple chemical precipitation method. The structure and morphology of the obtained powder are characterized by X-ray powder diffraction and field emission-scanning electron microscopy. As anode material of lithium-ion half cells, the as-prepared MnCO3 deliver a very high capacity, extra cycling stability and excellent rate capability. The discharge capacity of 890 mAh g−1 at 0.1 C is achieved after 100 cycles, showing a great application prospect in LIBs. The higher current charge–discharge and electrochemical impedance spectroscopy data indicate that material integrity is kept along the lithium ions insertion/extraction processes. The combination of nano-sizing, multiporous, and especially, the 3-dimensional hierarchical micro/nano structures are responsible for the superior lithium storage performances.

Layer structured graphene/porous ZnCo2O4 composite film for high performance flexible lithium-ion batteries

There is growing interest in flexible and reliable energy storage devices to meet the special needs for next-generation flexible electronics. In this work, graphene/porous ZnCo2O4 composite film with unique layered nanostructure is fabricated. The ZnCo2O4 nanocrystallites in the composite film randomly interconnected with each other in the 2D plane to form unique sheet-like morphology with a large number of nanopores, which are further sandwiched by graphene sheets. When it is evaluated as the anode material in lithium-ion half cells, this hybrid film electrode shows high electrochemical performance with a charge capacity of 874 mAh g−1 at 100 mA g−1, and demonstrates excellent cycling stability with only 2.7% capacity loss after 1000 cycles at 1 A g−1. Furthermore, a flexible full battery using the free-standing graphene/porous ZnCo2O4 film as the anode is fabricated in pouch form. The excellent electrical conductivity and porous nanostructure of the hybrid film electrode enable rapid electron and ion transport. Thus, the flexible full battery exhibits good flexibility and superior electrochemical performances simultaneously.

Hierarchical NiCo2O4 nanosheets grown on hollow carbon microspheres composites for advanced lithium-ion half and full batteries

Hierarchical ultrathin NiCo2O4 nanosheeets grown on uniform hollow carbon microspheres (HC@NiCo2O4) are designed and fabricated by a solvothermal reaction followed with an annealing process. When evaluated as an anode for lithium ion batteries, the as-prepared HC@NiCo2O4 microspheres exhibit excellent electrochemical performance (a high reversible capacity of 1015 mA h g−1 after 100 cycles at a current density of 0.1 A g−1 and a high capacity of 805 mA h g−1 even at a high current density of 0.5 A g−1). By pairing with the LiCoO2 cathode, the HC@NiCo2O4 anode also manifests excellent performance in full cells. The outstanding electrochemical performance in half and full cells can be attributed to its unique structure, which can not only promote the contact of electrode and electrolyte during the charge and discharge processes, but also shorten the transmission path of electrons and ions. More importantly, this study inspires a better design of various metal oxide/carbon electrode materials for high performance lithium ion batteries.