High-performance Lithium-ion Battery Anodes Research Articles

High performance columnar-like Fe2O3@carbon composite anode via yolk@shell structural design

Abstract Conversion-type reaction anode materials with high specific capacity are attractive candidates to improve lithium ion batteries (LIBs), yet the rapid capacity fading and poor rate capability caused by drastic volume change and low electronic conductivity greatly hinder their practical applications. To circumvent these issues, the successful design of yolk@shell Fe2O3@C hybrid composed of a columnar-like Fe2O3 core within a hollow cavity completely surrounded by a thin, self-supported carbon (C) shell is presented as an anode for high-performance LIBs. This yolk@shell structure allows each Fe2O3 core to swell upon lithiation without deforming the carbon shell. This preserves the structural and electrical integrity against pulverization, as revealed by in situ transmission electron microscopy (TEM) measurement. Benefiting from these structural advantages, the resulting electrode exhibits a high reversible capacity (1013 mAh g−1 after 80 cycles at 0.2 A g−1), outstanding rate capability (710 mAh g−1 at 8 A g−1) and superior cycling stability (800 mAh g−1 after 300 cycles at 4 A g−1). A Li-ion full cell using prelithiated yolk@shell Fe2O3@C hybrid as the anode and commercial LiCoO2 (LCO) as the cathode demonstrates impressive cycling stability with a capacity retention of 84.5% after 100 cycles at 1 C rate, holding great promise for future practical applications.

Na2SnO3 as a novel anode for high performance lithium storage and its electrochemical reaction mechanism

Herein, Na2SnO3 is employed as an anode for rechargeable lithium ion battery (LIB). We thoroughly investigated the electrochemical performance of Na2SnO3 in comparison with the most commonly used Sn based oxides, such as SnO2 and Li2SnO3. It is found that Na2SnO3 is greatly superior to SnO2 and Li2SnO3 in terms of capacity, cycling stability and rate capability. Impressively, Na2SnO3 presents favorable specific capacity of 480 mA h g−1 at current density of 200 mA g−1 after 100 cycles and still delivers a capacity of 439 mA h g−1 at extremely large current density of 1000 mA g−1, which are leading the performance in anodes for LIBs. Ex situ SEM analysis of anodes after different cycles revealed the surface microstructure of anodes plays a critical role in determining cycling stability. The SEM results show big cracks on the surface of electrode for SnO2 after less 15 cycles and for Li2SnO3 after more 100 cycles, resulting from their severe volume change during charging-discharging process. However, Na2SnO3 electrode exhibits uniform surface morphology after 100 cycles. It is concluded the “Na2O″ intrinsic matrix of Na2SnO3 combining with “Li2O″ formed from the conversion reaction can act as a mixture buffering matrix that contributes to keeping the electrochemically formed nanoscale Sn particles apart and preventing their agglomeration during Li−Sn alloy formation and decomposition, thus inhibiting the volume expansion and the capacity fading by maintaining the electrode integrity. In addition, the electrochemical reaction mechanism of Na2SnO3 with Li is investigated by ex situ XRD technique. The findings in this study provide a new valuable anode for high-performance LIBs and an insightful viewpoint of developing anode materials with high electrochemical performance by introducing the electrochemical inactive intrinsic matrix.

Nanocomposite of Mo2N Quantum Dots@MoO3@Nitrogen-Doped Carbon as a High-Performance Anode for Lithium-Ion Batteries

A superstructural nanocomposite of Mo2N quantum dots@MoO3@nitrogen-doped carbon is synthesized to overcome the disadvantages of poor cycling stability and low ionic/electronic conductivity of the M...

3D Graphene Nanostructure Composed of Porous Carbon Sheets and Interconnected Nanocages for High-Performance Lithium-Ion Battery Anodes and Lithium–Sulfur Batteries

Three-dimensional (3D) graphene materials are attractive in energy storage, but they mostly have disordered microstructures and suffer from weak strength. Here, inspired by a plant, philodendron he...

Iron-Doping-Induced Phase Transformation in Dual-Carbon-Confined Cobalt Diselenide Enabling Superior Lithium Storage.

Transition metal chalcogenides (TMCs) have been investigated as promising anodes for high-performance lithium-ion batteries, but they usually suffer from poor conductivity and large volume variation, thus leading to unsatisfactory performance. Although nanostructure engineering and hybridization with conductive materials have been proposed to address this concern, a better performance toward practical device applications is still highly desired. Herein, we report an iron-doping-induced structural phase transition from pyrite-type (cubic) to marcasite-type (orthorhombic) phases in porous carbon/rGO-coupled CoSe2. The dual-carbon-confined orthorhombic CoSe2 ( o-Fe xCo1- xSe2@NC@rGO) composites exhibit dramatically enhanced lithium storage performance (920 mAh g-1 after 1000 cycles at 1.0 A g-1) over cubic CoSe2-based composites ( c-CoSe2@NC@rGO). The combined experimental studies and density functional theory calculations reveal that this doping-induced structural phase transformation strategy could create a favorable electronic structure and ensure a rapid charge transfer. These results demonstrate that the phase-transformation engineering may provide another opportunity in the design of high-performance TMC-based electrodes.

Nitrogen-doped carbon coated SnO2 nanoparticles embedded in a hierarchical porous carbon framework for high-performance lithium-ion battery anodes

SnO2 is one of the promising anode materials for the next-generation lithium-ion batteries due to its high theoretical capacity. The main challenges of SnO2 include large volume change during cycling, partially reversibility between SnO2 and Sn, and unstable solid-electrolyte interphase. Herein, we demonstrate a novel structure design of SnO2-based anode, in which SnO2 nanoparticles are embedded in a hierarchical porous carbon framework and further coated by the uniform Nitrogen-doped carbon layer. The hierarchical porous carbon framework can provide void space for the SnO2 expansion, while the Nitrogen-doped carbon coating can act as a buffer layer to reduce the amount of irreversible solid-electrolyte interphase. This peculiar structure can also build highly conductive network, and promote the reversible conversion from Sn to SnO2 by preventing the agglomeration of the intermediate Sn product. Therefore, the obtained SnO2@HPC@NC composite exhibits remarkable electrochemical performance with a high specific capacity of 1100 mAh g−1 after 100 cycles at 0.1 A g−1 and superior long-term stability over 500 cycles at 1 A g−1.

Low-cost heterogeneous dual-carbon shells coated silicon monoxide porous composites as anodes for high-performance lithium-ion batteries

To develop low-cost, high-capacity and long-life anode materials for lithium-ion batteries, glucose-C and F-doped C coated SiO composites with adjustable pore structure (p-SiO@gl-C@F-doped C) are synthesized by facile and scalable methods. The combination of the heterogeneous dual-carbon shells and porous structure significantly promotes the reaction kinetics of the electrode, effectively suppresses and buffers the volume expansion of SiO, and largely enhances the stability of solid electrolyte interface of the electrode. In a half cell, the optimized p-SiO@gl-C@F-doped C (7:3) composite shows a stable discharge capacity of 785 mAh g−1 at a current density of 200 mA g−1. The discharge capacity is maintained at 772 mAh g−1 after 200 cycles. At a current density of 400 mA g−1, the electrode shows a discharge capacity of 633 mAh g−1 after 500 cycles, with a capacity degradation of ∼0.0096% per cycle from the 2nd cycle to the 500th cycle. The full cell which is composed of the commercial LiFePO4 as a cathode and the optimized composite as an anode, exhibits high capacity and good cycling stability.

Li-Ions Transport Promoting and Highly Stable Solid-Electrolyte Interface on Si in Multilayer Si/C through Thickness Control.

Lithium-ion batteries (LIBs) have been considered as promising electrochemical energy storage devices due to the high volumetric, gravimetric capacity and high power density. The charge/discharge rate and power output of LIBs largely depend on the transport property of lithium-ions (Li-ions). The Li-ions diffusion coefficient and diffusion length are the critical factors influencing the charge/discharge rate of LIBs. In this work, we present that silicon-carbon (Si-C) interfaces in an amorphous Si/C multilayer electrode promote the transport of Li-ions along the direction not only perpendicular to but also parallel to the Si-C interfaces after electrode cracking. The electrode, stacked with 5 nm amorphous carbon and 10 nm amorphous Si, has the most stable solid-electrolyte interface (SEI) formed at the cracks, even when the Si is in direct contact with the electrolyte. It exhibits highly stable cycle performance and a high retained specific capacity. Electron microscopy characterization shows that the structure contains uniform Si/C multilayer blocks of about 1 μm. A micro-size hierarchical multilayer-block design strategy with proper stacking thickness of amorphous Si and carbon is thus proposed for high-performance film LIB anodes. Furthermore, the results may be used as a reference for the design of high-performance core-shell LIB anodes.

Dual Carbonaceous Materials Synergetic Protection Silicon as a High-Performance Free-Standing Anode for Lithium-Ion Battery.

Silicon is the one of the most promising anode material alternatives for next-generation lithium-ion batteries. However, the low electronic conductivity, unstable formation of solid electrolyte interphase, and the extremely high volume expansion (up to 300%) which results in pulverization of Si and rapid fading of its capacity have been identified as primary reasons for hindering its application. In this work, we put forward to introduce dual carbonaceous materials synergetic protection to overcome the drawbacks of the silicon anode. The silicon nanoparticle was coated by pyrolysed carbon, and meanwhile anchored on the surface of reduced graphene oxide, to form a self-standing film composite (C@Si/rGO). The C@Si/rGO film electrode displays high flexibility and an ordered porous structure, which could not only buffer the Si nanoparticle expansion during lithiation/delithiation processes, but also provides the channels for fast electron transfer and lithium ion transport. Therefore, the self-standing C@Si/rGO film electrode shows a high reversible capacity of 1002 mAh g−1 over 100 cycles and exhibits much better rate capability, validating it as a promising anode for constructing high performance lithium-ion batteries.

Rational Design of the Robust Janus Shell on Silicon Anodes for High-Performance Lithium-Ion Batteries.

The high-capacity silicon anode is regarded as a promising electrode material for next-generation lithium-ion batteries. Unfortunately, its practical application is still severely hindered by electrode fracture and unstable solid electrolyte interphase during cycling. Herein, we design a structure of encapsulating silicon in a robust "janus shell", in which an internal graphene shell with sufficient void space is used to absorb the mechanical stress induced by volume expansion, and the conformal carbon outer shell is introduced to strongly bond the loosely stacked graphene shell and simultaneously seal the nanopores on the surface. With the ultrastable janus carbon shell, the excellent structural integrity of the electrode and stable solid electrolyte interphase layer could be effectively preserved, resulting in an impressive cycling behavior. Indeed, the as-synthesized anodes demonstrate superior cycle stability and excellent rate performance, delivering a high reversible capacity of 1416 mA h g-1 at a current density of 0.2 A g-1 and 852 mA h g-1 at a high current density of 5 A g-1. Remarkably, the superior capacity retention of 88.5% could be achieved even after 400 cycles at a high current density of 2 A g-1. More importantly, this work opens up a novel avenue to address high-capacity anodes with a large volume change.

Facile synthesis of Y2(MoO4)3 nanowires as anode materials towards enhanced lithium storage performance

Owing to the high theoretical capacity, molybdenum (Mo)-based materials are promising as high-performance anode for lithium-ion batteries (LIBs). Therefore, Y2(MoO4)3 is investigated as anode candidate for the first time in this work. Moreover, in an attempt to improve ionic diffusivity and capacity retention of Y2(MoO4)3, molybdenum-based Y2(MoO4)3 nanowires are successfully formed by a feasible electrospinning method. And the morphologies of as-prepared sample are observed by scanning electron microscope (SEM), transmission electron microscope (TEM) and high-resolution transmission electron microscope (HRTEM). Herein, the Y2(MoO4)3 nanowires show a remarkable charge specific capacity of 480.1mAhg−1 with 67.1% capacity retention at 100mAg−1 after 100cycles. While the capacity retention of Y2(MoO4)3 micro-particles is only 24.4% under the same conditions. Besides, ex-situ X-ray diffraction (XRD), ex-situ TEM and ex-situ X-ray photoelectron spectrometer (XPS) tests are carried to study lithium storage reaction of Y2(MoO4)3 upon the charge/discharge reactions. The results confirm that the Y2(MoO4)3 undergoes a typical conversion reaction, accompanied by the irreversible particle pulverization of structure.

Solvothermal alcoholysis synthesis of hierarchically porous TiO2-carbon tubular composites as high-performance anodes for lithium-ion batteries

Hierarchically porous one-dimensional (1D) TiO2-carbon tubular composites (TiO2C-Ts) with interconnected nanoflakes on the porous tube walls, have been successfully created using a simple solvothermal alcoholysis followed by a subsequent calcination process. The as-prepared TiO2C-Ts demonstrate high electrical conductivity due to the 1D tubular frameworks and the interconnected porous tube walls, offering fast ion/electron transport paths and large space for storing the electrolyte, while buffering the volume change during the Li+ insertion/extraction process. When evaluated as an anode in a lithium-ion battery, the optimized TiO2C-Ts600 electrode displays a remarkable reversible capacity of 534 mA h g−1 after 100 cycles at 180 mA g−1 and an impressive capacity of 284.9 mA h g−1 (∼80% capacity retention) after 3000 cycles at 3.5 A g−1. Further, the performance of the TiO2C-Ts600 electrode is also investigated in a full cell using LiFePO4 as the cathode, demonstrating highly reversible discharge capacity (353.8 mA h g−1 after 100 cycles at 100 mA g−1, corresponding to capacity retention of ∼73%) and superior rate capability (254.4 mA h g−1 at 1.0 A g−1), suggesting its great potential application in high-performance energy storage devices.

Graphene-supported cubic hollow carbon shell-coated germanium particles as high-performance anode for lithium-ion batteries

Germanium-based materials are considered to be an alternative material for high energy density lithium-ion battery anodes due to their superior theoretical capacity. However, the severe volume expansion during the lithium insertion and the easily agglomerated tendency of Ge nanoparticles become the key obstacles to the stable cycle and capacity retention of Ge anodes. Herein, we designed a double-layered protective structure in which the cubic hollow [email protected] hybrids are uniformly dispersed on reduced graphene oxide sheets ([email protected]) through conventional dopamine-coated precursor and subsequent carbothermal reduction processes. In the synthesized [email protected] hybrids, the large-area rGO sheets cooperate with the amorphous carbon layer to accommodate and buffer the volume expansion of Ge particles, and to ensure that the Ge nanoparticles are in a separated state to the utmost extent. The [email protected] electrode which is employed in lithium-ion battery owns the reversible capacities of 1183 mAh·g−1 at the specific current of 100 mA g−1 and 710 mAh·g−1 at 1 A g−1 for 200 cycles. In addition, it exhibited good cycle stability, rate reversibility and electronic conductivity, and is a potential anode material with high performance and long-cycle capability.

Carbon cloth–supported Fe2O3 derived from Prussian blue as self-standing anodes for high-performance lithium-ion batteries

The carbon cloth (CC)–supported Prussian blue (PB) composite was firstly prepared by using CC as the substrate and PB as active material through a solution impregnation method. Then, the Fe2O3/CC material was obtained by the subsequent high-temperature calcination of PB/CC. This is the first example of composites based on CC and PB (or PB analogues)-derived metal oxides. The resulting Fe2O3/CC composite can be employed directly as binder-free anodes for lithium-ion batteries (LIBs), exhibiting superior electrochemical performances to pure CC and Fe2O3. The mass specific capacity of Fe2O3/CC was about 395 mA h g−1 (an areal capacity of 5.1 mA h cm−2) at 100 mA g−1 with almost no decay after 135 discharge/charge cycles. The outstanding lithium storage properties of Fe2O3/CC benefit from the synergistic interaction between CC and Fe2O3.

Porous hierarchical spinel Mn-doped NiCo2O4 nanosheet architectures as high-performance anodes for lithium-ion batteries and electrochemical reaction mechanism

We report an efficient co-precitation and subsequent annealing chemical route to synthesize porous hierarchical Mn-doped NiCo2O4 nanosheet architectures. The as-synthesized products exhibit unique porous hierarchical structures. When tested as anode materials for lithium-ion batteries, the Mn-doped NiCo2O4 architectures show excellent performances of Li+ storage. Under a current density of 0.5 A g−1, 5% Mn–NiCo2O4 electrode is capable of retaining a specific capacity of 1428 mA h g−1 over 80 cycles. Even at 2 and 5 A g−1, comparable capacities of 1220 and 987 mA h g−1 could still be achieved, indicating a superior rate capability. Ex-situ XRD, HRTEM measurements reveal the electrochemical mechanism of NiCo2O4 architecture anode. On basis of above analyses, the excellent electrochemical performances of porous hierarchical Mn-doped NiCo2O4 nanosheet architectures should be ascribed to the following aspects. (1) The self-adsorbed 2D nanosheet hierarchical multilayer architectures are favorable to the infiltration of electrolyte and beneficial to the available space for lithium ion diffusion. (2) Mn doping and multiple nanosheets may synergistically enhance the electrical/ionic conductivity, reversible capacity, and mechanical stability of electrodes. (3) Porous continuous network structure can enlarge the contact area of Li2O and Ni, Co, CoO nanoparticles, thus improves the Li+ storage and rate performance of NiCo2O4 -based electrode.

Scalable synthesis of ant-nest-like bulk porous silicon for high-performance lithium-ion battery anodes

Although silicon is a promising anode material for lithium-ion batteries, scalable synthesis of silicon anodes with good cyclability and low electrode swelling remains a significant challenge. Herein, we report a scalable top-down technique to produce ant-nest-like porous silicon from magnesium-silicon alloy. The ant-nest-like porous silicon comprising three-dimensional interconnected silicon nanoligaments and bicontinuous nanopores can prevent pulverization and accommodate volume expansion during cycling resulting in negligible particle-level outward expansion. The carbon-coated porous silicon anode delivers a high capacity of 1,271 mAh g−1 at 2,100 mA g−1 with 90% capacity retention after 1,000 cycles and has a low electrode swelling of 17.8% at a high areal capacity of 5.1 mAh cm−2. The full cell with the prelithiated silicon anode and Li(Ni1/3Co1/3Mn1/3)O2 cathode boasts a high energy density of 502 Wh Kg−1 and 84% capacity retention after 400 cycles. This work provides insights into the rational design of alloy anodes for high-energy batteries.

A new design for Si wears double jackets used as a high-performance lithium-ion battery anode

Since most active nanoparticles (Si, Sn, TiO2, SnO2, etc.) are simply decorated on the graphene surface instead of being contained between the graphene nanoarray, they are easily peeled off during the long-term cycling. A new Si-based double jackets nanostructure synthesized by synergistic coupling of TiO2@RGO coating layer, supporting large current density for charge/discharge, is reported as an anode material for lithium-ion batteries. The new heterostructure modifies the surface of Si and TiO2 to ensure a firm bond between the interfaces, layer by layer self-assembly dispersed in the reduced graphene oxide (Si@TiO2@RGO). Compared with the regular Si@G composites, Si@TiO2@RGO exhibits excellent electrochemical performance, mainly due to the strong interfacial binding force among the three, thus the integrity of the electrode structure is ensured in the lithiation/delithiation process. As a consequence, the Si@TiO2@RGO electrode exhibits a stable reversible specific capacity of 1679.1 mAh g−1 at a large current density of 1.4 A g−1 after 900 cycles.

Uniform Distribution of Alloying/Dealloying Stress for High Structural Stability of an Al Anode in High-Areal-Density Lithium-Ion Batteries.

Aluminum (Al) is one of the most attractive anode materials for lithium-ion batteries (LIBs) due to its high theoretical specific capacity, excellent conductivity, abundance, and especially low cost. However, the large volume expansion, originating from the uneven alloying/dealloying reactions in the charge/discharge process, causes structural stress and electrode pulverization, which has long hindered its practical application, especially when assembled with a high-areal-density cathode. Here, an inactive (Cu) and active (Al) co-deposition strategy is reported to homogeneously distribute the alloying sites and disperse the stress of volume expansion, which is beneficial to obtain the structural stability of the Al anode. Owing to the homogeneous reaction and uniform distribution of stress during the charge/discharge process, the assembled full battery (LiFePO4 cathode with a high areal density of ≈7.4 mg cm-2 ) with the Cu-Al@Al anode, achieves a high capacity retention of ≈88% over 200 cycles, suggesting the feasibility of the interfacial design to optimize the structural stability of alloying metal anodes for high-performance LIBs.

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.

Submicron-sized α-Fe2O3 single crystals as anodes for high-performance lithium-ion batteries

Abstract Although Fe2O3 has been widely used as an anode material in lithium-ion batteries, its synthesis is complicated when a porous structure/nanoscale is needed to accommodate large volume variations and low electron conductivity. In this study, a submicron-sized α-Fe2O3 single-crystal (α-Fe2O3(SMSC)) is synthesized by directly annealing Fe(NO3)3⸳9H2O in an argon for the production of anodes for lithium-ion batteries. Unlike previously reported pure Fe2O3 which has poor electrochemical performance, α-Fe2O3(SMSC) exhibits excellent lithium storage properties. At a current density of 400 mA g−1, the discharge capacity is maintained at 970 mAh g−1 after 300 cycles. At a current density of 3200 mA g−1, the prepared anode shows a stable discharge capacity of ∼680 mAh g−1. During delithiation, the Li+ diffusion coefficient in the α-Fe2O3(SMSC) electrode is closely associated with the potential, which varies from 10−8 to 10−11 cm2 s−1. After the electrode was charged to 3.0 V, the products are shown to contain crystalline Li2Fe3O4, Fe3O4, and Li2O, but surprisingly, crystalline FeO is not detected. After combination with 30 wt% graphite, α-Fe2O3(SMSC) shows improved electrochemical properties, confirming that this crystal can be used as the main active component in high-performance anode composites.