Advanced Lithium-ion Battery Anode Research Articles

The sandwiched buffer zone enables porous SnO2@C micro-/nanospheres to toward high-performance lithium-ion battery anodes

With high theoretical specific capacity and relatively safe working potential, SnO2 has drawn widespread attention as a promising candidate of advanced anode for next generation lithium-ion batteries. However, the practical application of SnO2 anode in lithium-ion batteries is severely blocked by some shortcomings such as the inferior rate capability, fast capacity decay and low initial coulombic efficiency during charge/discharge process. Gratifyingly, there are many works which have demonstrated that the SnO2 anode achieves extra improvement in lithium storage performance after being reduced to nanoscale and embedded into porous carbon matrixes. Herein, porous SnO2@C micro-/nanospheres with a sandwiched buffer zone resulted from unevenly radial distribution of pores in carbon micro-/nanospheres are prepared for the first time. These SnO2@C micro-/nanospheres consist of small SnO2 nanoparticles embedded within porous carbon micro-/nanospheres with a sandwiched buffer zone. The results of this study indicate that the sandwiched buffer zone of carbon micro-/nanospheres and the confinement effect of nanopores on small SnO2 nanoparticles synergistically contribute to outstanding structural stability and excellent electrochemical performance of thus porous SnO2@C micro-/nanospheres. Besides, it is found that the lithium storage performance of the SnO2@C micro-/nanospheres can be tuned by adjusting the SnO2 contents. As a result, the as-prepared SnO2@C micro-/nanospheres with an optimalizing SnO2 content exhibit the best performance, delivering a high capacity of 955 mAh g−1 at 200 mA g−1 after 250 cycles as well as a high capacity of 836 mAh g−1 at even 1000 mA g−1 after 350 cycles.

A Low-Cost and High-Capacity SiO x /C@graphite Hybrid as an Advanced Anode for High-Power Lithium-Ion Batteries.

Silicon suboxide (SiOx) is one of the most promising anodes for the next-generation high-power lithium-ion batteries because of its higher lithium storage capacity than current commercial graphite, relatively smaller volume variations than pure silicon, and appropriate working potential. However, the high cost, poor cycling stability, and rate capability hampered its industrial applications due to its complex production process, volume changes during Li+ insertion/extraction, and low conductivity. Herein, a low-cost and high-capacity SiOx/C@graphite (SCG) hybrid was designed and synthesized by a facile one-pot carbonization/hydrogen reduction process of the rice husk and graphite. As an advanced anode for lithium-ion batteries, the SiOx/C@graphite hybrid delivers a high reversible capacity with significantly enhanced cycling stability (842 mAh g–1 after 300 cycles at 0.5 A g–1) and rate capability (562 mAh g–1 after 300 cycles at 1 A g–1). The great improvement in performances could be attributed to the positive synergistic effect of SiOx nanoparticles as lithium storage active materials, the in situ-formed carbon matrix network derived from biomass functioning as an efficient three-dimensional conductive network and spacer to improve the rate capability and buffer the volume changes, and graphite as a conductor to further improve the rate capabilities and cycling stability by increasing the conductivity. The low-cost and high-capacity SCG derived from rice husk synthesized by a facile, scalable synthetic method turns out to be a promising anode for the next-generation high-power lithium-ion batteries.

Graphite/Graphene Composites from the Recovered Spent Zn/Carbon Primary Cell for the High-Performance Anode of Lithium-Ion Batteries.

Exploring electrochemically chapped graphite/graphene composites derived from the bulk carbon rod of the spent Zn/carbon primary cell is for the advanced high-capacity lithium-ion battery anode. It is found that the synthesized graphitic carbon has grain boundary defects with multilayered exfoliation. Such material exhibits an average specific capacity of 458 mA h g–1 at 0.2 C, which is higher than the theoretical specific capacity (372 mA h g–1) of graphite. The differential specific capacity calculations also show no significant difference in lithiation and delithiation potentials for the exfoliated sample at the low voltage. However, two additional plateaus have also been observed at ∼1.2 and 2.5 V, which confirms the formation of the LiC3 phase similar to lithiation of graphene. Hence, the superior lithiation ability and thecycling stability of defected graphite/graphene flakes may be useful for the sustainable development of next-generation high energy lithium-ion batteries. Also, waste recovery tends to reduce the risk of environmental pollution and the cost of raw materials.

Cost-effective production of SiO2/C and Si/C composites derived from rice husk for advanced lithium-ion battery anodes

Rice husk, an agricultural waste, was chosen as the low-cost source to synthesize silica/carbon (SiO2/C) and silicon/carbon (Si/C) composite materials through a simple calcination and magnesiothermic reduction reaction, respectively. After rice husk was calcined, SiO2 and C coexisted in the sample in which the nanosized SiO2 particles were distributed on C plate. When Si/C composite was fabricated by magnesiothermic reduction reaction, Si and C were obtained together with small amount of SiC phase. The rice husk-derived SiO2/C and Si/C composites provided different specific characteristics in which good cycling stability was found in SiO2/C composite while Si/C gave high specific capacity. This work suggested that the facile preparation strategy with environmental friendliness and low-cost effective can be used to produce SiO2/C and Si/C composites with good electrochemical characteristics. The preparation technique used in this work may be available for other biomass anode materials.

Surface modification of coordination polymers to enable the construction of CoP/N,P-codoped carbon nanowires towards high-performance lithium storage

A one-dimensional hybrid with N,P co-doped carbon nanowires threaded CoP nanoparticles is rationally fabricated by employing surface modified coordination polymers as a precursor. Ultrasmall CoP nanoparticlesare well encapsulated in N,P co-doped carbon nanowires, which can effectively buffer the volume expansion of active CoP and facilitate fast lithium-ion/electron transfer during charge/discharge processes. Moreover, N,P co-doped carbon with high defect density and graphitic-N content are obtained, which facilitates high lithium storage capacity and fast electron transfer. As a result, attractive lithium storage properties are gained by employing this unique architecture as an anode material for lithium-ion batteries, including high reversible charge/discharge capacities, good rate capability, and excellent long-term cycling stability. Kinetic investigation shows that the fast lithium ion uptake/release is related to the remarkable capacitive contribution. This work may offer an effective way for design well-defined transition metal phosphide-based anodes for advanced lithium-ion batteries.

Bimetallic organic framework derivation of three-dimensional and heterogeneous metal selenides/carbon composites as advanced anodes for lithium-ion batteries.

Heterogeneous structures have been attracting increasing attention in energy storage and conversion applications due to the phase interface and synergistic effect of multiple components. Herein, bimetal organic framework analogues were introduced to construct a Zn/Co bimetallic selenide heterostructure within a 3D-porous N-doped carbon matrix by a NaCl template-assisted lyophilization and annealing process. The cross-linked 3D network can enhance the transport kinetics for both lithium ions and electrons. The stress resulting from the cycling process can be released by interconnected channels in the composite. ZnSe and CoSe2 experience electrochemical reactions at different potentials, which can buffer volume changes mutually to effectively increase structural stability. Meanwhile, abundant active sites due to the heterostructure enhance pseudocapacitive performance and reaction kinetics, resulting in high specific capacity and good rate performance. As anode materials for lithium-ion batteries, the three-dimensional ZnSe/CoSe2-C composite exhibits a high reversible capacity of 700 mA h g-1 after 500 cycles at 1 A g-1.

NiS2 nanoparticles anchored on open carbon nanohelmets as an advanced anode for lithium-ion batteries.

Low intrinsic conductivity and large volume expansion seriously restrict the efficient lithium storage performance of metal sulfides. Here, we fabricate a hybrid material of NiS2 nanoparticles/carbon nanohelmets (NiS2/CNHs) to address the above issues. As an anode material in lithium-ion batteries, NiS2/CNHs exhibit excellent cycling stability (490 mA h g−1 after 3000 cycles at 5 A g−1) and rate properties (412 mA h g−1 at 10 A g−1), outperforming other NiSx-based anode materials. These remarkable performances originate from the three-dimensional helmet-like integrated architecture of NiS2/CNHs, which reduces the electrode resistance due to the tight combination between NiS2 and CNHs, provides efficient diffusion paths for the electrolyte and Li+ owing to the amorphous nanoporous carbon structure, and significantly mitigates the aggregation and buffers the large volumetric expansion of NiS2 nanoparticles upon long-term cycling thanks to the open three-dimensional architecture and well-dispersed NiS2 nanoparticles on it.

Silicon-nanoparticle-based composites for advanced lithium-ion battery anodes.

Lithium-ion batteries (LIBs) play an important role in modern society. The low capacity of graphite cannot meet the demands of LIBs calling for high power and energy densities. Silicon (Si) is one of the most promising materials instead of graphite, because of its high theoretical capacity, low discharge voltage, low cost, etc. However, Si shows low conductivity of both ions and electrons and exhibits a severe volume change during cycles. Fabricating nano-sized Si and Si-based composites is an effective method to enhance the electrochemical performance of LIB anodes. Using a small size of Si nanoparticles (SiNPs) is likely to avoid the cracking of this material. One critical issue is to disclose different types and electrochemical effects of various coupled materials in the Si-based composites for anode fabrication and optimization. Hence, this paper reviews diverse SiNP-based composites for advanced LIBs from the perspective of composition and electrochemical effects. Almost all kinds of materials that have been coupled with SiNPs for LIB applications are summarized, along with their electrochemical influences on the composites. The integrated materials, including carbon materials, metals, metal oxides, polymers, Si-based materials, transition metal nitrides, carbides, dichalcogenides, alloys, and metal-organic frameworks (MOFs), are comprehensively presented.

Mn2Sb2O7/Reduced Graphene Oxide Composites with High Capacity and Excellent Cyclic Stability as Anode Materials for Lithium‐Ion Batteries

AbstractFor the advancement of lithium‐ion batteries (LIBs), metal oxides with high theoretical specific capacities have been explored as anodes. Herein, we report a new metal oxide, Mn2Sb2O7‐anchored reduced graphene oxide (Mn2Sb2O7/RGO), as an advanced anode for LIBs. The Mn2Sb2O7/RGO anode exhibits a higher capacity and better capacity retention compared to Mn2Sb2O7, because the close contact between Mn2Sb2O7 and RGO facilitates charge transfer during cycling. The discharge capacity of Mn2Sb2O7/RGO reaches 706.72 mAh g−1 at 200 mA g−1 after 200 cycles. Even at 1000 mA g−1, the capacity loss per cycle of Mn2Sb2O7/RGO is only 0.0344 % for 600 cycles, indicating an excellent high‐rate cyclic stability compared to other Sb‐based oxides. These results forecast that Mn2Sb2O7/RGO is a potential anode for LIBs, providing a new insight into the selection of high‐performance anodes.

Bilayer-graphene-coated Si nanoparticles as advanced anodes for high-rate lithium-ion batteries

Silicon is a promising anode material for the next-generation of high-specific-energy lithium-ion batteries (LIBs), but commercial silicon still has difficulty in gaining both high rate capability and long cycle life for practical application due to poor electrical conductivity and an unstable solid electrolyte interface. Here, a simple electrode with bilayer-graphene-coated Si nanoparticles embedded in a porous current collector is adopted and exceptional electrochemical performance is obtained in lithium-ions batteries. A possible mechanism is analyzed from the insight provided from the conductivity balance between electrons and ions. Used as binder-free and additive-free anodes, the Si composite displays good rate capacity (up to 50 A g−1) and cycling stability (3000 cycles with ∼89% capacity retention). Coupled with a possible physical insight, economical and feasible fabrication process, the electrode designs developed are likely to stimulate more opportunities for the next-generation high-specific-energy LIBs with enhanced power. It is further demonstrated that even in a full-cell electrochemical test, it is stable for 260 cycles and 87% capacity retention is achieved.

Ultrafine MoO3 anchored in coal-based carbon nanofibers as anode for advanced lithium-ion batteries

Molybdenum trioxide (MoO3), which possesses unique layered nanostructure and high theoretical capacity, is currently under comprehensive research as one of the most promising lithium-ion anode materials. However, MoO3 suffers from sluggish electrode reaction kinetics and huge volume expansion, causing severe capacity fading during cycling processes. Herein, ultrafine MoO3 anchored in coal-based carbon fiber to form nanocomposites (MoO3/CCNFs) was prepared by electrospinning. The unique structure of the ultrafine MoO3 nanoparticles (1–3 nm) homogeneously embedded in coal-based carbon nanofibers showed advantages of short Li+ diffusion distance, fast reaction kinetics and reduced volume expansion. The specific surface area and pore volume of MoO3/CCNFs were increased induced by small molecular gas released during carbonization of the coal, which can supply more beneficial transport routes for electrolyte ions and relieve volume stress caused by Li+ insertion. Among all samples, 0.5-MoO3/CCNFs (the addition of coal was 0.5 g) exhibited excellent conductivity. As an anode for lithium storage, the 0.5-MoO3/CCNFs showed remarkable electrochemical properties with a high specific capacity of 801.1 mA h g−1 at 0.5 A g−1 after 200 cycles, as well as excellent rate capability. This work indicates that coal-based carbon nanofibers will allow further development in high performance MoO3 electrodes.

High-Throughput Production of Zr-Doped Li4 Ti5 O12 Modified by Mesoporous Libaf3 Nanoparticles for Superior Lithium and Potassium Storage.

Li4 Ti5 O12 is a promising anode for lithium-ion batteries due to its zero-strain properties. However, its low conductivity has greatly affected its rate performance. At the same time, the electrolyte decomposition during cycling also needs to be solved, especially at low cut-off voltage. Herein, using a high-throughput two-step method, we synthesized Zr-doped LTO modified by mesoporous LiBaF3 nanoparticles for alkali-ion storage. The doping of Zr can enhance the electronic conductivity and facilitate the rate performance. Meanwhile, the coating of mesoporous LiBaF3 nanoparticles can form a mesoporous surface with large pore size (ca. 3-10 nm), which can benefit the alkali ion diffusion and simultaneously restrain the formation of an excess solid electrolyte interface to a reasonable range. The optimized material is used as an advanced anode for both lithium-ion and potassium-ion batteries, and good battery behavior including high-rate performance and high stability is achieved.

Flexible Three-Dimensional Titanium-Dioxide-Based Hollow Nanoflower Arrays for Advanced Lithium-Ion Battery Anodes

The flexible three-dimensional hierarchical carbon cloth (CC)/TiO2@ZnO hollow nanoflower arrays are synthesized in a facile two-process, seed-free solvothermal method. This composite nanostructure ...

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

The poor cyclability of pure 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 LeafPowder®, 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) [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. Though good cycleability is obtained, the observed electrode swelling during cycling (Fig. 3) is not affordable for practical use. In this talk, we present some mitigation methods developed for suppression of electrode swelling of Si-LP anode and Si thin film anode, including the effects of additives (VC, FEC in Fig.4) [2], the effects of particle size, the effects of oxide content [3], the effects of pre-film formation [4], the effects of artificial SEI film [5], etc. 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.

Porous ZnO/Co3O4/N-doped carbon nanocages synthesized via pyrolysis of complex metal-organic framework (MOF) hybrids as an advanced lithium-ion battery anode.

Metal oxides have a large storage capacity when employed as anode materials for lithium-ion batteries (LIBs). However, they often suffer from poor capacity retention due to their low electrical conductivity and huge volume variation during the charge-discharge process. To overcome these limitations, fabrication of metal oxides/carbon hybrids with hollow structures can be expected to further improve their electrochemical properties. Herein, ZnO-Co3O4 nanocomposites embedded in N-doped carbon (ZnO-Co3O4@N-C) nanocages with hollow dodecahedral shapes have been prepared successfully by the simple carbonizing and oxidizing of metal-organic frameworks (MOFs). Benefiting from the advantages of the structural features, i.e. the conductive N-doped carbon coating, the porous structure of the nanocages and the synergistic effects of different components, the as-prepared ZnO-Co3O4@N-C not only avoids particle aggregation and nanostructure cracking but also facilitates the transport of ions and electrons. As a result, the resultant ZnO-Co3O4@N-C shows a discharge capacity of 2373 mAh g-1 at the first cycle and exhibits a retention capacity of 1305 mAh g-1 even after 300 cycles at 0.1 A g-1. In addition, a reversible capacity of 948 mAh g-1 is obtained at a current density of 2 A g-1, which delivers an excellent high-rate cycle ability.

Ordered mesoporous Si microspheres with nitrogen-doped carbon coating for advanced lithium-ion battery anodes

Silicon is considered as a promising anode candidate for the new generation of lithium-ion batteries by virtue of its extensive sources and ultrahigh theoretical specific capacity (4200 mA h g−1). The inevitable volume change during the lithiation process will lead to a series of troubles, which has become a major obstacle to the large-scale application of silicon-based electrodes. Herein, silicon microspheres with the ordered mesoporous structure are synthesized through magnesiothermic reduction, which allows void for volume expansion to prevent electrode material from pulverizing. Subsequently, the silicon microspheres are packaged with a polydopamine driven nitrogen-doped carbon layer, which is helpful to maintain the structural stability of electrode materials and enhance the electronic conductivity. The resulting OM-Si@C composite material exhibits remarkable lithium storage properties, which behaves a superior reversible specific capacity of 1751.7 mA h g−1 at 0.1 A g−1 after 100 cycles. Furthermore, it also shows excellent rate performance (1183.9 mA h g−1 at 2 A g−1) and long cycle stability.

In-situ Grown SnO2 Nanospheres on Reduced GO Nanosheets as Advanced Anodes for Lithium-ion Batteries.

Nanostructured tin dioxide (SnO2) has emerged as a promising anode material for lithium‐ion batteries (LIBs) due to its high theoretical capacity (1494 mA h g−1) and excellent stability. Unfortunately, the rapid capacity fading and poor electrical conductivity of bulk SnO2 material restrict its practical application. Here, SnO2 nanospheres/reduced graphene oxide nanosheets (SRG) are fabricated through in‐situ growth of carbon‐coated SnO2 using template‐based approach. The nanosheet structure with the external layer of about several nanometers thickness can not only accommodate the volume change of Sn lattice during cycling but also enhance the electrical conductivity effectively. Benefited from such design, the SRG composites could deliver an initial discharge capacity of 1212.3 mA h g−1 at 0.1 A g−1, outstanding cycling performance of 1335.6 mA h g−1 after 500 cycles at 1 A g−1, and superior rate capability of 502.1 mA h g−1 at 5 A g−1 after 10 cycles. Finally, it is believed that this method could provide a versatile and effective process to prepare other metal‐oxide/reduced graphene oxide (rGO) 2D nanocomposites.

Electrospun Co/Co3SnC0.7@N-CNFs as free-standing anode for advanced lithium-ion batteries

Sn is considered as a promising anode for lithium-ion batteries due to its low cost and high theoretical capacity (992 mA h g −1 with Li4.4Sn). However, the volume expansion (∼300%) during lithiation/delithiation process can result in the continuous pulverization of active materials and exfoliation from current collector, deteriorating the capacity and cycling performance. Here Co/Co3SnC0.7 N-doped carbon nanofibers are successfully synthesized by a feasible electrospinning method. And the materials as the self-standing anode for lithium-ion batteries reveal a high-rate performance as delivering reversible capacities of 480 mA h g−1 at 100 mA g−1 and 290 mA h g−1 at 2000 mA g−1. In addition, the specific capacity can still maintain 320 mA h g−1 at 500 mA g−1 even after 900 cycles, showing the outstanding cycling stability. The inactive metal Co and one-dimensional N-doped carbon nanofibers synergistically promote the electrochemical performance of the Sn-based anode by inhibiting the aggregation of the nanoparticles and buffering volume variation during lithiation/delithiation process.

Non-smooth carbon coating porous SnO2 quasi-nanocubes towards high lithium storage

Design and construction of versatile nanostructured SnO2/C composites is still an efficient strategy for developing advanced SnO2-based lithium-ion battery anode materials. Generally, the composite way of carbon and SnO2 in SnO2/C is that the nanostructured SnO2 is coated by a smooth carbon coating. It is believed that if the SnO2 is coated by a characteristically non-smooth three-dimensional (3D) carbon coating rather than smooth carbon coating, the lithium storage properties of SnO2/C would be greatly improved owing to the sufficient free space and larger surface area of 3D structure. However, the SnO2/C composites with a 3D carbon coating are rarely reported because of the difficulty in preparation. In this work, an interestingly nanostructured SnO2/C composite (SnO2@C) with a uniquely non-smooth carbon coating has been prepared via a carefully devised strategy, which consists of uniquely 3D jagged carbon coating porous SnO2 quasi-nanocubes. Thus unique architecture offers SnO2@C enhanced electrochemical kinetics and superior structural stability when served as a lithium-ion battery anode material. Consequently, the SnO2@C displays extraordinaire cycle performance and outstanding rate capability, releasing capacity of 1089.5 mAh g−1 at 200 mA g−1 after even 400 cycles, as well as 479.2 mAh g−1 even at 3000 mA g−1.

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.