Explore the vast range of titles available.

Micro/nano-Si flakes were obtained by a facile approach of reaction ball milling self-assembly, and then, a Si@C anode material with a carbon content of 17.7wt% was synthesized by combining the Si flakes with phenol formaldehyde resin. It was revealed that the micro/nano-Si flakes inherited the advantages of both nano-Si and bulk Si, showing not only a considerable surface area of 65.6 m 2  g −1 but also a high tap density of 0.66 g cm −3 . The Si@C anode showed outstanding electrochemical performance, particularly its high volumetric capacity, due to the formation of dual-layer SiO x /C film on the micro/nano-Si. The Si@C anode delivered a gravimetric/volumetric capacity as high as 1721.9 mAh g −1 /1239.8 mAh cm −3 at 0.05 A g −1 and preserved a large gravimetric/volumetric capacity of 1028.7 mAh g −1 /740.7 mAh cm −3 at 2.0 A g −1 . It retained 92.0% of its initial capacity after 200 cycles at 0.5 A g −1 .

To solve the problem of extremely low washing efficiency of graphite oxide (GO), an efficient method is successfully developed to prepare few-layer graphene powder, which is a key raw material for the preparation of high tap-density graphene (HTDG) anode materials. HTDG anode powder with the tap density of 0.68 kg L−1 can be obtained. The characterization results demonstrate that this efficient method is feasible for synthesizing the few-layer graphene and HTDG anode materials. The results of electrochemical measurements show that the HTDG anode materials display satisfactory electrochemical performance. The reversible capacity up to 326.3 mAh g−1 and excellent cyclic and rate performance, which are all better than those of commercial hard carbon materials, are achieved based on HTDG anode materials in a potential range of 0–1.5 V (vs. Li/Li+). Additionally, the acquired HTDG anode materials are also applied in soft-packaged Li-ion capacitors (LICs). The capacity retention of the LICs with operating voltage of 1.5–4.2 V can reach 90.4% after 1500 cycles at 1 C rate. The devices also possess the good rate performance: the capacity can maintain about 90% at 10 C, 86% at 15 C, 84% at 20 C, 79% at 40 C, 75% at 60 C, 70% at 80 C, and 56% at 100 C.

A facile way of synthesizing LiFePO4/C with high tap density was introduced. LiFePO4/C composites were synthesized by a combination of wet ball milling, spray drying, and carbothermal reduction technology using inexpensive FePO4. The effect of sphericity of secondary microsphere on electrochemical properties and tap density of LiFePO4/C composite was systematically investigated. The sphericity of the secondary microsphere is controlled by particle size of primary particle with varying the ball grinding time. The composites were characterized in detail by X-ray diffraction (XRD), scanning electron microscopy (SEM), and tap density testing. The particle size of primary particle can effectively influence the sphericity of the secondary microsphere, and consequently change the electrochemical properties and tap density of LiFePO4/C. The optimum LiFePO4/C with high tap density of 1.68 g cm−3 contains 2.1 wt% carbon and shows an excellent rate capability and cycle performance, with the initial discharge capacities of 164.0, 159.6, 154.9, 148.3, and 138.3 mAh g−1 at 0.2 C, 0.5 C, 1 C, 2 C, and 5 C. The good electrochemical properties are attributed to the smaller particle, uniform primary particle size distribution, and the uniform carbon coating. The high tap density of LiFePO4/C composite is attributed to the better sphericity of secondary microsphere. With the primary particle size decreasing, the secondary microsphere sphericity is better.

A series of spherical LiNi0.8Co0.15Ti0.05O2 cathode materials were synthesized through co-oxidation-controlled crystallization method followed by solid-state reaction at different calcination temperatures under oxygen flowing. The crystal structure and particles morphology of the as-prepared powders were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. All samples correspond to the layered α-NaFeO2 structure with R-3m space group. The LiNi0.8Co0.15Ti0.05O2 prepared at 800 °C presents a better hexagonal ordering structure and better spherical particles and possesses a high tap density of 3.22 g cm−3. Meanwhile, the NCT-2 sample exhibits an advanced electrochemical performance with an initial discharge capacity of 174.2 mAh g−1 and capacity retention of 86.7 % after 30 cycles at 0.2 C.

Limited by the size of microelectronics, as well as the space of electrical vehicles, there are tremendous demands for lithium-ion batteries with high volumetric energy densities. Current lithium-ion batteries, however, adopt graphite-based anodes with low tap density and gravimetric capacity, resulting in poor volumetric performance metric. Here, by encapsulating nanoparticles of metallic tin in mechanically robust graphene tubes, we show tin anodes with high volumetric and gravimetric capacities, high rate performance, and long cycling life. Pairing with a commercial cathode material LiNi 0.6 Mn 0.2 Co 0.2 O 2 , full cells exhibit a gravimetric and volumetric energy density of 590 W h Kg −1 and 1,252 W h L −1 , respectively, the latter of which doubles that of the cell based on graphite anodes. This work provides an effective route towards lithium-ion batteries with high energy density for a broad range of applications. Here the authors report a tin anode design by encapsulating tin nanoparticles in graphene tubes. The design exhibits high capacity, good rate performance and cycling stability. Pairing with NMC, the full cell delivers a volumetric energy density twice as high as that for the commercial cell.

A low-cost and facile method for synthesizing micro-size lithium titanium oxide, micro-size Li4Ti5O12 (MS-LTO), has been proposed in this study. The MS-LTO with a high tap density of 1.38 g cm−3 is prepared from synthesis-grade TiOSO4 through hydrolysis followed by calcination of obtained TiO2 with LiOH · H2O. The parameters of pH, temperature, concentration, etc. are optimized for preparing the precursor H2TiO3. The morphology, size, and structure of H2TiO3, TiO2, and MS-LTO are carefully characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The electrochemical performances of the as-prepared MS-LTO deliver a reversible capacity of 171 mA · h g−1 at 0.1 C and show a good rate capability by maintaining 47 % of the capacity at 5 C (vs. 0.1 C), as well as remarkable cycling stability without capacity fading after 100 cycles at both 1 and 2 C. This as-prepared MS-LTO shows a potential application in lithium-ion batteries which can be utilized in the next-generation electric vehicles and hybrid electric vehicles. Furthermore, the strategy for synthesizing MS-LTO from production-level TiOSO4 · xH2SO4 · xH2O proposed here provides a facile method for preparing lithium-ion anode materials.

To achieve both high gravimetric and volumetric energy densities of lithium–sulfur (Li–S) batteries, it is essential yet challenging to develop low‐porosity dense electrodes along with diminishment of the electrolyte and other lightweight inactive components. Herein, a compact TiO2@VN heterostructure with high true density (5.01 g cm–3) is proposed crafted by ingenious selective nitridation, serving as carbon‐free dual‐capable hosts for both sulfur and lithium. As a heavy S host, the interface‐engineered heterostructure integrates adsorptive TiO2 with high conductive VN and concurrently yields a built‐in electric field for charge‐redistribution at the TiO2/VN interfaces with enlarged active locations for trapping‐migration‐conversion of polysulfides. Thus‐fabricated TiO2@VN–S composite harnessing high tap‐density favors constructing dense cathodes (≈1.7 g cm–3) with low porosity (<30 vol%), exhibiting dual‐boosted cathode‐level peak volumetric‐/gravimetric‐energy‐densities nearly 1700 Wh L−1cathode/1000 Wh kg−1cathode at sulfur loading of 4.2 mg cm−2 and prominent areal capacity (6.7 mAh cm−2) at 7.6 mg cm−2 with reduced electrolyte (<10 µL mg−1sulfur). Particular lithiophilicity of the TiO2@VN is demonstrated as Li host to uniformly tune Li nucleation with restrained dendrite growth, consequently bestowing the assembled full‐cell with high electrode‐level volumetric/gravimetric‐energy‐density beyond 950 Wh L−1cathode+anode/560 Wh kg−1cathode+anode at 3.6 mg cm−2 sulfur loading alongside limited lithium excess (≈50%). A high‐density fibrous TiO2@VN heterostructure mediator with built‐in electric fields is constructed via an ingenious selective nitridation from biotemplate‐derived twinborn hybrid titanium/vanadium oxide fibers, which can synchronously serve as carbon‐free, dual‐capable hosts of both sulfur and lithium for practical high‐energy‐density Li–S full batteries.

Increasing the energy density of conventional lithium‐ion batteries (LIBs) is important for satisfying the demands of electric vehicles and advanced electronics. Silicon is considered as one of the most‐promising anodes to replace the traditional graphite anode for the realization of high‐energy LIBs due to its extremely high theoretical capacity, although its severe volume changes during lithiation/delithiation have led to a big challenge for practical application. In contrast, the co‐utilization of Si and graphite has been well recognized as one of the preferred strategies for commercialization in the near future. In this review, we focus on different carbonaceous additives, such as carbon nanotubes, reduced graphene oxide, and pyrolyzed carbon derived from precursors such as pitch, sugars, heteroatom polymers, and so forth, which play an important role in constructing micrometer‐sized hierarchical structures of silicon/graphite/carbon (Si/G/C) composites and tailoring the morphology and surface with good structural stability, good adhesion, high electrical conductivity, high tap density, and good interface chemistry to achieve high capacity and long cycling stability simultaneously. We first discuss the importance and challenge of the co‐utilization of Si and graphite. Then, we carefully review and compare the improved effects of various types of carbonaceous materials and their associated structures on the electrochemical performance of Si/G/C composites. We also review the diverse synthesis techniques and treatment methods, which are also significant factors for optimizing Si/G/C composites. Finally, we provide a pertinent evaluation of these forms of carbon according to their suitability for commercialization. We also make far‐ranging suggestions with regard to the selection of proper carbonaceous materials and the design of Si/G/C composites for further development. The co‐utilization of Si and graphite has emerged as the most practical anode for high‐energy lithium‐ion batteries, but there are still significant challenges. The carbon additives play important roles in integrating the Si and graphite with tailored structure, morphology, and surface, and are discussed along with the synthesis methods and strategies to provide insights for further development and commercialization of Silicon/Graphite/Carbon (Si/G/C) anodes in the future.

Nanoporous silicon is a promising anode material for high energy density batteries due to its high cycling stability and high tap density compared to other nanostructured anode materials. However, the high cost of synthesis and low yield of nanoporous silicon limit its practical application. Here, we develop a scalable, low-cost top-down process of controlled oxidation of Mg 2 Si in the air, followed by HCl removal of MgO to generate nanoporous silicon without the use of HF. By controlling the synthesis conditions, the oxygen content, grain size and yield of the porous silicon are simultaneously optimized from commercial standpoints. In situ environmental transmission electron microscopy reveals the reaction mechanism; the Mg 2 Si microparticle reacts with O 2 to form MgO and Si, while preventing SiO 2 formation. Owing to the low oxygen content and microscale secondary structure, the nanoporous silicon delivers a higher initial reversible capacity and initial Coulombic efficiency compared to commercial Si nanoparticles (3,033 mAh/g vs. 2,418 mAh/g, 84.3% vs. 73.1%). Synthesis is highly scalable, and a yield of 90.4% is achieved for the porous Si nanostructure with the capability to make an excess of 10 g per batch. Our synthetic nanoporous silicon is promising for practical applications in next generation lithium-ion batteries.

Compared to nanostructured Si/C materials, micro-sized Si/C anodes for lithium-ion batteries (LIBs) have gained significant attention in recent years due to their higher volumetric energy density, reduced side reactions and low costs. However, they suffer from more severe volume expansion effects, making the construction of stable micro-sized Si/C anode materials crucial. In this study, we proposed a simple wet chemistry method to obtain porous micro-sized silicon (μP-Si) from waste AlSi alloys. Then, the μP-Si@carbon nanotubes (CNT)@C composite anode with high tap density was prepared by wrapping with CNT and coated with polyvinylpyrrolidone (PVP)-derived carbon. Electrochemical tests and finite element (FEM) simulations revealed that the introduction of CNTs and PVP-derived carbon synergistically optimize the stability and overall performance of the μP-Si electrode via construction of tough composite interface networks. As an anode material for LIBs, the μP-Si@CNT@C electrode exhibits boosted reversible capacity (∼ 3500 mAh·g −1 at 0.2 A·g −1 ), lifetime and rate performance compared to pure μP-Si. Further full cell assembly and testing also indicates that μP-Si@CNT@C is a highly promising anode, with potential applications in future advanced LIBs. It is expected that this work can provide valuable insights for the development of micro-sized Si-based anode materials for high-energy-density LIBs.