Cycling Rate Research Articles

Long‐Durable Potassium Ion Batteries Enabled by Medium‐Entropy Lattice Engineering on Prussian Blue Analogues Cathodes

AbstractGiven their structural merits and electrochemical benefits, Prussian blue analogues (PBAs) hold great promise as cathode materials for potassium ion batteries (PIBs). However, these cathodes face formidable hurdles by structural failure and poor rate capability, primarily resulting from significant volumetric changes and sluggish kinetics during repeated intercalation/deintercalation of bulky K+ ions. Theoretically, the study reveals explicitly that quaternary medium‐entropy PBAs (Q‐ME‐PBAs), composed of Fe, Ni, Co, and Cu, demonstrate minimal lattice volume variations and low diffusion barriers during K+ ion interactions. This endows Q‐ME‐PBA with favorable ability to induce significant 3D lattice distortion, enabling the material to endure structural alterations during K+ ion movements and reinforce phase stability. Consequently, leveraging the structural and compositional advantages, the resultant Q‐ME‐PBAs cathode showcases exceptional cycling performance, maintaining over 90% capacity retention after 300 cycles at 0.25 C with a high initial coulombic efficiency of 94.4% and retaining 74.7% capacity even after an ultra‐long 10 000 cycles at 3.75 C over 147 days. Notably, full cells paired with hard carbon and graphite anodes show outstanding cycling stability and rate capability. This study charts fresh design directions for crafting high‐performance and durable cathodes through medium‐entropy lattice engineering for advanced PIBs.

Zr4+-doped sodium manganese oxide: enhanced electrochemical performance as a cathode in sodium ion batteries.

Sodium manganese oxides are regarded as a valuable class of cathode materials for sodium-ion batteries. By varying the stoichiometry of Na, Mn and O, it is possible to obtain layered, tunnel and spinel type structures, which can withstand the electrochemically-triggered sodiation-desodiation process. In this work, we report the electrochemical performance of Na4Mn2O5, a sodium-rich manganese oxide, which has been previously reported to suffer from structural instability due to the Jahn-Teller distortion of the Mn3+ ion. It was observed that the Na4Mn2-xZrxO5 (x = 0.1) cathode delivered a discharge capacity of ∼203 mA h g-1 post 250 cycles with a capacity retention rate of ∼82.8% on doping with Zr4+ ions. The improvement in cycling ability and rate capability is attributed to the enhanced structural stability and improved electronic conduction brought about by the substitution of Mn3+ by Zr4+ in Na4Mn2O5. Density functional theory-based studies were conducted, which adequately support the obtained results.

Randomized, Phase III Trial of Mixed Formulation of Fosrolapitant and Palonosetron (HR20013) in Preventing Cisplatin-Based Highly Emetogenic Chemotherapy-Induced Nausea and Vomiting: PROFIT.

Mixed formulation of fosrolapitant and palonosetron (PALO), HR20013, is a novel fixed-dose intravenous antiemetic combination that could simultaneously antagonize neurokinin-1 and 5-hydroxytryptamine-3 receptors. This study was designed to evaluate the efficacy and safety of HR20013 plus dexamethasone (DEX) versus fosaprepitant (FAPR) plus PALO + DEX for preventing chemotherapy-induced nausea and vomiting (CINV) in patients receiving highly emetogenic chemotherapy (HEC). This is a noninferiority study. Chemotherapy-naïve patients were randomly assigned 1:1 to receive HR20013 (day 1) or FAPR + PALO (day 1) before each cycle of cisplatin-based HEC (two cycles in total), together with oral DEX (day 1-4). The primary end point was overall (0-120 hours) complete response (CR; no vomiting/no rescue therapy) rate in cycle 1. The key secondary end point was CR rate at the beyond delayed phase (120-168 hours) in cycle 1. Three hundred seventy-three patients were enrolled to receive HR20013 + DEX and 377 to FAPR + PALO + DEX. The overall CR rate in cycle 1 was 77.7% for HR20013 + DEX and 78.2% for FAPR + PALO + DEX (difference = -0.9% [95% CI, -6.7 to 5.0]; one-sided P < .01), demonstrating that HR20013 + DEX was noninferior to FAPR + PALO + DEX. The superiority of HR20013 + DEX over FAPR + PALO + DEX in CR rate at the beyond delayed phase in cycle 1 was not met (90.3% v 86.5%; two-sided P = .11). In cycle 2, HR20013 + DEX showed greater proportions of patients reporting no impact on daily life at the delayed (24-120 hours) and beyond delayed phases compared with FAPR + PALO + DEX. The incidences of treatment-related adverse events were 35.7% during cycle 1 and 42.1% during entire study for HR20013 + DEX, versus 38.2% and 44.0% for FAPR + PALO + DEX. HR20013 + DEX was noninferior to FAPR + PALO + DEX for preventing HEC-CINV and well tolerated, with the potential to reduce the impact of CINV on daily life.

Experimental and modeling insights into the kinetics of calcium looping CO2 capture process: Assessment of limestone treatment

This investigation aimed to offer a precise and detailed understanding of the intricate mechanisms governing the rapid and diffusion stages of carbonation within the calcium looping process, while also exploring the effects of treatment on mineral limestone (Raw limestone) as the primary sorbent for CO2 capture. Two modified samples treated with acetic acid (Acidified limestone) and hydrophobic silica nanoparticles (Silica-mixed limestone), were analyzed to provide deeper insights into the kinetics of the slow and fast stages of the carbonation reaction. The Acidified limestone had a significant influence on the carbonation conversion rates of both the rapid and slow stages, resulting in a notable enhancement in conversion efficiency. Notably, the carbonation conversion rates in the 20th cycle were measured as 0.201, 0.348, and 0.231 for the Raw, Acidified, and Silica-mixed limestones, respectively. An increase in the number of reaction cycles led to an increased percentage contribution of the diffusion stage, a decrease in transition time and consequently, a reduction in the overall carbonation conversion rate. Specifically, the share percentage of carbonation conversion for the diffusion stage in the 20th cycle was determined as 31.55%, 34.88%, and 30.36% for the Raw, Acidified, and Silica-mixed limestones, respectively. The results obtained from the modeling application demonstrated a reduction in the maximum absolute error with an increase in the reaction cycles. Additionally, the prediction results indicated that the carbonation conversion rates for the Raw and Acidified limestones in the 100th cycle were determined to be 0.07 and 0.12, respectively.

Flower-like graphitic carbon derived from biomass for anode of potassium ion battery

The conventional graphite anode for potassium ion batteries (PIBs) can be structurally disrupted by intercalation of potassium ion with a large radius, resulting in the poor cycling stability and rate capability. Here an architecture of flower-like graphitic carbon (FLGC) derived from biomass is designed. As the anode for PIBs, FLGC achieves the stable performance and high-rate capability because of numerous mesopores, intrinsic defects, and a large interlayer spacing. FLGC presents a stable cycling performance (171mAh g−1 after 1700 cycles at 500 mA g−1 with a capacity retention of 79.2 %) and a high potassium storage capacity (301mAh g−1 at 100 mA g−1), in addition to low charge/discharge plateaus (0.35 V for charge and 0.12 V for discharge). More importantly, the mechanism for potassium storage and influence of intrinsic defects on the electrochemical performance are investigated. This study offers a novel design for graphitic structures, which is important for PIBs.

Facile one-pot synthesis of Bi2S3 nanorod @ N, S co-doped carbon composite for high performance lithium ion batteries

Bismuth sulfide is favoured in lithium ion batteries due to its high specific capacity of 625 mAh/g. However, the Bi2S3 anode faces severe volume expansion problems during the lithium intercalation process, resulting in continuous electrode fragmentation and rapid degradation of lithium storage performance. In this study, Bi2S3 nanorod@N, S co-doped carbon composite prepared by a simple sintering method was used as the anode material for lithium ion batteries. 1D Bi2S3 nanorods with a length of 1 μm and a diameter of 50 nm were loaded in situ on 2D N, S co-doped carbon nanosheets. This unique structure can not only alleviate the volume change of bismuth sulfide, but also effectively shorten the diffusion distance of lithium ions, thereby improving the cycling stability and rate capability at the same time. The discharge capacity of Bi2S3@N, SC remained at 583.4 mAh g –1 after 400 cycles at 0.5 A g–1. Even at a high current density of 2 A/g, the discharge capacity of Bi2S3@N, SC still reached 374.3 mAh g –1. This simple method also can be extended to the preparation of other metal sulfide composites.

High porosity, excellent mechanical strength, interpenetrating network-reinforced double network regenerated cellulose separators for lithium-ion battery

Cellulose material is emerging as a promising alternative to polyolefin separators in lithium-ion batteries (LIBs) due to its wide availability, electrolyte wettability and thermal stability. Based on the non-solvent induced phase separation, dissolving and regenerating the cellulose material by environmentally friendly solvents and non-solvent enables the efficient and pollution-free preparation of porous regenerated cellulose separator (RCS), greatly expanding their application potential in LIBs. However, the mechanical strength of pure RCS still hardly satisfactory, due to the weak intermolecular bonding and loose porous structure. Therefore, this study introduced an acrylic acid/acrylamide (AA/AM) polymer cross-linking system forming an interpenetrating network with the cellulose framework to produce a double network regenerated cellulose separator (DN-RCS) with high mechanical strength and high porosity. At meantime, the special functional group on AA/AM can influence the transport process of Li+ and PF6− in the electrolyte, helping to form a stable interface on the electrolyte/lithium anode surface to reduce the formation of lithium dendrites. The results showed that DN-RCS possessed excellent mechanical strength and porosity compared to RCS. The high ionic conductivity of DN-RCS (1.03 mS cm−1) enabled the assembled cell with excellent cycling stability (90.8 % at 0.5C for 100 cycles) and rate performance (65.2 % at 5C). This work provides a further feasible strategy for the preparation of a high-performance cellulose-based separator.

Mo–O–Sn Bond Boosting Kinetics of MoO2−xSnO2/Sn Anode for High‐Performance Li‐ion Batteries

Obtaining a robust electrode composed of Sn‐based metal oxides and carbonaceous matrix through nanoscale structure engineering is essential for effectively improving Li‐ion batteries' electrochemical performance and stability. Herein, we report a bimetallic MoO2‐xSnO2/Sn nanoparticles uniformly anchored on N, S co‐doped graphene nanosheets (MoO2‐xSnO2/Sn@NSG) as an anode electrode for Li‐ion battery via a one‐step hydrothermal and thermal treatment approach. In the MoO2‐xSnO2/Sn nanocomposite, the generated Sn‐O‐Mo bond can modulate the electronic and composition structures to improve the intrinsic conductivity of SnO2 and reinforce the structural stability during cycles. Moreover, featuring excellent electronic conductivity via coupling of MoO2‐xSnO2/Sn and hierarchical NBG matrix, the MoO2‐xSnO2/Sn@NSG electrode possesses ultrafast electrochemical kinetics and superior long‐term cycling stability and rate capability. Additionally, the hierarchical MoO2‐2SnO2/Sn@NSG can suppress the aggregation and accommodate the volume variations of active substances, thereby providing more lithium storage sites. Consequently, the optimized MoO2‐2SnO2/Sn@NSG anode exhibits a high reversible capacity of 904 mA h g‐1 at 0.2 A g‐1 and excellent cycling performance with the reversible capacity of 456 mAh g‐1 at 1 A g‐1 over 600 cycles. The universal synthesis technology of bimetallic oxide anodes for advanced LIBs may provide vital guidance in designing high‐performance energy‐storage materials.

Power increase potential of coal-fired power plant assisted by the heat release of the thermal energy storage system: Restrictions and thermodynamic performance

The integration of a thermal energy storage (TES) system is an effective way to improve the load cycling rate of coal-fired power plants (CFPPs). To evaluate the power increase potential and thermodynamic performance of CFPP supplied by heat release of the molten salt TES system, eight discharging modes for CFPP integrated with the TES system including steam injection, heater bypass, and additional turbine schemes were comparatively evaluated. The system simulation models of the integrated systems were developed and the thermodynamic performance of the proposed system were evaluated. Results show that the mode SI-HPT (high-pressure turbine steam injection) has the largest output power increase of 25.00 % under the benchmark condition of 75%THA, but the mode HB-LPH (low-pressure heater bypass) shows a very low output power increase of 2.08 %. Moreover, the power generation efficiency is changed by the external heat source through a change in the average heat absorption temperature of the Rankine cycle and the internal irreversibility of the steam/water cycle. Under the typical benchmark discharging condition of 75%THA, the power generation efficiency of the turbine in mode SI-LPT (low-pressure turbine steam injection) can be reduced from 47.41 % to 44.15 %, but it can be increased from 47.41 % to 48.86 % in mode SI-HPT. When the temperature ranges of the TES system are above 600 °C and below 450 °C, the modes SI-HPT and SI-LPT obtain the optimal comprehensive performance, respectively. This study can provide the scientific guidance for retrofit for CFPP to achieve efficient and flexible design.

Fluorine-doped carbon coating of LiFe0.5Mn0.5PO4 enabling high-rate and long-lifespan cathode for lithium-ion batteries

The limited electron and ionic conductivity, along with the sluggish kinetics caused by the Jahn-Teller effect of Mn3+, impose constraints on the electrochemical performance of LiFexMn1-xPO4. Herein, the surface of LiFe0.5Mn0.5PO4 (LFMP) is modified with a F-doped carbon using the solvothermal and calcination methods. The incorporation of F-doped carbon coating, along with the formation of interfacial F-Li, F-Fe and F-Mn bonds between the carbon layer and LFMP nanoparticles, significantly mitigates charge transfer resistance, facilitates rapid electron transfer, as well as enhances Li+ diffusion kinetics. The LFMP@C-F2 cathode prepared in this study exhibits an unexceptionable capacity retention of 90.5 % after 300 cycles at a low rate of 0.2C and a capacity retention of 78.8 % over 1000 cycles at a high rate of 1C. When incorporated into the solid battery configuration (Li/PEO-LATP CSE/LFMP@C-F2), it exhibits an initial discharge specific capacity of 148 mAh g−1 and maintains a capacity retention of 85.8 % after 60 cycles at 0.1C, thereby offering an innovative approach to enhance the performance of LFMP in terms of cycling stability and rate capacity in lithium-ion batteries, as well as to apply LFMP into solid-state lithium batteries.

Ambient-pressure relithiation of spent LiFePO4 using alkaline solutions enables direct regeneration of lithium-ion battery cathodes

Lithium iron phosphate (LiFePO4) is widely recognized for its cost-effectiveness in manufacturing and high safety during usage, making it a favored choice for electric vehicles and energy storage stations. Nevertheless, the development of efficient and low-cost recycling methods has emerged as an urgent priority due to the economic and environmental benefits associated with it. Here, the present study successfully demonstrates the ambient-pressure relithiation of lithium-deficient LiFePO4 particles in alkaline solutions. Specifically, the incorporation of reductive sodium nitrite with lower redox potential in the alkaline environment spontaneously repairs the compositional and structural defects, facilitating effective lithium-ion insertion back into the original site. Consequently, the short-term annealing step promotes the formation of more thermodynamically stable particles, resulting in enhanced cycling stability and rate capability comparable to that of the pristine materials. The regenerated LiFePO4 cathode exhibits improved electrochemical performance in terms of long-term cyclability, high-rate properties and reduced polarization (a high retention of 93 % after 1000 cycles at 5C). The findings of this study suggest the significant potential for utilizing various reductants in an alkaline environment to achieve ambient-pressure relithiation, thereby facilitating the recycling and remanufacturing of spent lithium-ion cathode materials.

Template-free synthesis of hollow titanium dioxide microspheres and amorphous titanium dioxide microspheres with superior lithium and sodium storage performance

Hierarchical hollow TiO2 microspheres (H-TiO2) and amorphous solid TiO2 microspheres (A-TiO2) were synthesized using a template-free method. Initially, quasi-monodisperse solid TiO2 microspheres (A-TiO2) were obtained by controlled thermal hydrolysis of titanium sulfate, forming aggregates of amorphous particles, followed by solvothermal treatment to convert the solid structure into a hollow and crystalline H-TiO2 structure. SEM and TEM images revealed that the morphological evolution from A-TiO2 to H-TiO2 conforms precisely to the inside-out Ostwald ripening mechanism. The unique hollow layered structure endows H-TiO2 with a large specific surface area of 93.3 m2/g and a rich porous structure. When used as an anode material for LIBs and SIBs, H-TiO2 exhibits superior cycling stability and rate performance compared to A-TiO2. For LIBs, H-TiO2 achieves a reversible capacity of 342.2 mA h g−1 at a 0.2C charge/discharge rate and retains unprecedented long-term stability at high current densities (258.5 mA h g−1 after 1000 cycles at 5C and 220.4 mA h g−1 after 1000 cycles at 10C). For SIBs, H-TiO2 exhibits a reversible capacity of 271.7 mA h g−1 at 0.2C, with specific capacities of 173.4 mA h g−1 after 1000 cycles at 1C and 101.4 mA h g−1 after 2000 cycles at 5C. Furthermore, kinetic calculations demonstrate that H-TiO2 possesses higher Li+ and Na+ diffusion rates, adsorption capacities, and conductivity, further explaining its excellent electrochemical performance.

Design of large-spacing, high-stability PANI-NixV2O5 nanobelts as cathode for aqueous zinc-ion batteries using an organic-inorganic co-embedding strategy

Aqueous zinc-ion batteries (AZIBs), distinguished by their high safety and cost-effectiveness, hold significant promise for grid-level energy storage systems. However, the strong interactions between zinc ions and the host lattice of materials lead to suboptimal cycling stability and rate performance. To address this, we present a novel superlattice structure incorporating conductive polymer (PANI) and metal cation (Ni2+) double interlayers, which can be utilized as cathodes for AZIBs. The incorporation of the conductive host polymer polyaniline (PANI) reduces the valence state of vanadium, enhances the electrical conductivity, and effectively expands the channels for zinc ion insertion. Additionally, metal cations (Ni2+) can effectively induce the synergistic interactions with zinc ions, thereby mitigating the electrostatic interactions with the V2O5 host. Consequently, the assembled Zn//PANI-NixV2O5 (PNV) battery exhibits a specific capacity of up to 470 mAh g−1 at 0.1 A g−1, and retains 89.5 % of its capacity after 1000 cycles at 5 A g−1.

Cross-Linked Polyamide-Integrated Argyrodite Li6PS5Cl for All-Solid-State Lithium Metal Batterie.

Lithium dendrite growth has become a significant barrier to realizing high-performance all-solid-state lithium metal batteries. Herein, an effective approach is presented to address this challenge through interphase engineering by using a cross-linked polyamide (negative electrostatic potential) that is chemically anchored to the surface of Li6PS5Cl (positive electrostatic potential). This method improves contact between electrolyte particles and strategically modifies the local electronic structure at the grain boundary. This innovation effectively suppresses lithium dendrite formation and enhances the overall interface stability. As a result, the critical current density of the Li6PS5Cl sulfide electrolyte is dramatically boosted from 0.4 to 1.6mAcm-2, representing a remarkable fourfold improvement. Moreover, Li-Li symmetric batteries demonstrate exceptional stability, enduring over 10,000 h of consistent Li+ deposition/stripping at a high areal capacity of 3mAhcm-2. Impressively Li-LiNi0.89Mn0.055Co0.055O2 full cells exhibited outstanding cycle stability and rate performance, maintaining over 80% capacity retention after 750 cycles at a demanding 1C rate. Pouch cells produced using dry-process electrodes demonstrate strong potential for commercialization. The interphase engineering strategy offers a promising solution to the persistent challenge of dendrite growth, enabling the full realization of sulfide electrolytes' capabilities in next-generation battery technologies.

Machining characteristics and optimization of TC4 alloy by mixed gas atomization discharge ablation milling (MA-DAM)

A method using mixed gas atomization discharge ablation milling (MA-DAM) for machining titanium alloys was proposed to address the processing efficiency and quality issues in conventional near-dry electrical discharge milling (N-EDM). By analyzing the discharge waveform, a pulse discharge physical model was established to reveal the machining mechanisms of N-EDM and MA-DAM. It was found that the latter had a unique ablation process compared to the former, resulting in better machining performance. The results of oxygen concentration experiments showed that compared to N-EDM, MA-DAM improved the material removal rate by 55.6 % and reduced the relative electrode wear rate by 50 %, but increased the width of the overcut by approximately 10 % and the average roughness by approximately 17 %. Orthogonal experiments and variance analysis were conducted to study the effects of the current, duty cycle, gas pressure, and atomization rate on the machining performance indicators. Finally, grey relational analysis was used for the multi-objective optimization of machining parameters to obtain the optimal process configuration for MA-DAM, which was validated through experiments.

Degradation evaluation on the mechanical properties of composite electrode through an integrated phase field and continuum simulation

The electrochemical degradation phenomena in lithium-ion batteries imply that the mechanical properties of a composite electrode may deteriorate during cycling, however, there are still lack of detail information on their direct correlations. Here, we proposed an integrated phase field-continuum simulation method to track the process of mechanical degradation. Based on scanning electron microscope images of a composite electrode, a representative volume element microstructural model was constructed and the damage evaluations caused by lithiation and delithiation were estimated though the phase-field method. Then a subsequent continuum mechanical model was performed on meso-structures with damage to evaluate their mechanical properties. The results show that damage primarily occurs during the initial cycle, and decreasing particle sizes and the cycling rate can effectively mitigate damage. This work bridges the relationship between the particle damage and mechanical properties of composite electrodes, and thus, provides an important insight on the stress evaluation and optimal design in service.

Synergistic Effect and Mechanism of Combined Astaxanthin and Curcumin Administration on Ovarian Function in PCOS Mice

ABSTRACTTo investigate the synergistic effect of astaxanthin and curcumin on ovarian function in polycystic ovary syndrome (PCOS) mice and to elucidate the underlying mechanisms, fifty 4‐week‐old female mice were randomly divided into five groups: (i) normal control group; (ii) PCOS model group; (iii) PCOS + astaxanthin group; (iv) PCOS + curcumin group; and (v) PCOS + astaxanthin–curcumin. Throughout the study, various parameters were meticulously evaluated, including serum levels of key reproductive hormones (testosterone (T), estradiol (E2), follicle‐stimulating hormone (FSH), luteinizing hormone (LH), and anti‐Müllerian hormone (AMH)), as well as monitoring alterations in the estrous cycle, follicle development, and ovulation rates. Additionally, markers of oxidative stress and inflammation were measured. Findings revealed that PCOS mice exhibited disordered estrous cycle, polycystic ovarian morphologies, abnormal serum reproductive hormones and lipid metabolism, heightened oxidative stress, and augmented inflammatory responses. Notably, upon administration of the combined astaxanthin and curcumin, PCOS mice exhibited significant improvements in their estrous cyclicity and ovarian histology. The treatment led to a significant reduction in serum total cholesterol (TC) levels and normalization of T, E2, FSH, LH, and AMH levels. Moreover, there was a marked decrease in the levels of serum reactive oxygen species (ROS) and malondialdehyde (MDA), indicating attenuation of oxidative stress. Concurrently, the activity of the antioxidant enzyme catalase (CAT) significantly increased, while proinflammatory cytokines interferon‐γ (IFN‐γ) and interleukin‐6 (IL‐6) in the ovarian tissue were notably decreased. The combined treatment also resulted in a substantial increase in the number of ova and a significant decline in the rate of abnormal ova, with these therapeutic effects proving more effective compared to either astaxanthin or curcumin alone. In conclusion, the co‐administration of astaxanthin and curcumin demonstrated a remarkable effect in improving abnormal lipid metabolism and restoring reproductive endocrine functions in PCOS mice. Furthermore, it effectively mitigated systemic and local oxidative stress and chronic inflammatory injury, thereby promoting follicular growth and enhancing ovulatory function in the context of PCOS.

Design of an LiF-rich interface layer using high-concentration fluoroethylene carbonate and lithium bis(fluorosulfonyl)imide (LiFSI) to stabilize Li metal batteries.

The development of high-energy-density Li metal batteries is limited by the uncontrollable growth of Li dendrites and an unstable Li/electrolyte interface during long-term Li plating/stripping. In this work, using high-concentration fluoroethylene carbonate (FEC) electrolyte, an LiF-rich interface layer was generated on the Li metal surface. This LiF-rich interface layer could effectively inactivate the high reactivity of the Li metal surface and suppress lithium dendrite growth, forming a uniform and dense structure at the Li/electrolyte interface to stabilize Li metal batteries. Owing to the enhanced interface stability offered by the high-concentration FEC electrolyte with LiFSI additive, the Li‖LiFePO4 cell presented high capacity retention (89.1%) after 200 cycles at 1C (165 mA g-1) and retained over 133.7 mA h g-1 at 10C rate, whereas only 115.0 mA h g-1 was achieved in the traditional carbonate ester electrolyte. The results show an obvious improvement in the cycle performance and rate capability of Li metal batteries containing a high-concentration FEC electrolyte with LiFSI as an additive.

Novel Q-Carbon Anodes for Sodium-Ion Batteries

The lack of a standard anode for sodium-ion batteries (SIBs) has greatly hindered their applications. Herein, we show that a novel phase of carbon, namely Q-carbon, is an effective anode material for sodium-ion batteries. The Q-carbon, which is a metastable phase of carbon consisting of about 80% sp3- and 20% sp2-bonded carbon, is synthesized by nonequilibrium pulsed laser annealing and arc-discharge methods. Two types of Q-carbons, Q1 and Q2, were evaluated as anode material for SIBs. Q1 had a slow quench and was used as the control, whereas Q2 was Q-carbon with a rapid quenching. Q1 exhibits a high initial columbic efficiency of 81% and a low-capacity retention of less than 60%, whereas Q2 has a low initial columbic efficiency of 58% and a high-capacity retention of 81%. Q2 exhibits a stable capacity of 168 mAh·g−1 at a cycling rate of C/3 (124 mA·g−1), which is comparable to other hard carbon anodes reported in the literature. This unique synthesis method opens a pathway for the further tuning of Q-carbon with higher trapping/charging of Na+ ions in improved SIBs.

Hierarchical porous silicon oxycarbide as a stable anode material for lithium-ion batteries

The porous and amorphous silicon oxycarbides (SiOC) derived from polymer precursors are regarded as promising anode materials for lithium-ion batteries due to their high theoretical capacity and minimal volume expansion. Modulations of carbon nanoclusters and reversible species in Si-O-C units have been performed to improve lithium storage properties of SiOC anodes. Herein, we report the effects of pore structure on cycling stability and rate performance of SiOC anode materials, which are prepared by a sol-gel approach using different additions of solvents and a subsequent calcination. The increase in the solvent addition promotes the formation of macropores in the hierarchical porous structure of the SiOC, thereby facilitating rapid Li ion migration and mitigating volume expansion during the lithiation of the SiOC. The as-prepared SiOC anode exhibits competitive reversible capacities of 750.4 mAh g−1 at 0.1 A g−1 after 150 cycles and 437.1 mAh g−1 at 1 A g−1 after 500 cycles, compared to those of previously reported SiOC anodes. This work provides a new strategy for designing of high-capacity and high-stability SiOC anode materials.