Search

LiFePO4 is a type of cathode material with good safety and long service life. However, the problems of the low Li ion diffusion rate and low electron conductivity limit the application of LiFePO4 in the field of electric vehicles. In this paper, FePO4 with different grain sizes was prepared via the air oxidation precipitation method and then sintered to prepare LiFePO4. The refined grain can shorten the diffusion distance of Li+, accelerate the diffusion of Li+, and improve the diffusion coefficient of Li+. The results show that LiFePO4 with a smaller grain size has better electrochemical performance. The discharge capacity of the first cycle is 151.3 mAh g−1 at 1 C, and the capacity retention rate is 95.04% after 230 cycles. Its rate performance is more outstanding, not only at 0.2 C, where the discharge capacity is as high as 155 mAh g−1, but also at 10 C, the capacity fade is less, and it can still reach 131 mAh g−1. The air oxidation precipitation method reduces the production cost, shortens the production process, and prepares FePO4 with small grains, which provides a reference for further improving the properties of precursors and LiFePO4.

BACKGROUND: We aimed to evaluate the immediate and mid-term outcomes of transthoracic minimally invasive closure (TMIC) of ruptured sinus of Valsalva aneurysm (RSVA), which is a rare and mostly congenital heart disease. METHODS: From January 2014 to November 2020, 19 patients (16 males, 3 females) with RSVA were selected for TMIC and were followed up at our centre. Data were analysed from our prospectively collected database and clinical mid-term follow-up was obtained. RESULTS: Among these 19 cases, transthoracic echocardiography showed rupture of the right coronary sinus to the right atrium in 9 patients, non-coronary sinus rupture to the right atrium in 7 patients, and right coronary sinus rupture to the right ventricle in 3 patients. Most (13/19) cases were New York Heart Association (NYHA) functional class III or IV. The mean diameters of the defect from the aortic end and ruptured site were 8.8±3.0 and 6.4±2.6 mm, respectively. TMIC was attempted using ventricular septal defect (VSD)/patent ductus arteriosus (PDA) occluders 2–7 mm larger than the aortic ends of the defects. All patients were successfully treated by TMIC and achieved complete closure at discharge after a mean hospital stay length of 6.2±2.5 days. Seventeen patients were NYHA class I while 2 patients were NYHA class II. No cases of residual shunts, device embolization, infective endocarditis, or aortic regurgitation were observed during a median follow-up of 36 months (range, 16–84 months). CONCLUSIONS: In appropriately selected cases with RSVA, TMIC is an attractive alternative to surgery, with a high technical success rate and encouraging short-term and mid-term outcomes. However, long-term follow-up is needed.

Sodium-ion batteries (SIBs) with huge cost advantages will show extraordinary talents in low-speed electric vehicles, energy storage, and base station communications. Manganese oxides are promising candidates for cathode materials, rapid capacity decay, and poor electrochemical performance that limit its commercial applications. Here, the nanosheets with exposed active crystal planes are prepared through a simple NH3∙H2O-assisted sol-gel process and subsequent high-temperature calcination. The unique structure considerably reduces the Na+ diffusion path for the excellent Na+ diffusion kinetics. The final results confirm that the NMO-pH6 sample, exposed to the active planes, has high energy density (557.9 Wh kg−1 at 0.1 C) and outstanding electrochemical performance, especially the rate performance (93.8 mAh g−1 at 5 C and 79.95 %, 100 cycles at 1 C). More importantly, it will facilitate the further construction of advanced cathode materials for high-performance SIBs.

Li-rich oxides are considered as the most commercial potential cathode materials due to the high theoretical specific discharge capacity. Here, ZrO2 in different crystalline states are applied as the coating layers to enhance the electrochemical performance of hollow Li[Li0.2Mn0.54Ni0.13Co0.13]O2 materials. Meanwhile, a series of characterizations (XRD, SEM, TEM, EDX etc.) are conducted to compare the effects of ZrO2 coating layer with different crystalline states on the host material. The results elucidate that the Li-rich Mn-based material with the polycrystal ZrO2 coating layer has a slight advantage in rate performance, while the host material with the single crystal ZrO2-coating layer has a better cycling performance and effectively suppresses voltage decay with the effect of excellently inhibiting layered to spinel-like phase transition and metal dissolution during charging and discharging process.

The pure Shupe effect is substantially reduced in a fiber optic gyroscope (FOG) with symmetrical windings. However, the effect of the temperature-induced nonuniformity of the stress in the coil depends on the mean temperature derivative (T-dot). Research on precision winding technology has discovered that the symmetry of optical fiber rings affects the temperature performance of fiber optic gyroscopes. Optical fiber rings with good symmetry also have good temperature performance. This paper first establishes a temperature drift model of optical fiber rings that includes the Shupe effect and T-dot effect and then uses finite element simulation to analyze the drift error of optical fiber rings in a variable temperature environment. Analysis shows that this drift is caused by the variation and uneven distribution of the fiber length and the refractive index in the positive and negative winding of the optical fiber ring, which results in a residual phase difference that is directly related to the symmetry of the optical fiber ring. Simulation and analysis show that balancing the residual phase difference of the optical fiber ring can be achieved by cutting the length of the optical fiber ring at both ends. This paper uses optical frequency domain reflectometry (OFDR) technology to precisely test the symmetry of the optical fiber ring, ensuring accurate adjustment of the lengths at both ends of the optical fiber ring. Experimental tests on two gyroscopes have shown that the optical fiber ring with a smaller drift error can be obtained after testing and adjusting its length. The experimental data indicates that the bias stability of two laboratory gyros are increased by 23.6% and 18.1%, and the bias range are reduced by 22.4% and 30.0%.

Li-rich cathode materials have higher discharge capacity and lower cost than conventional electrode materials such as LiCoO2. However, they suffer from rapid capacity fading caused by irreversible phase transition and interfacial instability during the electrochemical cycling. La–Co–O (denoted as LC) compound possess good electronic conductivity and superior thermal stability, which could be used as a promising coating layer to suppress Mn dissolution as well as to facilitate electrical transfer. Furthermore, La–Co–O (LC) coating layer could decrease the Mn3+ ions on the surface of Li1.2Mn0.54Ni0.13Co0.13O2 (denoted as LMNC), thus stabilize the surface structure. Herein, we present La–Co–O (LC) coating layer on the surface of LMNC via an artful sol-gel-based method with a thickness below 50 nm. XPS, EDS and TEM tests were applied to confirm the existence of LC coating layer. 2 mol% LC coated LMNC sample shows much improved cycle stability at 1C (206.3 mAh g−1, 86.2% capacity retention after 100 cycles) and good rate capability especially at high rates. In addition, LC coating could effectively suppress voltage fading of LMNC. EIS results reveal that the LC modified LMNC materials exhibit better electrochemical kinetics than the pristine one.

Electrode-electrolyte interface side reactions cause the fast capacity fading of Ni-rich cathode, especially at high cutoff voltages and high temperatures. This is the main obstacle for their commercial application. Herein, a hybrid ZrO2-Li2ZrO3 (LZO) coating layer was fabricated through a wet process on LiNi0.7Co0.15Mn0.15O2 (NCM) cathode materials. The structure and chemical composition of the ZrO2-Li2ZrO3 coating layer were studied by the characterizations of XRD, SEM, TEM, and XPS. The ZrO2-Li2ZrO3-coated LiNi0.7Co0.15Mn0.15O2 cathode improved cycling stabilities at both 25 and 55 °C in the case of high cutoff voltage. In detail, ZrO2-Li2ZrO3-coated NCM (LZO-NCM) delivers a 187.40 mAh g−1 with 83.4% capacity retention after 100 cycles at 1C over 3.0–4.5 V, and it is far higher than that of uncoated sample (71.4%). At elevated temperature (55 °C), the ZrO2-Li2ZrO3-coated sample also maintains 79% capacity retention after 100 cycles (3.0–4.5 V, 1C), which is higher than the 61.5% capacity retention of the pristine electrode. The hybrid ZrO2-Li2ZrO3 coating could not only keep the bulk structure stability but also prevent the electrochemical resistance which varies after cycles. Thereby, the electrochemical properties were improved significantly.

A novel architecture, one-dimensional, microrod-like Ni-rich LiNi0.8Co0.1Mn0.1O2 cathodes assembled from small primary particles have been successfully constructed through morphology-conserved and ...

Ni-rich cathode material is taking more and more important position in energy storage and conversion because of their high capacity. But the gap between the demanded and actual capacity still hinder the development of electric vehicle industry. Herein, the Ni-rich (Ni content > 85%) cathode material has received extensive concern. In our research, LiNi0.88Co0.09Al0.03O2 was prepared with solvothermal method by two steps. Meanwhile, the different solvents in solvothermal route are investigated. It is found that LiNi0.88Co0.09Al0.03O2 prepared by isopropyl alcohol shows an excellent capacity retention which is up to 82.3% after 100 cycles at 55 °C, much higher than that prepared by ethyl alcohol (64.0%). The enhanced performance could be ascribed to the specific morphology formed in solvothermal period by the proper solvent.

Silicon dioxide (SiO2) has great potential application as anode materials for lithium-ion battery owing to the rich resource, economic cost, and easy preparation. SiO2/Ti3C2 (ST-1, ST-2, and ST-3, respectively) nano-/microcomposites were synthesized via three different methods (sol-gel, centrifugal-drying, and freeze-drying method), and the SEM results indicate that abundant SiO2 particles are distributed on the modified surface of multilayer Ti3C2 nanosheets, forming stable multiphase structures. Electrochemical results demonstrate that the SiO2/Ti3C2 composites can deliver good electrochemical performance and almost have no capacities decay after hundreds of cycles. In particular, the structure properties of ST-3 composite synthesized by freeze-drying were well preserved, delivering a reversible discharge capacity of 242.4 mAh g−1 at 100 mA g−1, even after high-rate test (5000 mA g−1), still exerting 258.6 mAh g−1 reversible discharge capacity at 100 mA g−1, indicating good structural stability and electrochemical reversibility of ST-3 composite for lithium-ion batteries.

In this research, the Pr-doped LiNi0.8Co0.1Mn0.1O2 material was prepared successfully via the solid-state method. The significant improvement on the material structural stability was confirmed by the experimental results (XRD, SEM, and XPS, etc.). What’s more, the Pr-2500 sample exhibited the best electrochemical performance with the capacity retention rate 94.43% (3.0–4.4 V, 1 C (180 mA g−1), 25 °C, after 100 cycles), while the capacity retention rate of the Pristine was only 83.40%. Furthermore, the degree of the electrochemical polarization and the electrochemical impedance were reduced after modification. The excellent electrochemical properties were ascribed to the higher structure stability after modification, and the more stable structure may benefit from the higher bond dissociation energies (753 kJ mol−1) of Pr-O.

High-capacity germanium-based anode materials are alternative materials for outstanding electrochemical performance lithium-ion batteries (LIBs), but severe volume variation and pulverization problems during charging-discharging processes can seriously affect their electrochemical performance. In addressing this challenge, a simple strategy was used to prepare the self-assembled GeOX/Ti3C2TX composite in which the GeOX nanoparticles can grow directly on Ti3C2TX layers. Nanoscale GeOX uniformly renucleates on the surface and interlayers of Ti3C2TX, forming the stable multiphase structure, which guarantees its excellent electrochemical performance. Electrochemical evaluation has shown that the rate capability and reversibility of GeOX/Ti3C2TX are both greatly improved, which delivers a reversible discharge specific capacity of above 1400 mAh g-1 (at 100 mA g-1) and a reversible specific capacity of 900 mAh g-1 after 50 cycles while it still maintains a stable specific capacity of 725 mAh g-1 at 5000 mA g-1. Furthermore, the composite exhibits an exceptionally superior rate capability, making it a good electrochemical performance anode for LIBs.

In this paper, the dual-modified LiNi0.8Co0.1Mn0.1O2 via Gd2O3 is successfully obtained by the solid-state method. The phenomenon of Li/Ni cation mixing and structural stability of materials has been improved after Gd2O3 modification. Additionally, the lower average discharge voltage drop (ΔEd) and electrochemical polarization of the batteries are obtained after modification. Simultaneously, the dual-modified material via Gd2O3 exhibits the high capacity retention of 94.50% compared with that (83.40%) of the Pristine (3.0–4.4 V, 1 C (180 mA g−1), 25 °C, after 100 cycles). The excellent electrochemical properties ascribe to the higher bond dissociation energies of Gd-O (716 kJ mol−1) and the stable coating layer of Gd2O3.

As we know, noble metal (Pt, Pd and Au) with appropriate adsorption free energy of H atoms and higher work function as cocatalyst has been considered to be an effective tactic to enhance photocatalytic activity. However, they are limited severely by scarcity and high-cost. Herein, Zn0.5Cd0.5S solid-solution photocatalyst decorated with noble metal-free NiCo cocatalyst has been successfully obtained through one-step photochemical route. It is found that the lifespan of charge carriers of Zn0.5Cd0.5S@NiCo can be prolonged dramatically after modification, and the photocatalytic H2 rate reach to 34.7 mmol g−1·h−1 is nearly 9 times higher than the bare Zn0.5Cd0.5S (λ ≥ 420 nm). The superior photocatalytic activity for ZCS@NiCo could be mainly ascribed to higher separation and transfer efficiency of photogenerated carriers by introduced bimetallic NiCo cocatalysts possessing the superior electron transfer property and reducing the onset over-potential of water reduction, which was proved by experiment. This study can provide a potential strategy to design a more efficient noble metal-free cocatalyst over photocatalyst.

Generally, the synthesis of precursors for metal oxide anode and LiNiO2-based cathode materials undergoes different routes. Herein, NiO anode and LiNiO2 cathode material for lithium-ion batteries are synthesized by sharing the rod-like NiC2O4 precursor which is prepared by the solvothermal method. As a result, NiO and LiNiO2 exhibit special fibrous structure and promising electrchemical performances without any modification. Especially, the synthesis of fibrous LiNiO2 via a solvothermal route and its electrochemical properties are first reported. The excellent electrochemical performances of LiNiO2 can be attributed to the decent fiber architecture which enhances wettability by the electrolyte and shortens Li+ diffusion pathways.

New materials with different morphologies, nanostructures, and components can have structural advantages for application in materials science. Multicomponent-active hybrid nanostructured materials are among the best candidates for application in electrode materials. Spray pyrolysis and solvothermal synthesis are two popular methods for the preparation of multicomponent-active hybrid nanostructured materials. In this study, the two types of NiO-MnCo2 O4 -Ni6 MnO8 hybrid anode materials for use in lithium-ion batteries were synthesized by two different methods (spray pyrolysis and solvothermal synthesis), and the differences in their physical and electrochemical properties were compared. The two types of anode material exhibited the same hierarchical hybrid composition, but some different physical characteristics, which affected their electrochemical performance.

The Eh-pH diagrams for Ni-Co-Mn-CO3-H2O system at various temperatures and ion concentrations are simulated via OLI studio based on the fundamentals of thermodynamic equilibrium. A co-existence area for NiCO3, CoCO3, and MnCO3 is observed visually from the Eh-pH diagrams, which thermodynamically proves the stability of these species in aqueous solutions, and the possibility of co-precipitating polymetallic carbonate. The simulation results also demonstrate that a higher temperature and/or a more dilute solution are not in favor of the co-precipitation. With the predicted pH ranges from the Eh-pH diagrams, a confirmative experiment was conducted to synthesize Ni0.13Co0.13Mn0.54(CO3)0.8, the precursor for preparing Li1.2Ni0.13Co0.13Mn0.54O2, which is a promising cathode material for next-generation LIBs. The physical properties of both materials are characterized in detail, and the electrochemical performance for the final cathode material was tested. The results show that Ni2+, Co2+, and Mn2+ ions in solution are homogeneously co-precipitated in the form of polymetallic carbonate. The Li1.2Ni0.13Co0.13Mn0.54O2 material obtained from the carbonate precursor has a typical structure of Li- and Mn-rich cathodes and yields an initial discharge capacity of 296.0 mAh g−1 at 0.1 C and 188.1 mAh g−1 after 100 cycles at 1 C rate. It was verified that the OLI-assisted Eh-pH simulation is consistent with the experimental measurements.

Transition-metal sulfides have been considered as promising anode materials for lithium-ion batteries (LIBs) due to their high theoretical specific capacity and superior electrochemical performance. However, the large volume change during the discharge/charge process causes structural pulverization, resulting in rapid capacity decline and the loss of active materials. Herein, we report Co

Nickel–Cobalt–Aluminum (NCA) cathode materials for lithium-ion batteries (LIBs) are conventionally synthesized by chemical co-precipitation. However, the co-precipitation of Ni2+, Co2+, and Al3+ is difficult to control because the three ions have different solubility product constants. This study proposes a new synthetic route of NCA, which allows fabrication of fine and well-constructed NCA cathode materials by a high temperature solid-state reaction assisted by a fast solvothermal process. The capacity of the LiNi0.88Co0.09Al0.03O2 as-synthesized by the solvothermal method was 154.6 mA h g−1 at 55 °C after 100 cycles, corresponding to 75.93% retention. In comparison, NCA prepared by the co-precipitation method delivered only 130.3 mA h g−1 after 100 cycles, with a retention of 63.31%. Therefore, the fast solvothermal process-assisted high temperature solid-state method is a promising candidate for synthesizing high-performance NCA cathode materials.

The interfacial instability and intrinsic structural degradation of cathodes, which cause performance loss and even a safety hazard, are a critical challenge in Ni-rich cathodes during long-term cycling. Herein, potassium phosphate monobasic modified LiNi0.8Co0.1Mn0.1O2, whereby a Li3PO4 coating layer coupled with trace-levels of co-doped K+ and PO43− are synchronously constructed, was successfully synthesized via a one-step calcination process at high temperature. Impressively, the optimized 2@KP-NCM delivered superior electrochemical performance, particularly at high rate and elevated temperature. High capacity retention rates of 90.6% at a 5C-rate at room temperature after 200 cycles and 92% at a 1C-rate at 55 °C after 100 cycles in the voltage range of 3.0–4.4 V were reached, and these are clearly higher than those of the pristine cathode (only 73.4% and 51%, respectively). Such a great improvement on the cycling stability is mainly attributed to the pillaring effect of doped-ions on stabilizing the layered structure and suppressing the deleterious irreversible phase-transition as well as the interfacial protective layer effectively protecting the active core cathode from the chemical attack of side products.

SiO/C is believed to be one of the most promising anode material for lithium-ion batteries due to the low operation potential and superior theoretical capacity. However, the substantial volume change during cycling process limits its further practical application. Herein, we report an affordable and highly effective approach to enhancing the electrochemical performance by adding a small amount of single-walled carbon nanotubes (SWCNT) as conductive additive for SiO/C anodes. An efficient liquid-phase mixing approach is employed to evenly disperse the SWCNT into silicon oxide/graphite composite anode for lithium-ion batteries (LIBs). The electrochemical capability is carried out using pouch full cells with commercial electrode areal loading and mass loading. The addition of SWCNT (0.5%) reduces film resistance and direct current resistance (DCR) for charging. The lithium-ion diffusion coefficient is 6.32 × 10−15 cm2 s−1 for SWCNT-added sample, which is an order of magnitude higher than that of the sample without SWCNT (2.33 × 10−16 cm2 s−1). Furthermore, the battery assembled by the SWCNT-adding electrode shows better rate performance and cycle stability. The charge efficiency improves 1.25 times at 4 C charging, which enables fast charging for LIBs. The cycling results show that SWCNT-adding electrode displays capacity retention of 90.30% after 600 cycles at 1 C. Furthermore, the loading of SiO/C electrode increases from 93.4 to 95.4 wt%, which is beneficial for improvement of energy density. It is worth noting that it suggests a well-designed recipe for the practical application of SWCNT for LIBs.

LiNi0.5Mn1.5O4 (LNMO) is a promising cathode material for lithium-ion batteries due to its high discharge voltage, low cost, environmental friendliness, and high energy density. To enhance the electrochemical performance of LNMO, Cd is innovatively employed as a modifying agent. Structural and morphological characterizations confirm that CdO is successfully wrapped on the surface of LNMO. Further physical, chemical, and electrochemical detections verify the phase transition of LNMO. The CdO-coated samples show excellent cyclability and rate performance. The CdO-coated LNMO (Cd 0.4 wt.%) exhibits a discharge capacity of 133.3 mAh g−1 with a retention rate of 95.2% after 300 cycles at 1-C rate (3.5–4.8 V), while that of the pristine is only 89.4%. Even at 10-C rates, the CdO-coated LNMO has an initial discharge capacity of 120.0 mAh g−1 with a retention rate of 92.3% after 300 cycles at the same voltage limit. Specifically, at the first of cycling, the newly formed Cd-F compounds and CdO layer could suppress the side reactions and reduce the formation of surface film. Finally, the process of kinetics is improved.

The structural collapse and surface chemical degradation of nickel-rich layered oxide cathodes (NCM) of lithium-ion batteries during operation, which result in severe capacity attenuation, are the major challenges that hinder their commercial development. To improve the cycle and rate performances of LiNi0.8Co0.1Mn0.1O2 (NCM811), in this study, we have constructed a double-shell structure protective layer with a surface CeO2-x coating and interfacial spinel-like phase, which mitigate particle microcrack formation and isolate the NCM811 particles from electrolyte erosion. Additionally, during heat-treatment calcination, tetravalent cerium ions with strong oxidation ability can be partially doped into the material, which causes partial oxidation of Ni2+ to Ni3+, thereby reducing the Li+/Ni2+ mixing. The strong Ce-O bonds formed in the lattice help to improve the stability of the structure in the highly de-lithiated state. Thus, the synergy of multifunctional cerium modification effectively improves the structural stability and electrochemical kinetics of the material during cycling. Impressively, the obtained Ce-NCM811 exhibits capacity retention of 80.3% at a high discharge rate of 8 C after 500 cycles, which is much higher than that of the pristine cathode (only 44.3%). This work successfully designed a material with multi-functional Ce modification to provide a basis for Ni-rich cathode materials, which is crucial as it effectively improves the electrochemical performance.