All‐solid‐state lithium batteries offer notable advantages over conventional Li–ion batteries with liquid electrolytes in terms of energy density, stability, and safety. To realize this technology, ...it is critical to develop highly reliable solid‐state inorganic electrolytes with high ionic conductivities and adequate processability. Li1+xAlxTi2−x(PO4)3 (LATP) with a NASICON (Na superionic conductor)‐like structure is regarded as a potential solid electrolyte, owing to its high “bulk” conductivity (ca. 10−3 S cm−1) and excellent stability against air and moisture. However, the solid LATP electrolyte still suffers from a low “total” conductivity, mainly owing to the blocking effect of grain boundaries to Li+ conduction. In this study, an LATP–Bi2O3 composite solid electrolyte shows very high total conductivity (9.4×10−4 S cm−1) at room temperature. Bi2O3 acts as a microstructural modifier to effectively reduce the fabrication temperature of the electrolyte and to enhance its ionic conductivity. Bi2O3 promotes the densification of the LATP electrolyte, thereby improving its structural integrity, and at the same time, it facilitates Li+ conduction, leading to reduced grain‐boundary resistance. The feasibility of the LATP–Bi2O3 composite electrolyte in all‐solid‐state Li batteries is also examined in this study.
Superionic conductivity: LATP–Bi2O3 composite solid electrolyte (LATP=Li1+xAlxTi2−x(PO4)3) shows very high total conductivity (9.4×10−4 S cm−1) at room temperature. The Bi2O3 acts as a microstructural modifier to effectively reduce the fabrication temperature and promote the densification of the LATP electrolyte, thereby improving its structural integrity and ionic conductivity.
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•Defect in graphene-silicon(d-Gr/Si) composites enhances electrochemical performance.•Li adsorption energies in the d-Gr/Si were less than -0.6 eV and 0.25 eV at pristine ...Gr/Si.•Defected Gr/Si is more thermionically stable than pristine Gr/Si.•Charge transfer on defects improves electrical conduction and mechanical strength at interfaces.•Our analyses elucidate that defect engineering enhances Li capacity and mechanical strength.
Carbon-coated silicon materials are considered as promising anode materials in high-capacity lithium-ion batteries (LIBs). Theoretically, using graphene as the anode material in the LIB would afford high electrical conductivity, mechanical stability of Si, and suppression of the unstable solid–electrolyte interface. However, its usage is hindered by its electrochemical characteristic, which is not electrochemically active when combined with lithium. Therefore, research on graphene as the anode and coated material in LIBs has been conducted using defect engineering to enhance the storage capacity of graphene. Although the electrochemical characteristics of various defects in graphene have been studied experimentally and theoretically, graphene-based composite anode materials such as graphene–silicon composite electrodes have rarely been studied from the electrochemical and mechanical perspectives. In this study, lithium adsorptions are conducted on various defected graphene and graphene–silicon composites using density functional theory calculation. The formation energies of Li on the various defected graphene are assessed, and the mechanical strengths of the graphene–silicon composites are analyzed. Our calculations validate that the defects in graphene enhance the electrochemical adsorptions and interfacial mechanical strengths of the graphene and graphene–silicon composites. During lithiation, the defects mediate greater interfacial adhesion of the silicon–graphene composite. Hence, we elucidate that defected graphene increases the electro-chemo mechanical stabilities of silicon composites in high-capacity LIBs.
Abstract
The realisation of fast-charging lithium-ion batteries with long cycle lifetimes is hindered by the uncontrollable plating of metallic Li on the graphite anode during high-rate charging. ...Here we report that surface engineering of graphite with a cooperative biphasic MoO
x
–MoP
x
promoter improves the charging rate and suppresses Li plating without compromising energy density. We design and synthesise MoO
x
–MoP
x
/graphite via controllable and scalable surface engineering, i.e., the deposition of a MoO
x
nanolayer on the graphite surface, followed by vapour-induced partial phase transformation of MoO
x
to MoP
x
. A variety of analytical studies combined with thermodynamic calculations demonstrate that MoO
x
effectively mitigates the formation of resistive films on the graphite surface, while MoP
x
hosts Li
+
at relatively high potentials via a fast intercalation reaction and plays a dominant role in lowering the Li
+
adsorption energy. The MoO
x
–MoP
x
/graphite anode exhibits a fast-charging capability (<10 min charging for 80% of the capacity) and stable cycling performance without any signs of Li plating over 300 cycles when coupled with a LiNi
0.6
Co
0.2
Mn
0.2
O
2
cathode. Thus, the developed approach paves the way to the design of advanced anode materials for fast-charging Li-ion batteries.
A newly prepared type of carbon felt with oxygen‐rich phosphate groups is proposed as a promising electrode with good stability for all‐vanadium redox flow batteries (VRFBs). Through direct surface ...modification with ammonium hexafluorophosphate (NH4PF6), phosphorus can be successfully incorporated onto the surface of the carbon felt by forming phosphate functional groups with −OH chemical moieties that exhibit good hydrophilicity. The electrochemical reactivity of the carbon felt toward the redox reactions of VO2+/VO2+ (in the catholyte) and V3+/V2+ (in the anolyte) can be effectively improved owing to the superior catalytic effects of the oxygen‐rich phosphate groups. Furthermore, undesirable hydrogen evolution can be suppressed by minimizing the overpotential for the V3+/V2+ redox reaction in the anolyte of the VRFB. Cell‐cycling tests with the catalyzed electrodes show improved energy efficiencies of 88.2 and 87.2 % in the 1st and 20th cycles compared with 83.0 and 81.1 %, respectively, for the pristine electrodes at a constant current density of 32 mA cm−2. These improvements are mainly attributed to the faster charge transfer allowed by the integration of the oxygen‐rich phosphate groups on the carbon‐felt electrode.
C what P can do: Herein, we introduce a simple and low‐costing surface modification method to incorporate oxygen‐rich phosphate groups directly onto the surface of carbon felt, which is a well‐known, commercialized 3 D structured carbon electrode. This simple method exhibits high performance and can be easily adapted to other redox flow battery systems with carbon felts.
A potential solid electrolyte for realizing all‐solid‐state battery (ASB) technology has been discovered in the form of Li10GeP2S12 (LGPS), a lithium superionic conductor with a high ionic ...conductivity (≈12 mS cm−1). Unfortunately, the achievable Li+ conductivity of LGPS is limited in a sheet‐type composite electrode owing to the porosity of this electrode structure. For the practical implementation of LGPS, it is crucial to control the pore structures of the composite electrode, as well as the interfaces between the active materials and solid‐ electrolyte particles. Herein, the addition of an ionic liquid, N‐methyl‐N‐butylpyrrolidinium bis(trifluoromethylsulfonyl)imide (Py14TFSI), is proposed as a pore filler for constructing a highly reliable electrode structure using LGPS. Py14TFSI is coated onto the surface of LGPS powder through a wet process and a sheet‐type composite electrode is prepared using a conventional casting procedure. The Py14TFSI‐embedded composite electrode exhibits significantly improved reversible capacity and power characteristics. It is suggested that pore‐filling with Py14TFSI is effective for increasing contact areas and building robust interfaces between the active materials and solid‐electrolyte particles, leading to the generation of additional Li+ pathways in the composite electrode of ASBs.
A solid performance: Ionic liquid is proposed as a pore filler in a composite electrode for constructing a high‐performance all‐solid‐state battery. The pore‐filling improves the contact area between the cathode materials and solid electrolyte particles and minimizes overpotential at the interfaces. In practice, the proposed all‐solid‐state battery exhibits comparable electrochemical performance to conventional lithium‐ion batteries at room temperature.
•Bi-DPC derived from MOF is synthesized via chemical etching and galvanic displacement.•Bi-DPC effectively reduces the overpotential associated with the Li metallization reaction.•Bi facilitates a ...reversible and uniform Li plating/stripping by forming an alloy with Li.•Bi serves as a superior alternative to Ag, outperforming in terms of both cost-effectiveness and efficiency.
Utilizing carbon materials as 3D lithium (Li) hosts hold a significant interest in constructing high-energy batteries. However, there are ongoing challenges associated with these frameworks owing to their poor Li affinity. Recent advancements, including alloying reactions with precious metals like silver (Ag) and gold (Au), have emerged as a promising technique to enhance the electrochemical performance of these host materials. Nevertheless, the search for cost-effective alternatives remains a pressing demand. Herein, this work employed galvanic displacement (GD) to integrate bismuth into disordered porous carbon (Bi-DPC) and optimized across different concentrations (0.01, 0.05, 0.1 M). As a result, the Li deposition onto the Bi-DPC surface exhibited dendrite-free planar morphologies, revealing an outstanding electrochemical performance, including a high CE of around 100 % over more than 100 cycles. These findings underscore the potential of Bi-infused porous carbon as a promising alternative for enhancing Li deposition processes.
Non‐stoichiometric SiOx based materials have gained much attention as high capacity lithium storage materials. However, their anode performance of these materials should be further improved for their ...commercial success. A conductive polymer, poly(3,4‐ethylenedioxythiophene):poly(4‐styrenesulfonate) (PEDOT:PSS), is employed as a flexible electrical interconnector to improve the electrochemical performance of Si/SiOx nanosphere anode materials for lithium ion batteries (LIBs). The resulting Si/SiOx‐PEDOT:PSS core–shell structured material with the small amount (1 wt %) of PEDOT:PSS shows the improved initial reversible capacity of 968.2 mA h g−1 with excellent long‐term cycle performance over 200 cycles. These promising properties can be attributed to the use of the electroconductive and flexible PEDOT:PSS shell layer, which protects the electrical conduction pathways in the electrode from the large volume changes of silicon during cycling.
Si shells: The conductive polymer poly(3,4‐ethylenedioxythiophene):poly(4‐styrenesulfonate) (PEDOT:PSS) is used to prepare core–shell‐structured Si/SiOx‐PEDOT:PSS nanospheres for lithium‐ion batteries. The nanospheres show improved electrochemical performance by preserving conducting paths in the silicon‐based anode materials despite volume changes during cycling.
Background
The transoral endoscopic thyroidectomy vestibular approach (TOETVA) has been the subject of increasing interest from several institutions around the world over the last 2 years. Recently, ...we successfully performed TOETVA in live human patients without CO
2
gas using our newly designed retractable blade.
Methods
We reviewed the medical records of 15 consecutive patients who underwent gasless TOETVA using a self-retaining retractor.
Results
We successfully performed 13 thyroid lobectomies and 2 total thyroidectomies in 15 patients. No patient exhibited serious postoperative complications such as recurrent laryngeal nerve palsy and permanent hypocalcemia. One patient developed transient hypocalcemia but recovered within 2 months. No patient developed a wound infection; furthermore, no visible scar or dimpling was evident on the neck of any patient.
Conclusion
Gasless TOETVA provides enough working space and good visibility to perform thyroid surgery without any risk of CO
2
gas-related complications.
Background
Transoral endoscopic thyroidectomy vestibular approach is expected to be a safe alternative to open surgery for certain patients and has been used increasingly by several surgeons around ...the world for the past 2 years. The purpose of this paper is to review our 2-year experience and describe in detail our preoperative considerations, patient selection, operating room settings, anesthetic considerations, surgical technique, postoperative management, and outcomes.
Methods
We reviewed the medical records of 65 consecutive patients who underwent transoral endoscopic thyroidectomy between July 2016 and May 2018 in our hospital.
Results
We have performed 65 thyroid surgeries (54 thyroid lobectomies, 1 completion thyroidectomy, and 10 total thyroidectomies) in 64 patients. Postoperative pathology revealed papillary carcinoma in 55 patients (84.6%), follicular carcinoma in two (3.1%), hyalinizing trabecular tumor in one (1.5%), and other benign tumor in seven (10.8%). All surgical margins were negative. Two (3.1%) patients developed transient vocal cord palsy but recovered within 2 months. One (1.5%) patient with vocal cord palsy had not recovered by 3 months after surgery. Five (7.7%) patients who underwent total thyroidectomy developed transient hypocalcemia but recovered within 2 months.
Conclusion
Although transoral thyroid surgery is a relatively recent technique requiring further validation, it affords several advantages. Transoral thyroid surgery has not yet been universally accepted, but may be the best choice for thyroid surgery in the future.
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