ABSTRACT
High-voltage lithium metal batteries (LMBs) have been considered promising next-generation high-energy-density batteries. However, commercial carbonate electrolytes can scarcely be employed in LMBs owing to their poor compatibility with metallic lithium. N,N-dimethylacrylamide (DMAA)-a crosslinkable solubilizer with a high Gutmann donor number-is employed to facilitate the dissolution of insoluble lithium nitrate (LiNO3) in carbonate-based electrolytes and to form gel polymer electrolytes (GPEs) through in situ polymerization. The Li+ solvation structure of the GPEs is regulated using LiNO3 and DMAA, which suppresses the decomposition of LiPF6 and facilitates the formation of an inorganic-rich solid electrolyte interface. Consequently, the Coulombic efficiency (CE) of the Li||Cu cell assembled with a GPE increases to 98.5% at room temperature, and the high-voltage Li||NCM622 cell achieves a capacity retention of 80.1% with a high CE of 99.5% after 400 cycles. The bifunctional polymer electrolytes are anticipated to pave the way for next-generation high-voltage LMBs.
ABSTRACT
Solid-state polymer electrolytes (SPEs) are deemed as a class of sought-after candidates for high-safety and high-energy-density solid-state lithium metal batteries, but their low ionic conductivity, narrow electrochemical windows, and severe interfacial deterioration limit their practical implementations. Herein, an organoboron- and cyano-grafted polymer electrolyte (PVNB) was designed using vinylene carbonate as the polymer backbone and organoboron-modified poly(ethylene glycol) methacrylate and acrylonitrile as the grafted phases, which may facilitate Li-ion transport, immobilize the anions, and enlarge the oxidation voltage window; therefore, the well-tailored PVNB exhibits a high Li-ion transference number (tLi+ = 0.86), a wide electrochemical window (>5 V), and a high ionic conductivity (σ = 9.24 × 10-4 S cm-1) at room temperature (RT). As a result, the electrochemical cyclability and safety of the Li|LiFePO4 and Li|LiNi0.8Co0.1Mn0.1O2 cells with in situ polymerization of PVNB are substantially improved by forming the stable organic-inorganic composite cathode electrolyte interphase (CEI) and the Li3N-LiF-rich solid electrolyte interphase (SEI).
ABSTRACT
BACKGROUND: An ideal preoperative localization method is essential for the resection of small and deep-seated pulmonary nodules by video-assisted thoracoscopic surgery (VATS) in the era of low-dose computed tomography (CT) screening. This study describes a new localization method using electromagnetic navigation bronchoscopy (ENB) and compares it against conventional percutaneous CT-guided methods. METHODS: Between January 2016 and May 2018, 18 consecutive patients with a total of 27 pulmonary nodules underwent ENB localization using patent blue vital dye before thoracoscopy for lung resection at the National Taiwan University Hospital. Over the same period, 268 patients had a total of 325 pulmonary nodules localized by a CT-guided method. Propensity analysis was applied to minimize bias during comparison. RESULTS: Patients were selected using a propensity-score based process, matched for potential risk factors for localization failure, to ensure equal potential prognostic factors in both groups. After matching, the ENB group had 15 patients with a total of 24 pulmonary nodules, and the CT group had 30 patients with 48 pulmonary nodules. No major procedure-related complications occurred in either group. The target pulmonary nodule was not successfully localized for one patient in the ENB group and three in the CT group. The lesions were fully excised after conversion to mini-thoracotomy. Pathological examination confirmed the accuracy of the dye staining. Analysis found a non-significant difference in the success rate of these two localization methods. However, the following parameters were significantly different: interval between localization to surgery, global time, and rate of pneumothorax (p <0.05). CONCLUSIONS: In the era of minimally invasive surgery, surgeons need an efficient one-step way to manage pulmonary nodules. Patent blue vital injection with ENB guidance in the operating room is a new, effective approach to localize small, deep-seated and non-palpable pulmonary lesions, comparable with CT-guided localization.
ABSTRACT
Solid-state polymer electrolytes (SPEs) with high ionic conductivity are desirable for next generation lithium- and sodium-ion batteries with enhanced safety and energy density. Nanoscale fillers such as alumina, silica, and titania nanoparticles are known to improve the ionic conduction of SPEs and the conductivity enhancement is more favorable for nanofillers with a smaller size. However, aggregation of nanoscale fillers in SPEs limits particle size reduction and, in turn, hinders ionic conductivity improvement. Here, a novel poly(ethylene oxide) (PEO)-based nanocomposite polymer electrolyte (NPE) is exploited with carbon quantum dots (CQDs) that are enriched with oxygen-containing functional groups. Well-dispersed, 2.0-3.0 nm diameter CQDs offer numerous Lewis acid sites that effectively increase the dissociation degree of lithium and sodium salts, adsorption of anions, and the amorphicity of the PEO matrix. Thus, the PEO/CQDs-Li electrolyte exhibits an exceptionally high ionic conductivity of 1.39 × 10-4 S cm-1 and a high lithium transference number of 0.48. In addition, the PEO/CQDs-Na electrolyte has ionic conductivity and sodium ion transference number values of 7.17 × 10-5 S cm-1 and 0.42, respectively. It is further showed that all solid-state lithium/sodium rechargeable batteries assembled with PEO/CQDs NPEs display excellent rate performance and cycling stability.
ABSTRACT
40 rainwater samples were collected at Anshun from June 2007 to October 2007 and analysed in terms of pH values, electrical conductivity, major inorganic anions and soluble low molecular weight carboxylic acids. The results showed that pH of individual precipitation events ranged from 3.57-7.09 and the volume weight mean pH value was 4.57. The most abundant carboxylic acids were acetic (volume weight mean concentration 6.75 micromol x L(-1)) and formic (4.61 micromol x L(-1)) followed by oxalic (2.05 micromol x L(-1)). The concentration levels for these three species during summer especially June and July were comparatively high; it implied that organic acids in Anshun may came primarily from emissions from growing vegetations or products of the photochemical reactions of unsaturated hydrocarbons. Carboxylic acids were estimated to account for 32.2% to the free acidity in precipitation. The contribution was higher than in Guiyang rainwater, which indicated contamination by industry in Guiyang was more than in Anshun. The remarkable correlation(p = 0.01) between formic acid and acetic acid suggest that they have similar sources or similar intensity but different sources. And the remarkable correlation (p = 0.01) between and formic acid and oxalic acid showed that the precursors of oxalic acid and formic acid had similar sources. During this period, the overall wet deposition of carboxylic acids were 2.10 mmol/m2. And it appeared mainly in the summer, during which both concentration and contribution to free acidity were also relatively high. Consequently, it was necessary to control emission of organic acids in the summer to reduce frequence of acid rain in Anshun.
