Construction of Low-Impedance and High-Passivated Interphase for Nickel-Rich Cathode by Low-Cost Boron-Containing Electrolyte Additive.

The nickel-rich cathode LiNi0.8 Co0.1 Mn0.1 O2 (NCM811) possesses the advantages of high reversible specific capacity and low cost, thus regarded as a promising cathode material for lithium-ion batteries (LIBs). However, the capacity of the NCM811 decays rapidly at high voltage due to the extremely unstable electrode/electrolyte interphase. The discharge capability at low temperature is also impaired because of the increasing interfacial impedance. Herein, a low-cost film-forming electrolyte additive with multi-function, phenylboronic acid (PBA), was employed to modify the interphasial properties of the NCM811 cathode. Theoretical calculation and experimental results showed that PBA constructed a highly conductive and steady cathode electrolyte interphase (CEI) film through preferential oxidation decomposition, which greatly improved the interfacial properties of the NCM811 cathode at room (25 °C) and low temperature (-10 °C). Specifically, the capacity retention of NCM811/Li cell was increased from 68 % to 87 % after 200 cycles with PBA additive. Moreover, the NCM811/Li cell with PBA additive delivered higher discharge capacity under -10 °C at 0.5 C (173.7 mAh g-1 vs. 111.1 mAh g-1 ). Based on the improvement of NCM811 interphasial properties by additive PBA, the capacity retention of NCM811/graphite full-cell was enhanced from 49 % to 65 % after 200 cycles.

Cost-Efficient Film-Forming Additive for High-Voltage Lithium-Nickel-Manganese Oxide Cathodes.

The operating voltage of lithium-nickel-manganese oxide (LiNi0.5Mn1.5O4, LNMO) cathodes far exceeds the oxidation stability of the commercial electrolytes. The electrolytes undergo oxidation and decomposition during the charge/discharge process, resulting in the capacity fading of a high-voltage LNMO. Therefore, enhancing the interphasial stability of the high-voltage LNMO cathode is critical to promoting its commercial application. Applying a film-forming additive is one of the valid methods to solve the interphasial instability. However, most of the proposed additives are expensive, which increases the cost of the battery. In this work, a new cost-efficient film-forming electrolyte additive, 4-trifluoromethylphenylboronic acid (4TP), is adopted to enhance the long-term cycle stability of LNMO/Li cell at 4.9 V. With only 2 wt % 4TP, the capacity retention of LNMO/Li cell reaches up to 89% from 26% after 480 cycles. Moreover, 4TP is effective in increasing the rate performance of graphite anode. These results show that the 4TP additive can be applied in high-voltage LIBs, which significantly increases the manufacturing cost while improving the battery performance.

Preoperative assessment clinics and case cancellations: a prospective study from a large medical center in China.

BACKGROUND: Preoperative assessment clinics have great benefits in reducing surgical cancellations, saving hospital resources and improving patient satisfaction. However, previous studies did not focus on patients with comorbidities. With advancements in medicine and aging population, the number of elderly patients with multiple comorbidities is increasing. This study was designed to assess the effectiveness of a preoperative assessment clinic for patients with multiple comorbidities. METHODS: This prospective, observational study enrolled patients with multiple comorbidities from Nov 1, 2019 to Oct 31, 2020 in a tertiary teaching hospital in China. Patients either visited the preoperative assessment clinic before admission or received an anesthesia consultation after admission. The impact of clinic visits on operating room cancellations, length of hospital stay before surgery, length of hospital stay after surgery, major postoperative complications, incidence of postoperative intensive care unit (ICU) admission, readmission to any hospital within 30 days after surgeries and total in-hospital costs were analyzed. RESULTS: A total of 326 eligible cases were included. Eighty-seven of 108 cases who visited the clinic before admission were scheduled for selective surgeries. In all, 218 patients received an anesthesia consultation after admission. The cancellation rate in the inpatient group was 7.80%, while no surgeries were cancelled in preclinic group (P=0.016). A preoperative assessment clinic visit statistically decreased the length of in-hospital stays before surgery from 93.02 to 76.11 h (P=0.010). After propensity score matching, significant differences in operating room cancellations (0 vs. 6.48%; P=0.015) and length of stay before surgery (76.11 vs. 92.22 h; P=0.038) persisted between two groups. No significant differences between the two groups were found in terms of prognosis, including major postoperative complications, incidence of postoperative ICU admissions, and readmissions to any hospital within 30 days (P>0.05). CONCLUSIONS: Among patients with comorbidities undergoing major surgeries, a preoperative assessment clinic visit was more efficient than an anesthesia consultation after admission. These findings may provide impetus for the opening of preoperative assessment clinics for critical patients in China.

Nano-Fe3C@PGC as a novel low-cost anode electrocatalyst for superior performance microbial fuel cells.

We report a novel anode electrocatalyst, iron carbide nanoparticles dispersed in porous graphitized carbon (Nano-Fe3C@PGC), which is synthesized by facile approach involving a direct pyrolysis of ferrous gluconate and a following removal of free iron, but provides microbial fuel cells with superior performances. The physical characterizations confirm the unique configuration of iron carbide nanoparticles with porous graphitized carbon. Electrochemical measurements demonstrate that the as-synthesized Nano-Fe3C@PGC exhibits an outstanding electrocatalytic activity toward the charge transfer between bacteria and anode. Equipped with Nano-Fe3C@PGC, the microbial fuel cells based on a mixed bacterium culture yields a power density of 1856 mW m-2. The resulting excellent performance is attributed to the large electrochemical active area and the high electronic conductivity that porous graphitized carbon provides and the enriched electrochemically active microorganisms and enhanced activity towards the redox reactions in microorganisms by Fe3C nanoparticles.