Localized concentration reversal of lithium during intercalation into nanoparticles.

Nanoparticulate electrodes, such as Li x FePO4, have unique advantages over their microparticulate counterparts for the applications in Li-ion batteries because of the shortened diffusion path and access to nonequilibrium routes for fast Li incorporation, thus radically boosting power density of the electrodes. However, how Li intercalation occurs locally in a single nanoparticle of such materials remains unresolved because real-time observation at such a fine scale is still lacking. We report visualization of local Li intercalation via solid-solution transformation in individual Li x FePO4 nanoparticles, enabled by probing sub-angstrom changes in the lattice spacing in situ. The real-time observation reveals inhomogeneous intercalation, accompanied with an unexpected reversal of Li concentration at the nanometer scale. The origin of the reversal phenomenon is elucidated through phase-field simulations, and it is attributed to the presence of structurally different regions that have distinct chemical potential functions. The findings from this study provide a new perspective on the local intercalation dynamics in battery electrodes

Effect of tea polyphenols on intestinal barrier and immune function in weaned lambs

IntroductionThe purpose of this study was to explore the effects of tea polyphenols on growth performance, cytokine content, intestinal antioxidant status and intestinal barrier function of lambs, in order to provide reference for intestinal health of ruminants.MethodsThirty weaned lambs (average initial weight 9.32 ± 1.72 kg) were randomly divided into five groups with six lambs in each group. The control group did not add anything but the basic diet mainly composed of Pennisetum and Corn, and the other four groups added 2, 4, 6 g/kg tea polyphenols and 50 mg/kg chlortetracycline to the basic diet, respectively. The experiment lasted for 42 days.ResultsDietary tea polyphenols improved the growth and stress response and reduced intestinal permeability of lambs (p > 0.05), while CTC did not affect the final lamb weight (p > 0.05). Both tea phenols and CTC significantly reduced inflammatory factors and enhanced the immune system (p > 0.05). Dietary tea polyphenols increased villus height, villus height/crypt depth, secretory immunoglobulin A (p > 0.05), and antioxidant enzymes, while decreasing MDA and apoptosis in the intestine (p > 0.05). However, compared with other groups, the content of T-AOC in jejunum did not change significantly (p > 0.05). Tea polyphenols also increased claudin-1 levels in the duodenum, jejunum, and ileum more than CTC (p > 0.05). CTC had a limited effect on the mRNA expression of Occludin and ZO-1, while tea polyphenols increased these in both the duodenum and ileum (p > 0.05).ConclusionThis study demonstrated that tea polyphenols can effectively improve the intestinal barrier of weaned lambs, and that they have anti-inflammatory and antioxidant effects similar to those of antibiotics. Thus, tea polyphenols could be used to replace antibiotics in ensuring safety of livestock products and in achieving the sustainable development of modern animal husbandry

Microbial Fuel Cell-Based Biosensor for Simultaneous Test of Sodium Acetate and Glucose in a Mixed Solution

Most microbial fuel cell (MFC) sensors only focus on the detection of mixed solutions with respect to the chemical oxygen demand (COD) or toxicity; however, the concentrations of the individual analytes in a mixed solution have rarely been studied. Herein, we developed two types of MFC sensors, adapted with sodium acetate (MFC-A) and glucose (MFC-B) as organic substrates in the startup period. An evident difference in the sensor sensitivities (the slope value of the linear-regression curve) was observed between MFC-A and MFC-B. MFC-A exhibited a superior performance compared with MFC-B in the detection of sodium acetate (4868.9 vs. 2202 mV/(g/L), respectively) and glucose (3895.5 vs. 3192.9 mV/(g/L), respectively). To further compare these two MFC sensors, the electrochemical performances were evaluated, and MFC-A exhibited a higher output voltage and power density (593.76 mV and 129.81 ± 4.10 mW/m2, respectively) than MFC-B (484.08 mV and 116.21 ± 1.81 mW/m2, respectively). Confocal laser scanning microscopy (CLSM) and microbial-community analysis were also performed, and the results showed a richer anode biomass of MFC-A in comparison with MFC-B. By utilizing the different sensitivities of the two MFC sensors towards sodium acetate and glucose, we proposed and verified a novel method for a simultaneous test on the individual concentrations of sodium acetate and glucose in a mixed solution. Linear equations of the two variables (concentrations of sodium acetate and glucose) were formulated. The linear equations were solved according to the output voltages of the two MFC sensors, and the solutions showed a satisfactory accuracy with regard to sodium acetate and glucose (relative error less than 20%)

Eliminating Voltage Decay of Lithium-Rich Li1.14Mn0.54Ni0.14Co0.14O2 Cathodes by Controlling the Electrochemical Process

A lithium-rich cathode material Li1.14Mn0.54Ni0.14Co0.14O2 (LNMCO) is prepared by a co-precipitation method. The issue of voltage decay in long-term cycling is largely eliminated by control of the charge-discharge voltage range. The LNMCO material exhibits 9.8% decay in discharge voltage over 200 cycles between 2.0-4.6 V, during which the working voltage decays significantly, from 3.57 V to 3.22 V. The decay was decelerated by a factor of six by using a voltage window of 2.0-4.4 V, from 3.53 V to 3.47 V. IR and Raman spectra reveal that the transformation of layered structure to spinel is significantly retarded under 2.0-4.4V cycling conditions. Transmission electron microscopy (TEM) was also applied for examining phase change in an individual particle during cycling, showing that the spinel phase occurs both at 2.0-4.6 V and at 2.0-4.4 V, but is not dominant in the latter. Normalization of Li can remove the additional impact on the voltage decay which is brought by different amounts of Li intercalation. The mechanism of no voltage decay at 2.0-4.4 V cycling is raised and electrochemical impedance spectrum data also support the hypothesis