RESUMO
Solid polymer electrolytes suffer from the low ionic conductivity and poor capability of suppressing lithium dendrites, which have greatly hindered the practical application of solid-state lithium-metal batteries. Here, we report a novel laponite sheet (LS) with a large negatively charged surface as an additive in a solid composite electrolyte (poly(ethylene oxide)-LS) to rearrange the lithium-ion environment and enhance the mechanical strength of the electrolytes (PEO-LS). The strong electrostatic regulation of laponite sheets assists the dissociation of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and constructs multiple transport channels for free lithium ions, achieving a high ionic conductivity of 1.1 × 10-3 S cm-1 at 60 °C. Furthermore, LS facilitates the in situ formation of a LiF-rich interface because of the boosting TFSI- anion concentration, which significantly suppresses lithium dendrites and prevents short circuit. As a result, the assembled LiFePO4|PEO-LS|Li battery demonstrates a long cycle life of over 800 cycles and a high Coulombic efficiency of 99.9% at 1C and 60 °C. When paired with a high-voltage NCM811 cathode, the battery also demonstrates excellent cycling stability and rate capability.
RESUMO
Practical applications of polymer electrolytes in lithium (Li) metal batteries with high-voltage Ni-rich cathodes have been hindered by the dendrite growth and poor oxidative stability of electrolytes. Herein, a self-healing polymer electrolyte is developed by in situ copolymerization of 2-(3-(6-methyl4-oxo-1,4-dihydropyrimidin-2-yl)ureido)ethyl methacrylate (UPyMA) and ethylene glycol methyl ether acrylate (EGMEA) monomers. With the electrolyte, the dendrite growth is inhibited by spontaneously repairing dendrite-induced defects, cracks, and voids at the Li/electrolyte interface; the suppressed dendrite growth and associated electro-chemo behaviors are visualized by the kinetic Mont-Carlo simulation. Benefitting from the high ionic conductivity, wide electrochemical window and good interfacial stability, the self-healing polymer electrolyte enables stable cycling of the LiNi0.8 Mn0.1 Co0.1 O2 (NMC811) cathode under 4.7 V, achieving a high specific capacity of ≈228.8 mAh g-1 and capacity retention of 80.4% over 500 cycles. The new electrolyte is very promising for developing highly safe and dendrite-free Li metal batteries with high energy density.
RESUMO
OBJECTIVE: This systematic review and meta-analysis aimed to evaluate the effects of mirror therapy on phantom limb sensation and phantom limb pain in amputees. DATA SOURCES: Nine electronic databases (PubMed, EMBASE, MEDLINE, Web of Science, the Cochrane Library, CINAHL, PsycInfo, PreQuest, PEDro) were searched from their inception to May 10th, 2021. METHODS: Two authors independently selected relevant studies and extracted the data. The effect sizes were calculated under a random-effects model meta-analysis, and heterogeneity was assessed using the I2 test. The risk of bias was evaluated by the Cochrane risk of bias tool, and the methodological quality was appraised by the PEDro scale. The GRADE approach was applied to assess the confidence of the effect. RESULTS: A total of 11 RCTs involving 491 participants were included in this review and nine RCTs involving 372 participants were included in meta-analysis. The quality of these studies was from poor to good with scores ranging from 2 to 8 points according to PEDro scale. The pooled SMD showed that mirror therapy reduced the pain with a large effect size (-0.81; 95% CI = -1.36 to -0.25; P = 0.005; I2 = 82%; n = 372) compared with other methods (four covered mirror, one phantom exercise, three mental visualization, one sensorimotor exercise, one transcutaneous electrical nerve stimulation, one tactile stimuli). The quality of evidence for the outcome pain intensity was determined to be fair according to GRADE approach. CONCLUSION: There is fair-quality evidence that MT is beneficial for reducing phantom limb pain.
