The rechargeable aprotic lithium-air (Li-O2) battery is a promising potential technology for next-generation energy storage, but its practical realization still faces many challenges. In contrast to the standard Li-O2 cells, which cycle via the formation of Li2O2, we used a reduced graphene oxide electrode, the additive LiI, and the solvent dimethoxyethane to reversibly form and remove crystalline LiOH with particle sizes larger than 15 micrometers during discharge and charge. This leads to high specific capacities, excellent energy efficiency (93.2%) with a voltage gap of only 0.2 volt, and impressive rechargeability. The cells tolerate high concentrations of water, water being the dominant proton source for the LiOH; together with LiI, it has a decisive impact on the chemical nature of the discharge product and on battery performance.

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The use of a magic-angle turning and phase-adjusted spinning sideband NMR experiment to resolve and quantify the individual local environments in the high field (7)Li and (31)P NMR spectra of paramagnetic lithium-ion battery materials is demonstrated. The use of short radio frequency pulses provides an excitation bandwidth that is sufficient to cover shift anisotropy of >1 MHz in breadth, allowing isotropic and anisotropic components to be resolved.

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Optical force, coming from momentum exchange during light-matter interactions, has been widely utilized to manipulate microscopic objects, though mostly in vacuum or in liquids. By contrast, due to the light-induced thermal effect, photophoretic force provides an alternative and effective way to transport light-absorbing particles in ambient gases. However, in most cases these forces work independently. Here, by employing the synergy of optical force and photophoretic force, we propose and experimentally demonstrate a configuration which can drive a micron-size metallic plate moving back and forth on a tapered fiber with supercontinuum light in ambient air. Optical pulling and oscillation of the metallic plate are experimentally realized. The results might open exhilarating possibilities in applications of optical driving and energy conversion.

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Li−Fe antisite defects are commonly found in LiFePO 4 particles and can impede or block Li diffusion in the single-file Li diffusion channels. However, due to their low concentration (∼1%), the effect of antisite defects on Li diffusion has only been systematically investigated by theoretical approaches. In this work, the exchange between Li in solid LiFePO 4 (92.5% enriched with 6 Li) and Li in the liquid Li electrolyte solution (containing natural abundance Li, 7.6% 6 Li and 92.4% 7 Li) was measured as a function of time by both ex situ and in situ solid-state nuclear magnetic resonance experiments. The experimental data reveal that the time dependence of the isotope exchange cannot be modeled by a simple single-file diffusion process and that defects must play a role in the mobility of ions in the LiFePO 4 particles. By performing kinetic Monte Carlo simulations that explicitly consider antisite defects, which allow Li to cross over between adjacent channels, we show that the observed tracer exchange behavior can be explained by the presence of channels with paired Li−Fe antisite defects. The simulations suggest that Li diffusion across the antisite is slow (10 −16 cm 2 s −1 ) and that the presence of antisite defects is widespread in the LiFePO 4 particles we examined, where ∼80% channels are affected by such defects.