Elemental Si has a high theoretical capacity and has attracted attention as an anode material for high energy density lithium-ion batteries. Rapid capacity fading is the main problem with Si-based electrodes; this is mainly because of a massive volume change in Si during lithiation–delithiation. Here, we report that combining an ionic-liquid electrolyte with a charge capacity limit of 1000 mA h g–1 significantly suppresses Si volume expansion, improving the cycle life. Phosphorus-doping of Si also enhances the suppression and increases the Li+ diffusion coefficient. In contrast, the Si layer expands significantly in an organic electrolyte even with the charge capacity limit and even in an ionic-liquid electrolyte without the limit. We demonstrated that the homogeneously distributed Si lithiation–delithiation, phase-transition control from the Si to Li-rich Li–Si alloy phases, formation of a surface film with structural and/or mechanical stability, and faster Li+ diffusion contribute to suppressing Si volume expansion.

Background Based on epidemiological and experimental studies, type 2 diabetes mellitus (T2DM), especially insulin resistance that comprises the core mechanism of T2DM, has been recognized as a significant risk factor for Alzheimer’s disease (AD). Studies in humans and diabetic AD model mice have indicated a correlation between insulin resistance and increased amyloid deposition in the brain. Paradoxically, mice with targeted disruption of genes involved in the insulin signaling pathway showed protective effects against the AD-related pathology. These conflicting observations raise an issue as to the relationship between dysregulation of insulin signaling and AD pathophysiology. Methods To study the causal relations and molecular mechanisms underlying insulin resistance-induced exacerbation of amyloid pathology, we investigated the chronological changes in the development of insulin resistance and amyloid pathology in two independent insulin-resistant AD mouse models, i.e., long-term high-fat diet (HFD) feeding and genetic disruption of Irs2 , in combination with dietary interventions. In addition to biochemical and histopathological analyses, we examined the in vivo dynamics of brain amyloid-β (Aβ) and insulin by microdialysis technique. Results HFD-fed diabetic AD model mice displayed a reduced brain response to peripheral insulin stimulation and a decreased brain to plasma ratio of insulin during the hyperinsulinemic clamp. Diet-induced defective insulin action in the brain was accompanied by a decreased clearance of the extracellular Aβ in vivo and an exacerbation of brain amyloid pathology. These noxious effects of the HFD both on insulin sensitivity and on Aβ deposition in brains were reversibly attenuated by dietary interventions. Importantly, HFD feeding accelerated Aβ deposition also in the brains of IRS-2-deficient AD mice. Conclusions Our results suggested a causal and reversible association of brain Aβ metabolism and amyloid pathology by diet-dependent, but not genetically-induced, insulin-resistance. These observations raise the possibility that the causal factors of insulin resistance, e.g., metabolic stress or inflammation induced by HFD feeding, but not impaired insulin signaling per se, might be directly involved in the acceleration of amyloid pathology in the brain. Electronic supplementary material The online version of this article (10.1186/s13024-019-0315-7) contains supplementary material, which is available to authorized users.

The relationships between the natural variability and CO 2 -induced response over the Pacific region are investigated in terms of the spatial anomaly pattern of SST, sea level pressure and precipitation by a multi-model intercomparison analysis, based on the 18-model results contributing to the IPCC Fourth Assessment Report. The analysis indicates that the CO 2 -induced response pattern is related with the model natural variability modes, ENSO and AO. In the tropical Pacific, an ENSO-like global warming pattern is simulated by the majority of the models, with mostly El Niñ o-like change. In the Arctic region, an AO-like global warming pattern is simulated by many models, with the positive definite AO-phase change, if AO-like. It is suggested that the increase in meridional temperature gradient in the upper troposphere, and the lower stratosphere, provides a preferable condition for the positive AO-like change in the high latitudes by intensifying the subtropical jet, while the increase in the static stability provides a preferable condition for the El Niñ o-like change in the low latitudes, by reducing the large-scale ambient circulations. However, the sign of the mass (SLP) anomaly is incompatible over the North Pacific, between the positive AO-like change and the El Niñ o-like change. As a result, the present models cannot fully determine the relative importance between the mechanisms inducing the positive AO-like change and inducing the ENSO-like change, leading to scattering in global warming patterns in regional scales over the North Pacific.

Excellent cycling performance of an electrode composed of silicon alone was achieved in a bis(fluorosulfonyl)amide (FSA)‐based electrolyte, with a high discharge capacity of 950 mA h g−1 observed even at the 500th cycle. To elucidate the reaction behavior of the Si electrode in an FSA‐based ionic liquid electrolyte, we investigated the change in the cross‐sectional morphology of the Si‐active material layer, the distribution of Li in the layer, and the crystallinity of Si on the electrode surface. By cross‐sectional scanning electron microscopy, we confirmed that the electrode thickness increased with the cycle number. The increase in thickness was less noticeable in the FSA‐based electrolyte than in an organic electrolyte. An elemental analysis of the electrode material revealed that a film derived from the electrolyte was formed not only on the surface but also inside of the electrode. Soft X‐ray emission spectroscopy demonstrated that the distribution of Li in the FSA‐based electrolyte was more uniform for the cross‐section of the cycled electrode compared to that in an organic electrolyte. The results of Raman spectroscopy indicated that domains of amorphous Si were homogeneously distributed on the electrode surface in the FSA‐based electrolyte. The uniform distribution of the lithiation−delithiation reaction should help to suppress disintegration of the active material layer.