Insight into the Contribution of the Electrolyte Additive LiBF4 in High-Voltage LiCoO2||SiO/C Pouch Cells.

High-voltage pouch cells using an LiCoO2 cathode and SiO/C anode are regarded as promising energy storage devices due to their high energy densities. However, their failure is associated with the unstable, high-impedance cathode electrolyte interphase (CEI) film on the cathode and the solid electrolyte interphase (SEI) film on the anode surface, which hinder their practical use. Here, we report a novel approach to ameliorate the above challenges through the rational construction of a stable, low-impedance cathode and anode interface film. Such films are simultaneously formed on both electrodes via the participation of the traditional salt, lithium tetrafluoroborate (LiBF4), as electrolyte additive. The application of 1.0% LiBF4 enhances the capacity retention of the cell from 26.1 to 82.2% after 150 cycles between 3.0 and 4.4 V at 1 C. Besides, the low-temperature discharge performance is also improved by LiBF4 application: the discharge capacity of the cell with LiBF4 is 794 mAh compared with 637 mAh without LiBF4 at 1 C and -20 °C. The excellent electrochemical performance of pouch cells is ascribed to the contribution of LiBF4. Especially, the low binding energy of LiBF4 with the oxygen on the LiCoO2 surface leads to the enrichment of LiBF4 that forms the protective cathode interface, which fills the blanks of previous research.

Sulfur-Rich Additive-Induced Interphases Enable Highly Stable 4.6†V LiNi0.5 Co0.2 Mn0.3 O2 ||graphite Pouch Cells.

High-voltage lithium-ion batteries (LIBs) have attracted great attention due to their promising high energy density. However, severe capacity degradation is witnessed, which originated from the incompatible and unstable electrolyte-electrode interphase at high voltage. Herein, a robust additive-induced sulfur-rich interphase is constructed by introducing an additive with ultrahigh S-content (34.04 %, methylene methyl disulfonate, MMDS) in 4.6 V LiNi0.5 Co0.2 Mn0.3 O2 (NCM523)||graphite pouch cell. The MMDS does not directly participate the inner Li+ sheath, but the strong interactions between MMDS and PF6 - anions promote the preferential decomposition of MMDS and broaden the oxidation stability, facilitating the formation of an ultrathin but robust sulfur-rich interfacial layer. The electrolyte consumption, gas production, phase transformation and dissolution of transition metal ions were effectively inhibited. As expected, the 4.6 V NCM523||graphite pouch cell delivers a high capacity retention of 87.99 % even after 800 cycles. This work shares new insight into the sulfur-rich additive-induced electrolyte-electrode interphase for stable high-voltage LIBs.

Online Learning Koopman Operator for Closed-Loop Electrical Neurostimulation in Epilepsy.

Electrical neuromodulation as a palliative treatment has been increasingly used in the control of epilepsy. However, current neuromodulations commonly implement predetermined actuation strategies and lack the capability of self-adaptively adjusting stimulation inputs. In this work, rooted in optimal control theory, we propose a Koopman-MPC framework for real-time closed-loop electrical neuromodulation in epilepsy, which integrates i) a deep Koopman operator based dynamical model to predict the temporal evolution of epileptic electroencephalogram (EEG) with an approximate finite-dimensional linear dynamics and ii) a model predictive control (MPC) module to design optimal seizure suppression strategies. The Koopman operator based linear dynamical model is embedded in the latent state space of the autoencoder neural network, in which we can approximate and update the Koopman operator online. The linear dynamical property of the Koopman operator ensures the convexity of the optimization problem for subsequent MPC control. The proposed deep Koopman operator model shows greater predictive capability than the baseline models (e.g., vector autoregressive model, kernel based method and recurrent neural network (RNN)) in both synthetic and real epileptic EEG data. Moreover, compared with the RNN-MPC framework, our Koopman-MPC framework can suppress seizure dynamics with better computational efficiency in both the Jansen-Rit model and the Epileptor model. Koopman-MPC framework opens a new window for model-based closed-loop neuromodulation and sheds light on nonlinear neurodynamics and feedback control policies.

[Effect of urotensin II on the nitric oxide production in neonatal rat cardiomyocytes].

The aim of this study was to investigate the effect of urotensin II (U II) on the nitric oxide (NO) production in cultured neonatal rat cardiomyocytes. The endothelial nitric oxide synthase (eNOS) mRNA expression was assessed by semi-quantitative reverse transcription-polymerase chain reaction. The activity of nitric oxide synthase (NOS) and NO content in cardiomyocytes were measured. The current results showed that U inhibited eNOS mRNA expression, the NOS activity and the NO production of cardiomyocytes. U II (0.1 micromol/L) inhibited the NOS activity and the NO production in cardiomyocytes in a time-dependent manner. These results suggest that the cardiovascular effect of U II might be partially associated with NO production in cultured neonatal rat cardiomyocytes.