Fluorine-Rich Electrolyte Additive for Achieving Dendrite-Free Lithium Anodes at Low Temperatures.

The practical application of lithium metal anodes is significantly impeded by poor interfacial stability and uncontrolled dendrite growth. Herein, we introduce methyl trifluoroacetate (MTFA), a low-melting-point small molecule, as an electrolyte additive in an ether-based electrolyte. This additive facilitates the formation of an in situ composite solid electrolyte interphase (SEI) layer that is rich in LiF and features an ester-based flexible matrix. The resulting composite layer exhibits high ionic conductivity and mechanical stability, effectively regulating the lithium deposition behavior over a broad temperature range and inhibiting dendrite formation. Based on MTFA, the Li||Li symmetrical cell achieves a lifespan exceeding 5000 h at room temperature and 800 h at -20 °C, both with ultralow overpotential and exceptional cycling stability. In Li||LiFePO4 full cells with a high-area loading (10.52 mg cm-2) and an N/P ratio of 1.68, an average capacity decay of merely 0.096% per cycle is observed over 200 cycles. Even at -20 °C, the Li||LiFePO4 cell shows a CE of over 99% and maintains stable cycling performance. This work provides an innovative approach for optimizing lithium metal anode interfaces and enhancing low-temperature operation capabilities through the use of electrolyte additives.

Tandem Catalysis inside Double-Shelled Nanocages with Separated and Tunable Atomic Catalyst Sites for High Performance Lithium-Sulfur Batteries.

Single-atomic catalysts are effective in mitigating the shuttling effect and slow redox kinetics of lithium polysulfides (LiPSs) in lithium-sulfur (Li-S) batteries, but their ideal performance has yet to be achieved due to the multi-step conversion of LiPSs requiring multifunctional active sites for tandem catalysis. Here double-shelled nano-cages (DSNCs) have been developed to address this challenge, featuring separated and tunable single-atom sites as nano reactors that trigger tandem catalysis and promote the efficient electrochemical conversion of LiPSs. This enables high capacity and durable Li-S batteries. The DSNCs, with inner Co-N4 and outer Zn-N4 sites (S/CoNC@ZnNC DSNCs), exhibit a high specific capacity of 1186 mAh g-1 at 1 C, along with a low capacity fading rate of 0.063% per cycle over 500 cycles. Even with a high sulfur loading (4.2 mg cm-2) and a low E/S ratio (6 µL mg-1), the cell displays excellent cycling stability. Moreover, the Li-S pouch cells are capable of stable cycling for more than 160 cycles. These results demonstrate the feasibility of driving successive sulfur conversion reactions with separated active sites, and are expected to inspire further catalyst design for high performance Li-S batteries.

Temporal Convolutional Network-Based Signal Detection for Magnetotactic Bacteria Communication System.

Molecular communication (MC) aims to use signaling molecules as information carriers to achieve communication between biological entities. However, MC systems severely suffer from inter symbol interference (ISI) and external noise, making it virtually difficult to obtain accurate mathematical models. Specifically, the mathematically intractable channel state information (CSI) of MC motivates the deep learning (DL) based signal detection methods. In this paper, a modified temporal convolutional network (TCN) is proposed for signal detection for a special MC communication system which uses magnetotactic bacteria (MTB) as information carriers. Results show that the TCN-based detector demonstrates the best overall performance. In particular, it achieves better bit error rate (BER) performance than sub-optimal maximum a posteriori (MAP) and deep neural network (DNN) based detectors. However, it behaves similarly to the bidirectional long short term memory (BiLSTM) based detector that has been previously proposed and performs worse than the optimal MAP detector. When both BER performance and computational complexity are taken into account, the proposed TCN-based detector outperforms BiLSTM-based detectors. Furthermore, in terms of robustness evaluation, the proposed TCN-based detector outperforms all other DL-based detectors.

In Situ Construction of Composite Artificial Solid Electrolyte Interphase for High-Performance Lithium Metal Batteries.

Lithium metal is considered as the most promising anode material for high energy density secondary batteries due to its high theoretical specific capacity and low redox potential. However, poor interfacial stability and uncontrollable dendrite growth seriously hinder the commercial application of Li metal anodes. Herein, we constructed a composite artificial solid-electrolyte interphase (ASEI) utilizing the in situ reaction between polyacrylic acid (PAA)/stannous fluoride (SnF2) and lithium metal, which spontaneously generates LiPAA, LiF, and Li5Sn2 alloys. The in situ formed LiPAA as a flexible matrix can accommodate the volume change of the lithium anode. Meanwhile, LiF and Li5Sn2 play the roles for improving the mechanical properties and boosting Li-ion flux in the interfacial layer, respectively. Benefiting from the ingenious design, the PAA-SnF2@Li anodes remain stable and dendrite-free morphology in symmetric cells for over 2000 h and exhibit excellent cycling stability in high-area loading (10.52 mg cm-2) Li||LiFePO4 full cells with a N/P of 1.68, which endures only 0.11% average capacity decay per cycle in 200 cycles. This simple and low-cost method supplies a route for the commercial application of lithium metal anodes with fresh eyes.

Photothermal Sensing of Nano-Devices Made of Graphene Materials.

Graphene is widely used as the basic materials of nano optical devices and sensors on account of its special structures and excellent photoelectric properties. Graphene is considered as an ideal material for photodetectors because of its ultra-wide absorption spectrum from the ultraviolet to the terahertz band, ultrahigh carrier mobility and ultrafast photoreaction speed. In this study, a photothermal nano-device was made using graphene that was transferred to an electrode using an all-dry viscoelastic stamping method. The nano-device has the advantages of simplicity, high efficiency and instant measurement. This nano-device was used to measure the light absorption of graphene, and the calculated light absorption rate of graphene is basically consistent with previous research results. Experiments on irradiation at different wavelengths and thermal heating at different temperatures show that the nano-device has an excellent response to near-infrared and mid-infrared light. The conclusions provide an experimental basis for the research, design and fabrication of nano-devices, and this device can provide an effective method for detecting light and temperature in areas such as electronic components and solar cells.

Complete synchronization of temporal Boolean networks.

This letter studies complete synchronization of two temporal Boolean networks coupled in the drive-response configuration. Necessary and sufficient conditions are provided based on the algebraic representation of Boolean networks. Moreover, the upper bound to check the criterion is given. Finally, an illustrative example shows the efficiency of the proposed results.