High-efficiency electrodeposition of magnesium alloy-based anodes for ultra-stable rechargeable magnesium-ion batteries.

Rechargeable magnesium batteries (RMBs) have attracted much attention because of their high theoretical volumetric capacity and high safety. However, the uneven deposition behavior, harmful corrosion reaction and poor stability of magnesium metal anodes have hindered the practical application of RMBs. Herein, we propose a facile alloy electrodeposition method to construct an artificial layer on an Mg anode. Experimental results show that the polarization of the symmetric magnesium alloy-based (Mg-Sn@Mg and Mg-Bi@Mg) cells is significantly reduced (∼0.05 V) at a current density of 0.1 mA cm-2. The symmetric cells using the prepared Mg alloy anodes exhibited lower voltage hysteresis and ultra-stable cycling performance at a higher density of 1.0 mA cm-2 over 700 h. The in situ optical microscopy study clearly demonstrated that the Mg dendrite formation was successfully retarded by the designed Mg-Sn and Mg-Bi alloy artificial protective layer on Mg anodes. The superiority of Mg-Sn@Mg and Mg-Bi@Mg was further confirmed in full cells using Mo6S8 as the cathode. Compared with the Mo6S8//Mg full cell, the Mo6S8//Mg-Sn@Mg and Mo6S8//Mg-Bi@Mg full cells maintained an ultra-stable electrochemical performance even after 5000 cycles. This proof-of-concept provides a novel scope for the artificial coating layers on Mg anodes prepared by alloy electrodeposition and can be extended to other alloy anodes (i.e. Mg-Cu@Mg and so on). This work provides an avenue for the design of practical and high-performance RMBs and beyond.

Emerging Chemistry for Wide-Temperature Sodium-Ion Batteries.

The shortage of resources such as lithium and cobalt has promoted the development of novel battery systems with low cost, abundance, high performance, and efficient environmental adaptability. Due to the abundance and low cost of sodium, sodium-ion battery chemistry has drawn worldwide attention in energy storage systems. It is widely considered that wide-temperature tolerance sodium-ion batteries (WT-SIBs) can be rapidly developed due to their unique electrochemical and chemical properties. However, WT-SIBs, especially for their electrode materials and electrolyte systems, still face various challenges in harsh-temperature conditions. In this review, we focus on the achievements, failure mechanisms, fundamental chemistry, and scientific challenges of WT-SIBs. The insights of their design principles, current research, and safety issues are presented. Moreover, the possible future research directions on the battery materials for WT-SIBs are deeply discussed. Progress toward a comprehensive understanding of the emerging chemistry for WT-SIBs comprehensively discussed in this review will accelerate the practical applications of wide-temperature tolerance rechargeable batteries.

Effect of Heteroatom Doping on Electrochemical Properties of Olivine LiFePO4 Cathodes for High-Performance Lithium-Ion Batteries.

Lithium iron phosphate (LiFePO4, LFP), an olivine-type cathode material, represents a highly suitable cathode option for lithium-ion batteries that is widely applied in electric vehicles and renewable energy storage systems. This work employed the ball milling technique to synthesize LiFePO4/carbon (LFP/C) composites and investigated the effects of various doping elements, including F, Mn, Nb, and Mg, on the electrochemical behavior of LFP/C composite cathodes. Our comprehensive work indicates that optimized F doping could improve the discharge capacity of the LFP/C composites at high rates, achieving 113.7 mAh g-1 at 10 C. Rational Nb doping boosted the cycling stability and improved the capacity retention rate (above 96.1% after 100 cycles at 0.2 C). The designed Mn doping escalated the discharge capacity of the LFP/C composite under a low temperature of -15 °C (101.2 mAh g-1 at 0.2 C). By optimizing the doping elements and levels, the role of doping as a modification method on the diverse properties of LFP/C cathode materials was effectively explored.

Halogen chemistry of solid electrolytes in all-solid-state batteries.

All-solid-state batteries (ASSBs) using solid-state electrolytes, replacing flammable liquid electrolytes, are considered one of the most promising next-generation electrochemical energy storage devices because of their improved, inherent safety and energy density. A family of solid electrolytes incorporating halogens has attracted attention because of their potentially high ionic conductivity, good deformability and wide electrochemical windows. Although progress has been made for halogen-containing solid electrolytes (HSEs) in ASSBs, challenges in the preparations, characterizations and low-cost industrial scalability remain. In this Review, we focus on the development of halide battery chemistry, the preparation, modification and properties of HSEs, and issues with HSEs in ASSBs. The chemical action of halogen and ion transport mechanisms are discussed. Moreover, the main challenges and future development directions of halide-based ASSBs are discussed to pave the way for practical applications of HSEs for next-generation rechargeable batteries.

Adsorption Isotherms of Low-Pressure H2O on a Low-Temperature Surface Measured by a Quartz Crystal Microbalance.

The low-pressure gas in the vacuum plume produced by the chemical thrusters contaminates the spacecraft when adsorbed on the low-temperature surface. To provide theoretical support for further research on gaseous plume pollutants, the adsorption isotherms of low-pressure H2O were measured by a quartz crystal microbalance (QCM) at temperatures ranging from 233 to 273 K. The measured isotherms are similar to the type-I and type-II isotherms and have been correlated by various models (e.g., the Langmuir, Dubinin-Radushkevich, Brunauer-Emmett-Teller (BET), and universal models). It shows that the universal model has a great advantage in predicting the adsorption at a specific temperature point in our study. To estimate the adsorption at the continuous temperature range, the critical parameters of the multi-Langmuir model were expressed in semiempirical formulas. Since the normalized isotherms of H2O at different temperatures converge well, a simplified multi-Langmuir (SML) model was proposed. The experimental results at the temperature and pressure ranges we explored are consistent with the results predicted by the SML model, suggesting that the SML model is more suitable and convenient to predict the low-pressure adsorption of H2O for a continuous low-temperature range. Moreover, the low-pressure adsorption behaviors of H2O and CO2 on the low-temperature surface are compared and discussed.

Improving the viability and versatility of the E × B probe with an active cooling system.

A thermostatic E × B probe is designed to protect the probe body from the thermal effect of the plasma plume that has a significant influence on the resolution of the probe for high-power electric thrusters. An active cooling system, which consists of a cooling panel and carbon fiber felts combined with a recycling system of liquid coolants or an open-type system of gas coolants, is employed to realize the protection of the probe. The threshold for the design parameters for the active cooling system is estimated by deriving the energy transfer of the plasma plume-probe body interaction and the energy taken away by the coolants, and the design details are explained. The diagnostics of the LIPS-300 ion thruster with a power of 3 kW and a screen-grid voltage of 1450 V was implemented by the designed thermostatic E × B probe. The measured spectra illustrate that the thermostatic E × B probe can distinguish the fractions of Xe+ ions and Xe2+ ions without areas of overlap. In addition, the temperature of the probe body was less than 306 K in the beam region of the plasma plume during the 200-min-long continuous test. A thermostatic E × B probe is useful for enhancing the viability and versatility of equipment and for reducing uneconomical and complex test procedures.