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As a new class of lithium rich cathodes, disordered rock-salt cathodes have been of primary interest, because of their ability to deliver a promisingly high capacity up to 300 mA h/g. Nevertheless, some fundamental issues are yet to be fully understood and a comprehensive mastering of their solid-state chemistry, kinetics and thermal stability is required. Here, we select a high capacity cation-disordered positive electrode- Li1.2Ni0.4Nb0.4O2 as a model compound to study intrinsic reaction mechanism, including charge compensation mechanism, kinetics, thermal stability, and structural evolution. By combining soft and hard X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS) with operando and ex-situ differential scanning calorimetry (DSC), galvanostatic intermittent titration technique (GITT), cyclic voltammetry (CV), and X-ray diffraction (XRD), we present holistic information on disordered rock-salt cathode. This work provides beneficial insights into designing and tailoring new positive electrodes with disordered rock-salt structure.

Computer simulations were performed on the spontaneous solidification and artificial intervention solidification processes of liquid gallium (Ga) by using molecular dynamics. The formation and evolution mechanism of the microstructure of liquid Ga under different solidification conditions were systematically studied using a combination of microstructural methods including the pair distribution function, bond-type index, and cluster-type index. The simulation results revealed that spontaneous homogeneous nucleation started from icosahedrons and defective icosahedrons. Artificial intervention can effectively control the thermostatic crystallization processes of liquid Ga, favoring crystal formation with large grains. The simulation results explain important experimental phenomena and the solidification theory of Ga smelting by the crystallization method from the microscopical point of view. We tested experimentally the process conditions for high-purity Ga smelting by the crystallization method as obtained from our simulations, resulting in successful preparation of metallic Ga with purity of 99.99999%.

In this study, poly-toluene isomers, such as poly(o-toluidine), poly(m-toluidine), and poly(p-toluidine), (abbreviated as POT, PMT, and PPT, respectively), were investigated for the corrosion protection of mild steel in 3.5% NaCl. The polymers were prepared by chemical oxidation and characterized by Fourier-transform infrared spectroscopy, UV–visible spectroscopy, x-ray diffraction, cyclic voltammetry, and scanning electron microscopy. The corrosion inhibition abilities of these coatings were evaluated by polarization and electrochemical impedance spectroscopy in aqueous NaCl solution. The results of this study showed that the inhibition efficiency of PMT reached 82.1%, which was greater than those of POT and PPT with 74.5% and 69.2%, respectively. In addition, the corresponding corrosion rates of PMT, POT, and PPT are 1.3 × 10−4 mm/year, 1.0 × 10−3 mm/year, and 4.1 × 10−2 mm/year, respectively. All these data reveal excellent properties of PMT in terms of corrosion protection.

Anatase TiO2 nanospheres (ATNSs) were successfully prepared through a facile solvothermal method followed by a thermal treatment. The sample was characterized by scanning electrons microscopy, transmission electron microscopy, x-ray diffraction, Raman spectrum and nitrogen adsorption techniques. When tested as an anode material for sodium-ion batteries, the electrode of ATNSs delivered a large discharge capacity of 208 mAh g−1 after 100 cycles at a current density of 50 mA g−1, indicating excellent cycling performance. This could be attributed to the uniform structure of the nanospheres with large surface area and porous nature, providing more active sites, buffering volume change, and facilitating the sodium ion intercalation as well as rapid diffusion during the charge/discharge process. Cyclic voltammetry demonstrated that the sodium storage mechanism is mainly controlled by pseudocapacitive behavior, resulting in a large capacity and outstanding cycling stability.

Porous hard carbon with large interlayer distance was fabricated from walnut shells through a facile high-temperature pyrolysis process and investigated as an anode material for sodium-ion batteries (SIBs). The results show that the electrochemical performance is mainly dependent on the pyrolysis temperature. The porous hard carbon, which was carbonized at 1300°C, displays the highest reversible capacity of 230 mAh g−1 at 20 mA g−1 and an excellent cycling stability (96% capacity retained over 200 cycles). The promising electrochemical performances are attributed to the porous structure reducing distances for sodium ion diffusion and expanded interlayer spacing, which is beneficial for sodium reversible insertion/extraction. The excellent electrochemical performance as well as the low-cost and environmental friendliness demonstrates that walnut shell-derived porous hard carbon is a promising anode material candidate for SIBs.

Thermal safety concerns of lithium ion batteries (LIBs) need to be solved urgently to facilitate their large-scale applications. Introducing safer anode materials can suppress the thermal runaway initiation but is usually compromising the cell performance due to their induced lower energy density. In this work, Ti3C2Tz MXene with tailored surface terminating groups is identified to be a safer LIB anode with improved capacity and lower operational potential. Calorimetric analyses demonstrate its significantly reduced heat generation (204 J g−1) with electrolyte compared to conventional graphite anode (995 J g−1). Detailed characterizations and thermal analyses reveal the great dependence of its thermal behavior on the lithiation states, surface morphology, and surface-terminating functional groups. Modifying the Ti3C2Tz surface functional groups via annealing can eliminate the irreversible lithium metal plating, which mitigates the parasitic exothermic reactions during thermal runaway and enhances the anode initial coulombic efficiency and cycling stability. The in-situ thermal analyses of LIB full cells demonstrate the obviously improved onset temperature of thermal runaway (195 °C) from the modified Ti3C2Tz-lithium cobalt oxide (LCO) full cell than the graphite-LCO full cell (169 °C), indicating a much safer LIB developed.

Organic cathode materials have attracted widespread attention due to their diverse structures, abundant raw materials, low cost, and eco-friendliness. However, their practical applications are restricted because of the poor cycling stability and lifespan owing to the dissolution and shuttle effect of the organic cathode in the liquid electrolyte. In this work, a novel all-solid-state Li-organic battery with ultralong lifespan is developed by using perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) as the organic cathode, composite solid polymer electrolyte (hybrid polymer-LiTFSI-LLZTO, HLL) as the electrolyte, and Li metal as the anode. The as-prepared HLL electrolyte exhibits high ionic conductivity (1.46 × 10-4 S cm−1 at 30 °C), superior thermal stability (~202 °C), outstanding electrode/electrolyte interfacial compatibility, and significant suppression to the dissolution/shuttle of PTCDA and the growth of Li dendrite. Ascribing to these advantages, the solid-state PTCDA|HLL|Li battery delivers a reversible capacity of 60 mAh g−1 after 1000 cycles at a high current density of 500 mA g−1, corresponding to an outstanding capacity retention of 91%. Moreover, the solid-state PTCDA|Li battery presents an elevated thermal stable window (178 °C) and less heat release (430 J g−1) compared with the analogous battery using liquid electrolyte (151 °C and 486 J g−1). Furthermore, the solid-state battery exhibits desirable flexibility and satisfactory safety under various abuse conditions (bending, cutting, and punching), demonstrating its outstanding safety in practical environments. This work offers a new pathway toward safer, longer lifespan solid-state Li-organic batteries.

The low room-temperature ionic conductivity, narrow voltage window, and poor thermal stability of solid polymer electrolyte hinder the application of high energy density, safer solid-state lithium batteries (SLBs). Hence, we developed a novel composite solid polymer electrolyte (CSPE) with high room-temperature ionic conductivity (2.4 × 10−4 S cm−1), wide voltage window (~4.8 V), and excellent thermal stability (~330 °C) by combining Li6.4La3Zr1.4Ta0.6O12 ceramic filler with poly(vinylidene fluoride) (PVDF) polymer and bis(trifluoromethane)sulfonimide lithium (LiTFSI) salt. Free-standing, scalable, and mechanically robust CSPE separately coupled with LiFePO4 and high-voltage LiNi1/3Co1/3Mn1/3O2 cathodes vs lithium anode demonstrated stable cycling. More importantly, we in-situ measured the thermal stable window (177 °C) with a small heat release (189 J g−1) during the thermal runaway of the entire CSPE coin cell. In contrast, the liquid electrolyte cell delivered a depressing thermal stable window (157 °C) and release a significant amount of heat (812 J g−1). The superior thermal safety of CSPE cell can be ascribed to the solid-state property and outstanding thermal stability of the CSPE. Most notably, this work not only proposes a promising CSPE but also highlights a reference for in-situ quantitative study on the thermal safety of entire SLBs.