Easy processing and flexibility of polymer electrolytes make them very promising in developing all-solid-state lithium batteries. However, their low room-temperature conductivity and poor mechanical and thermal properties still hinder their applications. Here, we use LiLaZrTaO (LLZTO) ceramics to trigger structural modification of poly(vinylidene fluoride) (PVDF) polymer electrolyte. By combining experiments and first-principle calculations, we find that La atom of LLZTO could complex with the N atom and C═O group of solvent molecules such as N,N-dimethylformamide along with electrons enriching at the N atom, which behaves like a Lewis base and induces the chemical dehydrofluorination of the PVDF skeleton. Partially modified PVDF chains activate the interactions between the PVDF matrix, lithium salt, and LLZTO fillers, hence leading to significantly improved performance of the flexible electrolyte membrane (e.g., a high ionic conductivity of about 5 × 10 S cm at 25 °C, high mechanical strength, and good thermal stability). For further illustration, a solid-state lithium battery of LiCoO|PVDF-based membrane|Li is fabricated and delivers satisfactory rate capability and cycling stability at room temperature. Our study indicates that the LLZTO modifying PVDF membrane is a promising electrolyte used for all-solid-state lithium batteries.

Polymer‐based electrolytes have attracted ever‐increasing attention for all‐solid‐state lithium (Li) metal batteries due to their ionic conductivity, flexibility, and easy assembling into batteries, and are expected to overcome safety issues by replacing flammable liquid electrolytes. However, it is still a critical challenge to effectively block Li dendrite growth and improve the long‐term cycling stability of all‐solid‐state batteries with polymer electrolytes. Here, the interface between novel poly(vinylidene difluoride) (PVDF)‐based solid electrolytes and the Li anode is explored via systematical experiments in combination with first‐principles calculations, and it is found that an in situ formed nanoscale interface layer with a stable and uniform mosaic structure can suppress Li dendrite growth. Unlike the typical short‐circuiting that often occurs in most studied poly(ethylene oxide) systems, this interface layer in the PVDF‐based system causes an open‐circuiting feature at high current density and thus avoids the risk of over‐current. The effective self‐suppression of the Li dendrite observed in the PVDF–LiN(SO2F)2 (LiFSI) system enables over 2000 h cycling of repeated Li plating–stripping at 0.1 mA cm−2 and excellent cycling performance in an all‐solid‐state LiCoO2||Li cell with almost no capacity fade after 200 cycles at 0.15 mA cm−2 at 25 °C. These findings will promote the development of safe all‐solid‐state Li metal batteries.

Developing high-performance film dielectrics for capacitive energy storage has been a great challenge for modern electrical devices. Despite good results obtained in lead titanate-based dielectrics, lead-free alternatives are strongly desirable due to environmental concerns. Here we demonstrate that giant energy densities of ~70 J cm−3, together with high efficiency as well as excellent cycling and thermal stability, can be achieved in lead-free bismuth ferrite-strontium titanate solid-solution films through domain engineering. It is revealed that the incorporation of strontium titanate transforms the ferroelectric micro-domains of bismuth ferrite into highly-dynamic polar nano-regions, resulting in a ferroelectric to relaxor-ferroelectric transition with concurrently improved energy density and efficiency. Additionally, the introduction of strontium titanate greatly improves the electrical insulation and breakdown strength of the films by suppressing the formation of oxygen vacancies. This work opens up a feasible and propagable route, i.e., domain engineering, to systematically develop new lead-free dielectrics for energy storage.

We report on the formation, structure, electrochemical properties and stability of trichrome process coatings (TCP) on AA2024-T3. The coating is 50–100 nm thick and forms over most of the alloy surface. It consists of hydrated zirconia (ZrO2•2H2O) and its formation under open circuit conditions is driven by an increase in the interfacial pH caused by (i) dissolution of the oxide layer and (ii) oxygen reduction mainly at the Cu-rich intermetallics. The coating appears biphasic with a hydrated zirconia overlayer and a fluoroaluminate interfacial layer (KxAlF3 + x). Cr(III) oxide is coprecipitated with the hydrated zirconia with Cr-rich regions in and around pits. Some anodic and cathodic protection is provided by physically blocking Al-rich sites (oxidation) and Cu-rich IMCs (reduction). This is evidenced by a 10 × greater polarization resistance, Rp, for the TCP-coated alloys, and suppressed anodic and cathodic currents (air saturated 0.5 M Na2SO4, room temperature) in potentiodynamic polarization scans. In the short-term (4-h immersion), the coating is stable, as evidenced by unchanging passivation performance. While no Cr(VI) species were detected in the coating immediately after formation, Raman spectroscopy revealed consistent evidence for transient formation of Cr(VI) species in the coating after immersion in different air-saturated electrolyte solutions from 1–14 days.

Highly Li-ion conductive Li6PS5Cl solid-state electrolytes (SSEs) were prepared by solid-state sintering method. The influence of sintering temperature and duration on the phase, ionic conductivity, and activation energy of Li6PS5Cl was systematically investigated. The Li6PS5Cl electrolyte with a high ionic conductivity of 3.15 × 10–3 S cm–1 at room temperature (RT) was obtained by sintering at 550 °C for just 10 min, which was more efficient taking into account such a short preparation time in comparison with other reported methods to synthesize Li6PS5Cl SSEs. All-solid-state lithium sulfur batteries (ASSLSBs) based on the Li6PS5Cl SSE were assembled by using the nano-sulfur/multiwall carbon nanotube composite combined with Li6PS5Cl as the cathode and Li–In alloy as the anode. The cell delivered a high discharge capacity of 1850 mAh g–1 at RT for the first full cycle at 0.176 mA cm–2 (∼0.1C). The discharge capacity was 1393 mAh g–1 after 50 cycles. In addition, the Coulombic efficiency remained nearly 100% during galvanostatic cycling. The experimental data showed that Li6PS5Cl was a good candidate for the SSE used in ASSLSBs.

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The electronic structures, formation energies, and band edge positions of anatase TiO2 doped with transition metals have been analyzed by ab initio band calculations based on the density functional theory with the planewave ultrasoft pseudopotential method. The model structures of transition metal-doped TiO2 were constructed by using the 24-atom 2 × 1 × 1 supercell of anatase TiO2 with one Ti atom replaced by a transition metal atom. The results indicate that most transition metal doping can narrow the band gap of TiO2, lead to the improvement in the photoreactivity of TiO2, and simultaneously maintain strong redox potential. Under O-rich growth condition, the preparation of Co-, Cr-, and Ni-doped TiO2 becomes relatively easy in the experiment due to their negative impurity formation energies, which suggests that these doping systems are easy to obtain and with good stability. The theoretical calculations could provide meaningful guides to develop more active photocatalysts with visible light response.

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