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Alumina powders have been widely used in lithium-ion batteries such as separator coating, electrode surface modification and electrolyte fillers. Rod-like alumina with its special aspect ratio is expected to open up a new application direction. In this work, alumina nanorods were prepared by a facile hydrothermal method. The aspect ratio and morphology of alumina nanorods were optimized by adjusting the hydrothermal temperature, hydrothermal synthesis time, volume ratio, directing agent, and sintering temperature. γ-Al2O3 nanorods with a diameter of 200–300 nm and a mean length of 5 μm and α-Al2O3 with a diameter of 100–200 nm and mean length of 5 μm were obtained by calcining the alumina precursor (AACH) at 800 °C and 1200 °C, respectively. The prepared alumina nanorods were added into polymer solid electrolyte, which promoted the dissociation of the lithium salt and stabilized the propylene polycarbonate (PPC) polymer, resulting in an improved potential window (4.5 V) and ionic conductivity (3.7 × 10−4 S/cm) of the PPC-based polymer solid electrolyte (SE). An NCM622/SE/Li solid-state battery showed enhanced electrochemical performance at ambient temperature with an initial discharge capacity of 188.5 mAh/g and a retention capacity of 158.1 mAh/g after 200 cycles at a current density of 0.5 C. These alumina nanorods have potential to be widely used in high-performance solid electrolytes.

Surface lithiated TiO2 nanorods were prepared by hydrothermal method. The surface lithiated TiO2 nanorods were firstly used in polymer solid electrolyte. The solid electrolyte shows excellent room‐temperature performance.

Low ionic conductivity at room temperature and poor interfacial compatibility are the main obstacles to restrain the practical application of polymer solid electrolytes. In this work, lanthanum zirconate (LZO) fibers were prepared by electrospinning method and used for the first time as fillers in sandwich polypropylene carbonate (PPC)-based solid electrolyte. Meanwhile, a graphite coating was applied on one surface of the composite solid electrolyte (CSE) membrane. The results show that the LZO fibers significantly increases the room-temperature electrochemical performance of the CSE, and the graphite coating enhances the interfacial compatibility between electrolyte and lithium anode. Furthermore, an ultra-thin PPC-LZO CSE with a total thickness of 22 μm was prepared and used in NCM622/CSE/Li solid-state cell, which shows an initial discharge capacity of 165.6 mAh/g at the current density of 0.5C and a remaining capacity of 113.0 mAh/g after 250 cycles at room temperature. Rise to 1C, the cell shows an initial discharge capacity of 154.2 mAh/g with a remaining capacity of 95.6 mAh/g after 250 cycles. This ultra-thin CSE is expected to be widely applied in high energy-density solid-state battery with excellent room-temperature electrochemical performances.

Poor interface stability is a crucial problem hindering the electrochemical performance of solid-state lithium batteries. In this work, a novel approach for interface stability was proposed to integrate the cathode/solid electrolyte by forming an electrolyte buffer layer on the rough surface of the cathode and coating a layer of graphite on the side of the electrolyte facing the lithium anode. This hybrid structure significantly improves the integration and the interface stability of the electrode/electrolyte. The interfacial resistance was dramatically reduced, the stability of the plating/stripping of Li metal was enhanced, and the growth of lithium dendrites was also inhibited due to the formation of the LiC6 transition layer. The obtained solid-state lithium battery shows enhanced rate performance at room temperature from 0.5 to 4 C and stable cycling performance at 1 C with a retention capacity of 100 mAh g-1 after 200 cycles. This integrated electrode/electrolyte design approach is expected to be widely used to improve interfacial stability and room-temperature electrochemical performance of solid-state batteries.

High ionic conductivity, strong stability to lithium metal, convenient preparation and good adaptability to cathodes are the important prerequisites for the practical application of solid-state electrolytes (SE). In this work, an 'environment-friendly' poly(1,3-dioxolane) (PDOL) solid electrolyte membrane was for the first-time prepared by a rapid surface-initiating 1,3-dioxolane (DOL) polymeration process under the interaction of substrate and initiator. The -SiO3, -CaO5 and -NaO3 groups on the surface of glass substrate can react with the oxygen atoms on the DOL ring, initiate the rings opening and polymerizing to be long chains under the action of LiPF6, which provides an efficient and environment-friendly preparation method for PDOL membrane without any organic solvent release, and the monomer conversion rate of the DOL reaches 97.6%. This highly polymerized PDOL electrolyte is friendly to the lithium metal environment and shows strong stability, the Li/SE/Li cell can run stably for nearly 4000 h at a current density of 0.3 mA/cm2. High electrochemical stability window up to 5.0 V enables PDOL electrolyte friendly adapt to various cathode environments including sulfur (S) and LiFePO4, and LiCoO2 and Li(Ni0.6Co0.2Mn0.2)O2 (NCM622). The assembled NCM622/SE/Li solid-state soft-pack battery can be cycled for 300 cycles at 0.5 C with the capacity retention of 85%. This PDOL electrolyte membrane shows a high promising commercial application prospect due to its friendly and high-efficiency polymerization process and strong adaptability to electrodes.