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High interface impedance, slow ion transmission, and easy growth of lithium dendrites in solid-state lithium battery are main obstacles to its development and application. Good interface combination and compatibility between electrolyte and electrodes is an important way to solve these problems. In this work, we successfully combined a high ionic conductive polymerized 1,3-dioxolane (PDOL) solid-state electrolyte and a PDOL gel-state electrolyte to form a rigid-flexible composite structural electrolyte and realized the gelation modification of solid electrolyte/electrode interface. This "PDOL SE + PDOL Gel" composite structure not only improves the electrode/electrolyte interfacial contact, reduces the interfacial impedance, but also inhibits the growth of lithium dendrites in the interface between lithium anode and electrolyte by forming an uniform Li-Zr-O and LiF composite protection layer. This composite electrolyte has high ionic conductivity of 5.96 × 10

High room-temperature ionic conductivity and mechanical property are essential for the application of solid electrolyte. In this work, a poly(vinylidene fluoride) (PVDF)-based composite polymer solid electrolyte membrane (CSE) incorporated with Li7La3Zr2O12 (LLZO) fillers and high-strength porous skeleton was prepared. The introduction of LLZO increased the ionic conductivity of PVDF at room temperature by reducing the crystallinity of PVDF matrix, and the addition of skeleton greatly improved the mechanical property of electrolyte membrane and inhibited the growth of lithium dendrites. The prepared PVDF-LLZO CSE has a room-temperature ionic conductivity of 1.75 × 10−4 S/cm, and the tensile strength reaches 95 MPa, which greatly enhanced the ability of lithium dendrite suppression. The assembled LiNi0.6Co0.2Mn0.2O2 (NCM622)/CSE/Li cell shows an initial capacity of 151 mAh/g with a retention capacity of 108 mAh/g after 100 cycles at the current density of 0.5 C. This ultrathin PVDF/LLZO CSE has a great application prospect in solid-state lithium batteries.

Electrodes with high conductivity and flexibility are crucial to the development of flexible lithium-ion batteries. In this study, three-dimensional (3D) LiFePO4 and Li4Ti5O12 fiber membrane materials were prepared through electrospinning and directly used as self-standing electrodes for lithium-ion batteries. The structure and morphology of the fibers, and the electrochemical performance of the electrodes and the full battery were characterized. The results show that the LiFePO4 and Li4Ti5O12 fiber membrane electrodes exhibit good rate and cycle performance. In particular, the all-fiber-based gel-state battery composed of LiFePO4 and Li4Ti5O12 fiber membrane electrodes can be charged/discharged for 800 cycles at 1C with a retention capacity of more than 100 mAh·g−1 and a coulombic efficiency close to 100%. The good electrochemical performance is attributed to the high electronic and ionic conductivity provided by the 3D network structure of the self-standing electrodes. This design and preparation method for all-fiber-based lithium-ion batteries provides a novel strategy for the development of high-performance flexible batteries.

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.

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.