In my talk, I would present advances in fabrication of the solid electrolyte-based flexible li-ion fiber batteries, as well as their numerous potential applications in compliant energy storage and wearable devices. In particular, I would detail fabrication of the fiber-shaped lithium ion batteries assembled by twisting a cathode filament together with an anode filament. The cathode filament is fabricated by depositing a LiFePO₄ (LFP)-composite layer onto a steel-filled polyester conductive thread (SPCT). As anode filaments, we propose several scenarios including a Li₄Ti₅O₁₂ (LTO)-composite coated SPCT (dip-and-dry deposition), a tin-coated SPCT (PVD deposition) as well as a bare tin wire. An electrolyte composite layer consisting of LiPF₆ and polyethylene oxide is then deposited onto both the anode and cathode filament before the battery assembly. To characterize the electrochemical and mechanical properties of the proposed batteries, we performed charge-discharge tests with different C-rates, electrical impedance tests and mechanical bending tests. The fabrication of the proposed LIBs is simple and cost-effective, as compared to the fiber-shaped LIBs using carbon nanotube fibers. Moreover, the reported LIBs are well suitable for the wearable applications as they feature all-solid electrodes and electrolyte, unlike the majority of other currently existing LIBs that utilize liquid organic solution-based electrolytes that may cause leakage and cause safety concerns. Among other advantages of the proposed LIB are light weight, ease of fabrication, high specific capacitance, high energy density, and good durability.