Addressing the interface issues of all‐solid‐state lithium batteries by ultra‐thin composite solid‐state electrolyte combined with the integrated preparation technology

Abstract The interfacial engineering in solid‐state lithium batteries (SSLBs) is attracting escalating attention due to the profoundly enhanced safety, energy density, and charging capabilities of future power storage technologies. Nonetheless, polymer/ceramic interphase compatibility, serious agglomeration of ceramic particles, and discontinuous ionic conduction at the electrode/electrolyte interface seriously limit Li + transport in SSLBs and block the application and large‐scale manufacturing. Hence, garnet Li 7 La 3 Zr 2 O 12 (LLZO) nanoparticles are introduced into the polyacrylonitrile (PAN) nanofiber to fabricate a polymer‐ceramic nanofiber‐enhanced ultrathin SSE membrane (3D LLZO‐PAN), harnessing nanofiber confinement to aggregate LLZO nanoparticles to build the continuous conduction pathway of Li + . In addition, a novel integrated electrospinning process is deliberately designed to construct tight physical contact between positive electrode/electrolyte interphases. Importantly, the synergistic effect of the PAN, polyethylene oxide (PEO), and lithium bis((trifluoromethyl)sulfonyl)azanide (LiTFSI) benefits a stable solid electrolyte interphase (SEI) layer, resulting in superior cycling performance, achieving a remarkable 1500 h cycling at 0.2 mA cm −2 in the Li|3D LLZO‐PAN|Li battery. Consequently, the integrated polymer‐ceramic nanofiber‐enhanced SSEs simultaneously achieve the balance in ultrathin thickness (16 μm), fast ion transport (2.9 × 10 −4 S cm −1 ), and superior excellent interface contact (15.6 Ω). The LiNi 0.8 Co 0.1 Mn 0.1 O 2 |3D LLZO‐PAN|Li batteries (2.7–4.3 V) can work over 200 cycles at 0.5 C. The pouch cells with practical LiNi 0.8 Co 0.1 Mn 0.1 O 2 ||Li configuration achieve an ultrahigh energy density of 345.8 Wh kg −1 and safety performance. This work provides new strategies for the manufacturing and utilization of high‐energy‐density SSLBs. image