Energy
storage devices that are safe to use and thermally stable
and have a wide working electrochemical window and high specific capacity
would be a boon to modern society. All-solid-state lithium-metal batteries
(ASSLMBs) are promising devices for energy storage because they fulfill
these requirements. In this study, we used a solution-casting method
to synthesize a freestanding trilayer hybrid solid-state electrolyte
(Tri-HSE) membrane from a suspension of interconnected Li6.28La3Zr2Al0.24O12 (Al-LLZO,
as the filler), poly(vinylidene fluoride)/poly(ethylene carbonate)
(PVDF/PEC, as the blended polymer), lithium bis(trifluoromethanesulfonyl)imide
(LiTFSI, as the salt), and succinonitrile (SN, as the plasticizer).
The as-prepared Tri-HSE membrane exhibited a high ionic conductivity
(ca. 3.91 × 10–4 S cm–1 at 25 °C), a high Li transference number (ca. 0.78), and a high tensile strength (ca. 11.36 MPa). The symmetric cell (Li/Tri-HSE/Li) was stable during
Li plating/stripping cycles for 470 h without any short-circuiting.
The assembled NCM811/Tri-HSE/Li full cell operated between 2.6 and
4.2 V cut-off voltages, displaying a high initial discharge capacity
(162.59 mAh g–1) and a high capacity retention (92.41%)
after 100 cycles at a rate of 0.1C. Also, at a rate of 0.2C, it displayed
admirable capacity retentions and average Coulombic efficiencies of
87.52, 83.40 and 99.21, 99.47%, after 450 and 250 cycles, at 4.2 and
4.3 V cut-off voltages, respectively. Moreover, the 5 × 3 cm2 dimensional pouch cell assembled using the same membrane
reveals an average Coulombic efficiency and capacity retention of
99.53 and 95.58% after 30 cycles, respectively. Therefore, this as-synthesized
Tri-HSE membranecharacterized by high flexibility, ionic conductivity,
mechanical strength, wide electrochemical window, and low in situ heat generationappears to be a promising
solid-state electrolyte for upcoming generations of lithium-metal
batteries operated at room temperature.
