A universal natural hydroxy propyl methyl cellulose polymer additive for modifying lignocellulose-based gel polymer electrolytes and stabilizing lithium metal anodes

Defects in gel polymer electrolytes (GPEs) limit the comprehensive performance of lithium-ion batteries (LIBs). Even using an excellent lignocellulose (LC)-based GPE is not sufficient for practical applications due to its poor mechanical properties, low liquid absorption and ionic conductivity. To eliminate these limitations, in this work, a novel biodegradable hydroxy propyl methyl cellulose (HPMC) polymer with a remarkable swelling effect was added to an LC-based polymer matrix. The LC/HPMC (LCH) membrane prepared by the phase transfer method retains the excellent performance of the LC membrane. A large amount of free volume is formed in the corresponding GPE due to the swelling effect, which can remarkably improve the physical and electrochemical properties, including the absorption of the liquid electrolyte (1168 wt%), mechanical property (14.45 MPa), ionic conductivity (6.14 × 10−3 S cm−1, 25 °C), lithium ion transfer number (tLi+ = 0.75), charge/discharge performance (162 mA h g−1 at 0.2C), and excellent regulation ability of Li deposition. Moreover, the overpotential of the Li/LCH-based GPE/Li symmetric battery is stable for more than 1000 h, which illustrates that the addition of the HPMC can provide long-term protection for lithium metal electrodes. [Display omitted] •Adding HPMC provides long-lasting protection for lithium metal electrodes.•The addition of HPMC does not weaken the advantages of LC.•The composite membrane has outstanding comprehensive performance.•HPMC is first used as an additive in LIBs.•HPMC is biodegradable.