Fabricating robust succinonitrile-based plastic crystal electrolyte (PCE) membranes with abundant and sustainable polymer skeleton and reinforcing the stability of the PCE-lithium anode interface are essential for adopting PCE in allsolid-state lithium metal batteries (ASSLMBs). Herein, renewable and low-cost cellulose is utilized as the mechanical support framework to prepare the selfstanding cellulose-based PCE (C-PCE) through the facile tape-casting method. The cellulose matrix provides excellent robustness to the hybrid C-PCE system. The fabricated C-PCE shows an ionic conductivity of about 2.1 Â 10 À4 S cm À1 and a tensile strength of over 0.5 MPa at room temperature. Solid-state lithium batteries assembled with the Li 4 Ti 5 O 12 cathode, lithium metal anode, and the prepared electrolyte films exhibit an initial capacity surpassing 155 mAh g À1 at 0.2 C and room temperature. This work presents a new attempt to use low-cost cellulose and common additives to prepare high-performance PCE membranes for lithium-battery applications.
Solid polymer electrolytes (SPEs)
are flexible, low cost, and easily
scalable for battery manufacturing. These merits make SPEs one of
the most practical solid-state electrolytes. Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), which has good mechanical
properties and good thermal stability, is considered a promising polymer
for SPEs. However, PVDF-HFP is unstable due to the dehydrofluorination
side reaction when PVDF-HFP-based electrolytes cycle with Li metal.
This reaction leads to the deterioration of the electrolyte–electrode
interface. In this work, the PVDF-HFP polymer electrolyte is modified
with LiOH during the synthesis of SPEs (pre-dehydrofluorination).
The modified electrolyte delivers significantly enhanced stability
toward the Li metal anode. The electrochemical stable window is extended
from 4.75 to 5.00 V, and the stable cycle time of the galvanostatic
test of Li symmetric cells at 0.1 mA cm–2 increases
from about 100 h to over 500 h. Ex situ scanning electron microscopy
(SEM) and X-ray photoelectron spectroscopy (XPS) analyses indicate
that the polymer degradation is suppressed after modification, and
a stable interface containing more LiF and inorganic sulfur compounds
forms between the electrolyte and Li metal; the interface could effectively
suppress Li dendrite growth. Combining electrochemical results with
ex situ SEM and XPS analysis, it is observed that the pre-dehydrofluorination
is the reason for inhibiting polymer degradation and suppressing Li
dendrite growth toward the Li metal anode. These findings will promote
the development of safe all-solid-state Li metal batteries.
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