Polymer-based solid-state electrolytes are shown to be highly promising for realizing low-cost, high-capacity, and safe Li batteries. One major challenge for polymer solid-state batteries is the relatively high operating temperature (60-80°C), which means operating such batteries will require significant ramp up time due to heating. On the other hand, as polymer electrolytes are poor thermal conductors, thermal variation across the polymer electrolyte can lead to nonuniformity in ionic conductivity. This can be highly detrimental to lithium deposition and may result in dendrite formation. Here, a polyethylene oxide-based electrolyte with improved thermal responses is developed by incorporating 2D boron nitride (BN) nanoflakes. The results show that the BN additive also enhances ionic and mechanical properties of the electrolyte. More uniform Li stripping/deposition and reversible cathode reactions are achieved, which in turn enable all-solid-state lithium-sulfur cells with superior performances.
An
all-solid-state lithium–sulfur battery (ASSLSB) is a
promising candidate for post-Li-ion battery technologies with high
energy densities and good safety performance. However, the intrinsic
insulating nature of sulfur requires triple-phase contact with an
ionic conductor and an electronic conductor for electrochemical reactions,
which decreases the amount of active surface and lowers the charge-transfer
efficiency. In this work, a double-phase interface constructed from
a mixed ionic/electronic conductor is proposed to enhance the solid-state
electrochemical reaction of sulfur. By employing lithium lanthanum
titanium oxide/carbon (LLTO/C) nanofibers with mixed ionic/electronic
conductivity, enhanced charge-transfer behavior is realized at the
sulfur–LLTO/C double-phase interface, compared to the traditional
triple-phase interface. As a result, high sulfur utilization and excellent
rate performance are achieved. And the facilitated charge transfer
shows great potential to lower the operating temperature and improve
the sulfur content for practical applications of ASSLSBs. Cycle performance
is also enhanced due to the suppressed shuttle effect of polysulfides
by the incorporation of the LLTO/C nanofibers.
The
sluggish conversion reaction of sulfur and poor interfacial
contact restrict electrochemical performance and practical application
of all-solid-state Li–S batteries. Herein, we present a rational
design of cell structure with a cathode-supported-electrolyte configuration
to attain high-performance all-solid-state Li–S batteries.
A mechanically robust sulfur cathode was constructed, and a slurry-based
polymer electrolyte layer was subsequently cast on the cathode to
form an intimate interfacial contact. The resulting battery shows
a high specific capacity and good cycle performance. As a proof-of-concept,
full cells with variable configurations, excellent flexibility, and
safety features are demonstrated.
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