Multifunctional Chitosan–rGO Network Binder for Enhancing the Cycle Stability of Li–S Batteries

Abstract

Although Li–S batteries are currently receiving great interest, due to their high energy density and the low cost of sulfur, practical applications are still inhibited by capacity fading that is caused by various undesirable processes. In this study, a new multifunctional network binder composed of chitosan and reduced graphene oxide (rGO) is introduced to enhance the capacitive performance of Li–S batteries. Chitosan is reacted with graphene oxide in aqueous solution to produce a homogenous network, which effectively enhances the redox system by entrapping lithium polysulfides, reinforces the mechanical properties, and allows electrical conductivity through the binder system. Collaborative relationship‐based chitosan–rGO network binder allows noteworthy improvement in the capacity decay of 0.016% per cycle at 1 C for 1000 cycles.

A Review of the Design of Advanced Binders for High‐Performance Batteries

“…Similarly, Lee and coworkers combined chitosan and graphene oxide to use as the multifunctional binder for improving the cycle stability of the Li-S cells. [184] When mixed with chitosan, graphene oxide can be reduced to rGO, forming a conductive and homogenous network, thus providing good mechanical strength as well as enhanced conductivity. With this, the Li-S cell using this binder can reach a capacity fade rate of as low as 0.016% at 1C rate over 1000 cycles.…”

Fast‐Charging Lithium–Sulfur Batteries Enabled via Lean Binder Content

“…Especially, the C1s spectrum at 289.0 eV and N1s spectrum at 401.2 eV showed an appearance of the NHCO group, which indicated successful amide bond formation between the chitosan and XNBR. [19,21,22] Considering the results of FT-IR analysis, the formation of network between chitosan and XNBR was clearly confirmed. Moreover, the chitosan-XNBR film was not dissolved in the aqueous acetic acid solution, which further confirmed the formation of the chitosan-XNBR network ( Figure S1, Supporting Information).…”

“…The chitosan showed characteristic absorption peaks at 1588, 1380, 1156, and 1036 cm −1 of the NH bending, CN stretching, COC stretching, and OH bending vibration, respectively. [19] The characteristic peaks of the XNBR spectrum were at 2237, 1734, and 1598 cm −1 , which are ascribed to the CN, CO, and CC stretching vibrations, respectively. [20] In the chitosan-XNBR specimen, the appearance of the strong peak at 1675 cm −1 is attributed to CO stretching vibrations of newly formed amide I bond (RCONHR′), and the peak at 1580 cm −1 attributed to the formation of amide II bond (RNHR′, NH 2 deformation, NH bending, and CN stretching) was observed in addition to every characteristic peaks of the chitosan and XNBR specimens.…”

“…These intermolecular bonds can improve the mechanical properties of the polymer film. [18,19] In the charging-discharging process, it is important to properly control the mechanical properties of the polymer binder in electrode. If the binder has high stiffness, the binder will present effective constrain on the volume changes of active materials.…”

“…Moreover, the deformation vibration of NH 2 at 1420 cm −1 was downshifted to 1412 cm −1 , which implied the formation of chitosan-XNBR network. [19,21,22] Figure 1d,e shows the X-ray photoelectron spectroscopy (XPS) profiles of the chitosan-XNBR. In the C1s spectrum, chitosan-XNBR presented CC, COH, CN, OCO, and CONH spectra.…”