For Li–S batteries,
the catalysis for S redox reaction is
indispensable. A lot of multifunctional sulfur electrode support materials
with have been investigated widely. However, most of these studies
were carried out at room temperature, and the interaction between
different components in the matrix is not often paid enough attention.
Here, we report a graphene supported BN nanosheet composite in which
the synergistic effect between BN and graphene greatly enhanced the
adsorption for polysulfides, thus leading to excellent performance
in a wide temperature range. When used as a host material of sulfur,
it can make the Li–S battery apply to a wide range of temperatures,
from −40 to 70 °C, delivering a high utilization of sulfur,
an excellent rate capability, and outstanding cycling life. The capacity
can stabilized at 888 mAh g–1 at 2 C after 300 cycles
with a capacity attenuation of <0.04% per cycle at 70 °C,
and the battery can deliver a capacity above 650 mAh g–1 at −40 °C.
Investigations of the Ag (I)-substituted Keggin K[HAgPWO] as a bifunctional Lewis acidic and basic catalyst are reported that explore the stabilization of LiS moieties so that reversible redox reactions in S-based electrodes would be possible. Spectroscopic investigations showed that the LiS-moieties can be strongly adsorbed on the {AgPWO} cluster, where the Ag(I) ion can act as a Lewis acid site to further enhance the adsorption of the S-moieties, and these interactions were investigated and rationalized using DFT. These results were used to construct an electrode for use in a Li-S battery with a very high S utilization of 94%, and a coulometric capacity of 1580 mAh g. This means, as a result of using the AgPOM, both a high active S content, as well as a high areal S mass loading, is achieved in the composite electrode giving a highly stable battery with cycling performance at high rates (1050 and 810 mAh g at 1C and 2C over 100 to 300 cycles, respectively).
An electron conductive matrix, or collector, facilitates electron transport in an electrochemical device. It is stationary and does not change during the entire operation once it is built. The interface of this matrix and an electrode is constructed at a 2D level at the micro‐scale, and naturally limits the breadth and depth of electrochemical reactions. Herein, the idea of an enhanced electrode coupled with a conducting molecule that can extend interfacial reactions is first introduced. With a spatialized interspace, this electrode can change the present understanding of the electrode process and opens up a new realm of electrode‐based reaction chemistry. A lithium–sulfur (Li–S) battery is used as the target for implementing the enhanced electrode owing to the complex multi‐electron reaction. Through the interaction of π–π stacking between graphite‐based carbon and iron (II) phthalocyanine (FePc), soluble FePc can be decorated on the surface of an electrode that has the capability of transporting electrons. The scanning tunneling microscope break junction characterization and density functional theory indicate that FePc has a strong molecular electronic conductivity. The reactants obtain electrons more easily from the conducting molecule than from the collector directly. As a result, the performance of the corresponding Li–S battery considerably improves.
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