Polypyrrole coated hollow metal–organic framework composites for lithium–sulfur batteries

Abstract

Polypyrrole coated hollow MOF composites are synthesized for Li–S battery electrodes, combining the porous structure of ZIF-67 and high conductivity of polypyrrole. The composites obtained a high initial specific capacity and good cycling performance.

Improve redox activity and cycling stability of the lithium‐sulfur batteries via in situ formation of a sponge‐like separator modification layer

“…Typically, at 0.2C, the discharge capacities from the fifth to the 35th cycle were reduced by 75.1 mAh g −1 for the cell with PE separator, which probably due to the diffusion of the soluble polysulfides to the anode side through the root‐like membrane. As verified by the previous work, the polysulfide can undergo an irreversible electrochemical reaction with the metal Li, leading to the loss of the cathode active material. The cell with KB/PE separator, another control membrane, exhibits a 19.6 mAh g −1 decrease in discharge capacities, further confirming a degradation of performance recovery capability due to the shuttle effect of polysulfides.…”

“…Unfortunately, because of the weak adsorption between the polar polysulfides and nonpolar carbon, the shuttle effect of soluble polysulfides cannot be effectively suppressed with these separators. [14][15][16] Modifying the carbon-coating layer with polysulfide anchoring materials, such as polar metal oxides [17][18][19][20][21][22][23][24] and polymers, [25][26][27][28][29] and MXene 30 can bring additional advantages and thus effectively restrain the shuttle effect of polysulfide. The trapped polysulfide on the modified carbon layer is expected to block the Li + diffusion channels.…”

Effect of Crystal Structures on Electrochemical Performance of Hierarchically Porous CoSe2 Spheres as Anodes for Sodium‐Ion Batteries

“…To explain the reason why the o‐CoSe 2 spheres have superior performance, the electrochemical redox reaction kinetics was analyzed by the CV method as reported before . Figure a showed the CVs of the o‐CoSe 2 electrode at different scanning rates of 0.2–1.0 mV s −1 .…”

“…[15] To explain the reason why the o-CoSe 2 spheres have superior performance, the electrochemical redox reaction kinetics was analyzed by the CV method as reported before. [13] Figure 6a showed the CVs of the o-CoSe 2 electrode at different scanning rates of 0.2-1.0 mV s À 1 . Strong peaks of several strong redox peaks about 1.28 V and 2.08 V are selected to calculate the corresponding b-values in the dynamic behavior of the electrode.…”

“…Herein, many mature materials for lithium-ion batteries (LIBs) may not be directly employed as anode materials for the SIBs. [5][6][7][8][9][10][11][12][13] For example, graphite, a commercial anode material for LIBs, but it displays a very low capacity of below 35 mA h g À 1 in the SIBs. [14] Moreover, above mentioned characteristics of Na + may cause a large volume expansions, poor reaction dynamics, and unsatisfied cycling performance of the electrode materials during discharge/charge process.…”