Improving Electrochemical Performance and Safety of Lithium–Sulfur Batteries by a “Bulletproof Vest”

Abstract

In the field of high-density energy storage, lithium–sulfur (Li–S) batteries have attracted more and more attention because of their high specific capacity and affordable cost. However, their actual implementation is hindered by the dissolution of polysulfides and severe safety concerns caused by flammable electrolytes. Herein, we report the preparation of an interlayer that can effectively suppress polysulfide shuttling and increase the working temperature range. In this work, polyamide nanofibers (ANFs) are used as the substrate material to prepare the Ni­(OH)2@ANFs-Ni (NAFN) film that works as the interlayer on the “outside” of the cathode in situ. The experimental results show that Li–S batteries containing NAFN as the interlayer can achieve excellent outstanding stability in a long cycle life. After 800 cycles at 1 C, the capacity remains at 482 mA h/g, with a decay rate of 0.047%. At high temperature (60 °C), after 500 cycles at 1 C, its capacity is 622 mA h/g with a decay rate of 0.079%. Therefore, the flexible design of the NAFN interlayer provides the growth of high-performance Li–S batteries with novel insights. The ultrathin, microporous structure of the interlayer tightly wraps the cathode material, just like the addition of a “bulletproof vest” inside the Li–S batteries. The plentiful amide functional groups of the “bulletproof vest” enable the strong complexation reaction with polysulfides to suppress the polysulfides’ shuttling effect and ensure a facile Li+ transfer. At the same time, the nickel hydroxide is able to accelerate the redox kinetics via reaction with polysulfides to produce the intermediate thiosulfate groups. Also, the ANFs as the heat-resistant material ensure the stability of the batteries at high temperatures.

Optimizing conditions and improved electrochemical performance of layered LiNi1/3Co1/3Mn1/3O2 cathode material for Li-ion batteries

“…The observed low capacity and fading with cycle number may be due to poor crystallinity as indicated by appearance of broad peaks in XRD patterns as compared to sample heated at high temperature. The irreversible capacity loss due to poor crystalline nature of compound has been observed in previous studies [37][38][39]. The SEM image clearly shows absence of crystallinity (Fig.…”

“…Finally, electrochemical impedance spectroscopy (EIS) was performed to understand rate performances and estimate kinetic process on the LiNi 1/3 Co 1/3 Mn 1/3 O 2 cathode materials obtained in different methods [39][40][41][42][43]. Figure 11a compares Nyquist plots (Z′ vs. Z″) of different NCM111 electrodes, prepared from the direct solid state reaction and mixed hydroxide approaches.…”

“…The semicircle in the medium frequency region corresponds to the charge transfer resistance (R ct ) and interfacial resistance (R if ) between electrode and electrolyte [46,47]. The inclined (sloping) line along Z″ in the low frequency region is the Warburg impedance (Z W ), due to solid state diffusion of Li + ions into an active material during charge-discharge [39]. In comparison, among three electrodes, the MH-900-8 h and MH-950-8 h have shown smaller diameter of the semicircle, indicating low charge transfer resistance and interfacial resistance, which result in stable and better diffusion of Li ions at interface.…”

Carbon Nanotube-Modified Nickel Hydroxide as Cathode Materials for High-Performance Li-S Batteries

“…The introduction of porous CNT as a support material for LiPSs, not only improves the 3D conductive network structure, but also facilitates the electron transportation, resulting in high-rate capabilities [ 30 ]. Therefore, it is very promising to design a composite that decorates carbon nanotubes on nickel hydroxide nanosheets [ 31 , 32 ]. It can combine the advantages and alleviate the disadvantages of the two components [ 33 , 34 ].…”

Multifactorial engineering of biomimetic membranes for batteries with multiple high-performance parameters

“…ANF-based composites have been utilized as electrode materials 35,36 and separators [37][38][39] in various energy storage systems 40,41 including lithium sulfur batteries 42 due to their high mechanical and thermal properties, similarly, np-ANF membranes also display a high Young's modulus of E = 9.2 ± 0.5 GPa (55 times higher than Celgard TM 2400) and high thermal resistance (600 °C). These properties make possible simultaneous suppression of lithium dendrites extending the life cycle of the Li-S batteries to 3500+ cycles at 3C.…”