Enhancement of Lithium-Ion Transport in Poly(acrylonitrile) with Hydrogen Titanate Nanotube Fillers as Solid Polymer Electrolytes for Lithium-Ion Battery Applications

Abstract

In the present work, we report the enhancement of lithium-ion dissociation and transport in poly(acrylonitrile) host promoted by the addition of hydrogen titanate nanotube fillers for solid polymer electrolytes. We show experimental and theoretical evidence of lithium perchlorate dissociation due to the presence of the acidic hydrogen titanate nanotubes embedded in the polymer matrix. We performed confocal Raman microscopy analysis to reveal the presence of lithium perchlorate dissociation at the interface of polymer and nanotube fillers. The large affinity of perchlorate anions at the hydrogen titanate nanotube surface, as envisaged from the ab initio molecular dynamics simulations, could be responsible for the enhancement of more than 2 orders of magnitude in the lithium conductivity, reaching ∼4 × 10 −4 S•cm −1 for a certain amount of nanotube fillers addition.

Mini-Review: Mixed Ionic–Electronic Charge Carrier Localization and Transport in Hybrid Organic–Inorganic Nanomaterials

“…The increment of conducting polymer electronic charge carriers near the interphase could be discussed in view of at least two eventual scenarios: (one or passive ) the dopant stabilizes at the interphase due to strong polar or coulombic interactions with nanoparticles surface, or/and (two or active ) the nanoparticles are also good electronic acceptors, producing in both cases an enhancement on the doping of nearby polymer chains, as schematized in Figure 1C (upper panel). On the other hand, micro-Raman imaging has also been useful to evidence the enhancement of ionic-pair dissociation occurring near the interphase with inorganic nanoparticles, in agreement with the increment of ionic conductivity (Romero et al, 2016 ; Pignanelli et al, 2018 , Pignanelli et al, 2019a ). Analogously, two different scenarios could be discussed for ionic charge carriers: (one or passive ) the counter-ion (in analogy to the dopant anion) stabilizes at the interphase due to strong polar or coulombic interactions with nanoparticles surface yielding an enhancement on the ionic-pair dissociation, or/and (two or active ) the nanoparticles may also possess mobile ionic carriers at the surface (e.g., active filler) that can be injected into the polymer, as schematized in Figure 1C (lower panel).…”

“…An example on the use of Raman imaging to monitor the state of charge for a Li 1−x (Ni y Co z Al 1−y−z )O 2 cathode is shown and described briefly in Figure 1B (Nanda et al, 2011 ). In addition, the use of micro-Raman imaging technique is highly powerful to study simultaneously both compositional and microstructural features, especially for hybrid inorganic–organic materials, as the characteristic Raman signals for inorganic and organic compounds generally lie well-separated at lower (ν < 800 cm −1 ) and higher (ν > 800 cm −1 ) wavenumbers, respectively (Romero et al, 2016 ; Mombrú et al, 2017a , b , c ; Pignanelli et al, 2018 , 2019a , b ). Furthermore, although Raman spectroscopy is quite sensitive to diluted effects such as doping processes of inorganic materials, it is on the other hand, extremely sensitive to doping effects of organic materials such as conducting polymers (Furukawa, 1996 ).…”

Approaching high performancePVDF‐HFPbased solid composite electrolytes withLLTOnanorods for solid‐state lithium‐ion batteries

“…Therefore, solid-state electrolytes are considered as an excellent candidate to replace liquid electrolytes. [8][9][10][11] At present, many polymers have been studied as the matrix of solid polymer electrolytes (SPEs), such as poly(ethyleneoxide) (PEO), 12 polyacrylonitrile (PAN), 13 poly(vinylidene fluoride-co-hexafluoropropylene (PVDF-HFP), 14 poly(propylene carbonate) (PPC), 15 poly(vinylidene fluoride) (PVDF), 16 and so on. Unfortunately, there are many inherent issues for SPEs, which limit their commercial application in various aspects.…”

Hybrid Organic-Inorganic Materials and Interfaces With Mixed Ionic-Electronic Transport Properties: Advances in Experimental and Theoretical Approaches

“…Since the early nineties, it has been evidenced that the presence of inorganic nanomaterials into polymer matrices increases the ionic conductivity and improves the mechanical properties of solid polymer electrolytes ( Croce et al, 1998 ; Appetecchi et al, 1998 ; Croce et al, 2000 ; Serra Moreno et al, 2014 ). Although most of these cases involve no chemical bonding between inorganic nanomaterials and polymers, there is a vast variety of inorganic nanomaterials morphologies such as nanoparticles, nanorods and nanotubes acting as both passive and active fillers that have yielded an enhancement on the ionic conductivities ( Romero et al, 2015 ; Liu et al, 2015 ; Pignanelli et al, 2018a ; Pignanelli et al, 2018b ). The enhancement of ionic conduction due to the presence of inorganic nanostructures is mostly related to the ionic-pair dissociation of ordinary salts mediated by the interaction with the inorganic surface, thus favoring the fixation of anionic species and favoring the cationic conduction as evidenced by Raman microscopy and schematically depicted in Figure 2A ( Romero et al, 2015 ; Pignanelli et al, 2018a ; Pignanelli et al, 2018b ).…”

“…Although most of these cases involve no chemical bonding between inorganic nanomaterials and polymers, there is a vast variety of inorganic nanomaterials morphologies such as nanoparticles, nanorods and nanotubes acting as both passive and active fillers that have yielded an enhancement on the ionic conductivities ( Romero et al, 2015 ; Liu et al, 2015 ; Pignanelli et al, 2018a ; Pignanelli et al, 2018b ). The enhancement of ionic conduction due to the presence of inorganic nanostructures is mostly related to the ionic-pair dissociation of ordinary salts mediated by the interaction with the inorganic surface, thus favoring the fixation of anionic species and favoring the cationic conduction as evidenced by Raman microscopy and schematically depicted in Figure 2A ( Romero et al, 2015 ; Pignanelli et al, 2018a ; Pignanelli et al, 2018b ). There are other h OI materials involving chemical bonding between organic and inorganic oligomers that have shown an enhancement in the ionic conductivity with respect to their organic counterparts ( Saikia et al, 2012 ; Vélez et al, 2013 ; Saikia et al, 2014 ).…”