@article {44564,
	title = {Structural elucidation of NASICON (Na3Al2P3O12) based glass electrolyte materials: effective influence of boron and gallium},
	journal = {RSC Advances},
	volume = {8},
	year = {2018},
	pages = {14422-14433},
	type = {Journal Article},
	abstract = {<p>Understanding the conductivity variations induced by compositional changes in sodium super ionic conducting (NASICON) glass materials is highly relevant for applications such as solid electrolytes for sodium (Na) ion batteries. In the research reported in this paper, NASICON-based NCAP glass (Na2.8Ca0.1Al2P3O12) was selected as the parent glass. The present study demonstrates the changes in the Na+ ion conductivity of NCAP bulk glass with the substitution of boron (NCABP: Na2.8Ca0.1Al2B0.5P2.7O12) and gallium (NCAGP: Na2.8Ca0.1Al2Ga0.5P2.7O12) for phosphorus and the resulting structural variations found in the glass network. For a detailed structural analysis of NCAP, NCABP and NCAGP glasses, micro-Raman and magic angle spinning-nuclear magnetic resonance (MAS-NMR) spectroscopic techniques (for 31P, 27Al, 23Na, 11B and 71Ga nuclei) were used. The Raman spectrum revealed that the NCAP glass structure is more analogous to the AlPO4 mesoporous glass structure. The 31P MAS-NMR spectrum illustrated that the NCAP glass structure consists of a high concentration of Q0 (3Al) units, followed by Q0 (2Al) units. The 27Al MAS-NMR spectrum indicates that alumina exists at five different sites, which include AlO4 units surrounded by AlO6 units, Al(OP)4, Al(OP)5, Al(OAl)6 and Al(OP)6, in the NCAP glass structure. The 31P, 27Al and 11B MAS-NMR spectra of the NCABP glass revealed the absence of B{\textendash}O{\textendash}Al linkages and the presence of B3{\textendash}O{\textendash}B4{\textendash}O{\textendash}P4 linkages which further leads to the formation of borate and borophosphate domains. The 71Ga MAS-NMR spectrum suggests that gallium cations in the NCAGP glass compete with the alumina cations and occupy four (GaO4), five (GaO5) and six (GaO6) coordinated sites. The Raman spectrum of NCAGP glass indicates that sodium cations have also been substituted by gallium cations in the NCAP glass structure. From impedance analysis, the dc conductivity of the NCAP glass (\~{}3.13 {\texttimes} 10-8 S cm-1) is slightly decreased with the substitution of gallium (\~{}2.27 {\texttimes} 10-8 S cm-1) but considerably decreased with the substitution of boron (\~{}1.46 {\texttimes} 10-8 S cm-1). The variation in the conductivity values are described based on the structural changes of NCAP glass with the substitution of gallium and boron.</p>},
	issn = {20462069},
	doi = {10.1039/C8RA01676C},
	author = {Allu, Amarnath R.},
	editor = {Balaji, Sathravada}
}
@article {47031,
	title = {Synthesis and characterization of LAGP-glass-ceramics-based composite solid polymer electrolyte for solid-state Li-ion battery application},
	journal = {Journal of Non-Crystalline Solids},
	volume = {558},
	year = {2021},
	month = {APR },
	pages = {120654},
	type = {Article},
	abstract = {<p>Solid State Electrolytes (SSEs) are the future alternatives of the present conventional liquid electrolytes in terms of safety, high temperature stability and also good electrochemical performance. Glass (G), based on Lithium Aluminium Germanium Phosphate (LAGP) was prepared and converted into glass-ceramics (GC) by optimized heating schedule. The crystalline LAGP has Na Super Ionic CONductor (NASICON) type unit cell where the lithium ions hop between two different positions providing long range ionic motion. To improve the inter electrode surface resistance and cell performance, Composite Solid Electrolyte (CSE) was prepared with poly (vinylidene fluoride-co-hexaflurophoaphate) (P(VDF-HFP)), 20wt\% LAGP, Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and 1-Ethyl-3-methylimidazolium bis-(trifluoromethylsulfonyl)-imide (EMITFSI). X-ray diffraction patterns confirm the formation of the NASICON phase in LAGP GC and the amorphous nature of the CSE. NMR studies confirm formation of the Ge/AlO6 octahedra and PO4 tetrahedra inside the crystal. 7Li NMR also confirmed two different Lithium sites in LAGP crystal. The ionic conductivity values of CSE and LAGP GC are (4.49 +/- 0.31) x 10(-3)Scm(-1) and (2.70 +/- 0.04) x 10(-4)Scm(-1), respectively. The thermal stability of the prepared CSE is tested upto 315 degrees C without any degradation. Two cells (Cell-I \&amp; Cell-II) were fabricated using the LAGP GC and CSE respectively. Cell-II shows the specific discharge capacity of 151mAhg1 at 50th cycle which is higher as compared to Cell-I (129mAhg(-1)) when tested at the C-rate of 0.05 degrees C.</p>
},
	keywords = {Lithium germanium phosphate, NASICON, Solid state electrolyte, Solid state NMR},
	issn = {0022-3093},
	doi = {10.1016/j.jnoncrysol.2021.120654},
	author = {Das, Anurup and Goswami, Madhumita and Illath, Kavya and Ajithkumar, T. G. and Arya, A. and Krishnan, M.}
}
