Structural Features of LiPON Glasses Determined by 1D and 2D ³¹P MAS NMR

Abstract

The relationships between structure and electrical properties of nitrided lithium phosphate glasses (LiPON) used as electrolytes for lithium batteries are key issues for better understanding and design of these materials. For the first time, the effect of nitrogen introduction in the structure of lithium phosphorus oxynitride glasses, formulated over a wide range of composition 38-55 mol.% of Li 2 O, has been studied through 31 P 1D/2D MAS NMR experiments. Information obtained from 2D 31 P/ 31 P correlation maps has been used to deconvolute the 1D 31 P NMR spectra and allowed establishing the percentage of oxide phosphate groups (PO 4 ) and phosphorus species with nitrogen (P(O,N) 4 ) as well as the connectivity scheme of the phosphate network. Finally, it has been demonstrated that the lithium content affects the structural changes induced by the introduction of nitrogen. In particular, the lower the lithium content is, the lower the total percentage of nitrided P(O,N) 4 species is. *fmunoz@icv.csic.es

NMR Spectroscopy in Glass Science: A Review of the Elements

“…These phosphorus sulfide groups are sensitive to glass composition and exhibit concentrations that depend on the amount of Ga 2 S 3 , which associates with PS 4 tetrahedra to form symmetric GaPS 4 -type environments, similar to the AlPO 4 - and BPO 4 -like associated polyhedra in oxide glasses [38,39]. Phosphorus speciation in oxyfluorides or oxynitride glasses is also known from NMR study and, for the latter materials, used to ascertain the extent of bonding between phosphorus and nitrogen [40]. Overall, 31 P NMR in glass science is relatively simple.…”

LiPON and NaPON glasses: A study of the ammonolysis of lithium and sodium metaphosphate melts

“…In fact, the nitrogen atoms can enter the glass network as di‐coordinated (=N–), and tricoordinated (>N–) nitrogen . The role of divalent and trivalent nitrogen on oxynitride glass structure has been discussed by several authors; however, the mechanisms are not yet completely understood and it has being also, recently, investigated in nitrided thin films …”

“…Nitridation of phosphate glasses was first observed by Marchand in 1983 by reaction of ammonia with polyphosphates (MPO 3 ) n ( M = Li, Na, K) at 700°C by a process called ammonolysis . Over 35 years has passed since the phosphorous oxynitride glasses were discovered, and nitrogen incorporation continues to be an active area of research due to its beneficial effects on material properties . Ammonolysis is carried out by a gradual replacement of oxygen by nitrogen involving a mixed reaction/diffusion rate‐limiting mechanism caused in the network structure .…”

“…Ammonolysis is carried out by a gradual replacement of oxygen by nitrogen involving a mixed reaction/diffusion rate‐limiting mechanism caused in the network structure . The most studied parameters to control the nitrogen incorporation in phosphate glasses are temperature, time, and ammonia flow . However, some relevant parameters that may influence the nitrogen uptake were not well defined such as the initial mass of the base glass and if the material is in powder or bulk form, among others.…”

Structural impact of nitrogen incorporation on properties of alkali germanophosphate glasses

“…Moreover, the substitution gives rise to altered configurations of the fundamental phosphate (PO 4 ) building units, converting them into cross‐linking phosphonitride‐type tetrahedra, i.e., PO 3 N and PO 2 N 2 . Most studies of phosphorus oxynitride glasses have been done on the metaphosphate composition (i.e., ratios of M 2 O/P 2 O 5 = 1 and O/P = 3), with less focus on ultra‐ or polyphosphate compositional ranges . The metaphosphate structure is characterized by PO 4 structural units with 2 BOs and 2 NBOs, i.e., Q 2 (P)‐type interconnected tetrahedra.…”