The Chemistry of TiS3 and NbSe3 Cathodes

Abstract

The cell discharge reactions of NbSe3 and TiS3 cathodes in nonaqueous lithium cells have been shown to involve three lithiums per MX3 . Using reaction with normaln‐normalBuLi as a model for cell discharge we show that cell discharge involves topochemical reactions in which the basic strucutre of the MX3 is maintained. Both NbSe3 and TiS3 are chain structures containing X‒X bonds. The false(X2)2− groups are reducible as well as the M4+ ion, accounting for the stoichiometry. The cell reaction is reversible for NbSe3 , but only partially reversible for TiS3 . Irreversibility in TiS3 is suggested to be due to a change in coordination geometry of Ti4+ from trigonal prismatic to octahedral.

Exploring the bottlenecks of anionic redox in Li-rich layered sulfides

“…20,21 Interestingly, unlike oxides, stable ligand-hole chemistry was well-known in sulfides, e.g., TiS3 (believed to exist as Ti 4+ S 2-(S2) 2-), Fe 2+ (S2) 2-, etc., since the pioneering works by Rouxel et al 22,23 In such materials, S exists fully or partially as dimerized S --Spairs and undergoes breaking of S-S bonds to regain the standard S 2state upon electrochemical insertion of Li. [24][25][26][27][28][29] However, Li (de)intercalation is only partly reversible in such materials besides rapid capacity fading. [30][31][32] Further studying the poly-sulfides such as TiS4 and VS4, mainly for their conversion-type mechanism leading to large capacities at low potential, researchers have noted that such compounds were also enlisting sulfur redox activity.…”

XPS investigations of TiOySz amorphous thin films used as positive electrode in lithium microbatteries

“…The cycling was carried out with a 3 AA/cm 2 current density for the thin films (corresponding to C/50 rate) and at the same rate for bulk TiS 3 . The discharge voltage cutoff for bulk TiS 3 was chosen at 1.3 V/ Li since it is close to values used in previous studies [6,7]. The curve trend is quite similar for both thin films.…”

“…It is worth noticing that lithium intercalation in bulk TiS 3 was already extensively studied in the late 1970s since it can react with up to 3 lithium ions per formula unit instead of 1 for bulk TiS 2 . These studies concluded that the intercalation reaction takes place into two steps [7,9,10]:…”

Lithium Batteries

“…Among a great variety of inorganic materials, transition-metal oxide (TMOs) as CrO 3 was investigated by Armand at Grenoble [20] and transition-metal dichalcogenides (TMDs) were studied by DiSalvo at Bell Laboratories [21], and later by researchers at EXXON [22][23][24][25]. Rechargeable lithium cells using Li-insertion compounds as positive electrodes were developed in the mid 1970s, when Winn and Steele [26,27] at Chloride Technical Ltd reported solid-solution electrode of TiS 2 with lithium and sodium as well, followed by the announcement of Exxon (USA) for its intention to commercialize the Li//TiS 2 system [28]; Bell Laboratories (USA) reported the development of lithium cells constructed with either NbSe 3 or TiS 3 [29], while transition-metal oxides such as V 2 O 5 , V 6 O 13 were investigated by Dickens in the UK [30]. Table 2.1 documents the numerous efforts toward the development of rechargeable lithium batteries using TMOs as positive electrode and Li metal as anode.…”