Insertion of lithium into the jarosite hydroxysulfate NaFe3­(SO4)2(OH)6 leads to an amorphous phase Li2+x NaFe3­(SO4)2(OH)6 (with 0 < x<0.5), through a biphasic mechanism. The latter phase exhibits reversible electrochemical lithium intercalation/deintercalation through a solid-solution-like process, leading back to the oxidized jarosite Li x NaFe3­(SO4)2(OH)6 (with 0.3 < x < 0.6), with redox cycling at 2.82 V and a capacity of 110 mAh/g at C/20. This unique topotactic reaction between an amorphous and a well-crystallized phase is interpreted on the basis of the formation of an inorganic polymer.

A cross-linked polymer ''gel'' electrolyte obtained from free radical polymerization of a vinyl monomer (acrylonitrile; AN) in a room temperature ionic liquid electrolyte (N,N-methyl butyl pyrrolidinium-bis (trifluoromethanesulphonyl)imide-lithium bis(trifluoromethanesulphonyl)imide; LiTFSI-[Py 1,4 -TFSI]) for application in high rate capability rechargeable lithium-ion batteries is discussed here. This is a novel alternative compared to the often employed approach of using a molecular liquid as the medium for performing the polymerization reaction. The polymer ''gel'' electrolytes (AN:Py 1,4 -TFSI ¼ 0.16-0.18, w/w) showed remarkable compliable mechanical strength and higher thermal stability compared to LiTFSI-[Py 1,4 -TFSI]. Despite two orders increase in magnitude of viscosity of polymer ''gels'', the room temperature ionic conductivity of the ''gels'' (1.1 Â 10 À3 -1.7 Â 10 À3 U À1 cm À1 ) were nearly identical to that of the ionic liquid (1.8 Â 10 À3 U À1 cm À1 ). The present ''gel'' electrolytes did not exhibit any ageing effects on ionic conductivity similar to the conventional polymer gel electrolytes (e.g. high molecular weight polymer + salt + high dielectric constant molecular solvent). The disorder (ionic liquid) to a relative order (cross-linked polymer electrolyte) transformation does not at all influence the concentration of conducting species. The polymer framework is still able to provide efficient pathways for fast ion transport. Unlike the ionic liquid which is impossible to assemble without a conventional separator in a cell, the polymer ''gel'' electrolyte could be conveniently assembled without a separator in a Li|lithium iron phosphate (LiFePO 4 ) cell. Compared to the ionic liquid, the ''gel'' electrolyte showed exceptional cyclability and rate capability (current density: 35-760 mA g À1 with LiFePO 4 electronically wired with carbon (amorphous or multiwalled nanotube [MWCNT]).

Two new anionic inorganic−organic hybrid compounds [H 3 O][Mn 3 (μ 3 -OH)(C 14 H 8 O 6 S) 3 (H 2 O)](DMF) 5 , I, and [H 3 O] 2 [Mn 7 (μ 3 -OH) 4 (C 14 H 8 O 6 S) 6 (H 2 O) 4 ](H 2 O) 2 (DMF) 8 , II, have been prepared by employing mild solvothermal methods. Both the compounds have three-dimensionally extended structures formed by Mn 6 and Mn 7 clusters, respectively. The connectivity between Mn 6 and Mn 7 clusters and 4,4′-sulfonyldibenzoic acid anions (SDBA 2− ) results in a six connected pcu network in I and an eight connected bcu network in II. The presence of hydronium ion (H 3 O + ) along with the solvent molecules in the channels of both the compounds suggested proton conduction in the solids. Proton conductivity studies gave values of ∼3 × 10 −4 Ω −1 cm −1 98% relative humidity in both the compounds. The high activation energies indicate a vehicle mechanism in the compounds I and II. Magnetic studies indicate antiferromagnetic behavior in both the compounds.