Characterisation of sample of silica for use in gel type maintenance free lead acid batteries

Silica based gel electrolyte has been used as one of the routes in the development of maintenance free lead acid batteries. Both precipitated silica samples and pyrogenic silica have been characterised in terms of their properties, namely, apparent density, particle size and size distribution, surface area, acid absorption etc. The samples show a wide variation in apparent density values, the pyrogenic samples having the lowest value. The particle size distribution of the pyrogenic sample is not as expected, probably because of the difference in the particle shape and formation of agglomerates. Acid absorption values also show a regular increase with the fineness of the silica sample. It is also found that the pyrogenic sample forms a gel suitable for battery electrolyte with sulphuric acid alone while the other samples require a gelling agent for repelling the silica particles and for catalysing the cross linking of siloxane groups. The finer the sample, the better the conductivity as well as the performance of the battery using the gel electrolyte. Temperature is also having an influence in the formation of the gel, high temperature accelerating the gel formation and low temperatures retarding the same. The keeping quality of the gel is also found to be good. Test results of a few small capacity batteries with gel electrolyte are presented and compared with those with pure sulphuric aci

Use of carbon black as a substitute for acetylene black for pasted dry cells

Acetylene black (AB) is the preferred carbon material due to its desirable properties and characteristics, especially in the case of paperlined cells where no electrolyte reservoir is present. However, in the present study it has been found that carbon black can be substituted for AB in pasted dry cells where an electrolyte reservoir is present in the form of the paste. Comparative studies (discharge behaviour) with a standard market product reveals that equivalent or even better discharge performance/life can be obtained using carbon black as a replacement but with modified and optimized composition of the black mi

Effect of Polyaniline Coating on “Shape Change” Phenomenon of Porous Zinc Electrode

Performance of porous zinc electrode in alkaline secondary battery systems suffers mainly from shape change and dendrite growth. Polyaniline coating in direct contact with porous zinc electrode was found to restrict zincate movement away from the test electrode, which otherwise may lead to a decrease in electrode surface area �shape change of the electrode� on repeated cycling. Constant current charge/discharge cycles of the blank and polyaniline-coated zinc electrodes have been carried out to assess the performance of the polymer film. It was found that a fibrous network of polyaniline coating allows OH− ions and restricts the diffusion of zincate ions

Stabilization of zinc electrodes with a conducting polymer

The reversibility of zinc anode in alkaline medium was enhanced by electrostatic deposition of a conducting polymer (polypyrrole). Electropolymerization of pyrrole onto zinc in aqueous medium using an organic acid as dopant is feasible and preferred as zinc is less corrosive in this medium. The structure of the polymer film was analyzed by FT-IR spectroscopy and scanning electron microscopy. The effect of the polypyrrole deposit on the zinc electrode was studied by cyclic voltammetry and charge–discharge cycling

Performance characteristics of SLI batteries assembled according to process

A process know - how for commercial production of lead - acid batteries of SLI type has been developed in this Institute. The batteries ranging in capacity from 60Ah to 135Ah were tested according to 1337372 - 1974 and found to pass all the tests successfully. In this paper the performance characteristics are reported and discusse

Factors affecting outcomes following pelvic exenteration for locally recurrent rectal cancer

Background: Pelvic exenteration for locally recurrent rectal cancer (LRRC) is associated with variable outcomes, with the majority of data from single-centre series. This study analysed data from an international collaboration to determine robust parameters that could inform clinical decision-making. Methods: Anonymized data on patients who had pelvic exenteration for LRRC between 2004 and 2014 were accrued from 27 specialist centres. The primary endpoint was survival. The impact of resection margin, bone resection, node status and use of neoadjuvant therapy (before exenteration) was assessed. Results: Of 1184 patients, 614 (51\ub79 per cent) had neoadjuvant therapy. A clear resection margin (R0 resection) was achieved in 55\ub74 per cent of operations. Twenty-one patients (1\ub78 per cent) died within 30 days and 380 (32\ub71 per cent) experienced a major complication. Median overall survival was 36 months following R0 resection, 27 months after R1 resection and 16 months following R2 resection (P < 0\ub7001). Patients who received neoadjuvant therapy had more postoperative complications (unadjusted odds ratio (OR) 1\ub753), readmissions (unadjusted OR 2\ub733) and radiological reinterventions (unadjusted OR 2\ub712). Three-year survival rates were 48\ub71 per cent, 33\ub79 per cent and 15 per cent respectively. Bone resection (when required) was associated with a longer median survival (36 versus 29 months; P < 0\ub7001). Node-positive patients had a shorter median overall survival than those with node-negative disease (22 versus 29 months respectively). Multivariable analysis identified margin status and bone resection as significant determinants of long-term survival. Conclusion: Negative margins and bone resection (where needed) were identified as the most important factors influencing overall survival. Neoadjuvant therapy before pelvic exenteration did not affect survival, but was associated with higher rates of readmission, complications and radiological reintervention