Negative plates performance

Central Laboratory for Electrochemical Power Sources, Bulgaria, S.E.A. Tudor, Politecnico di T orino, BritejEuram Project BE97—4085, Task 3 Improvements in negative plate performance. Annual Report 1 January 1999 to 31 December 1999, Advanced Lead-Add Battery Consortium, Research Triangle Park, NC, USA, 2000. 

Demand for high performance SLI batteries has led to the development of smaller, lighter batteries that require less maintenance. The level of antimony is being decreased from the conventional 3—5% to 1.75—2.75% to minimise the detrimental effects. Lead alloys that contain no antimony have also been introduced. Hybrid batteries use a low antimony—lead alloy in the positive plate and a calcium—lead alloy in the negative plate. 

Shiomi M, Funato T, Nakamura K, Takahashi K, Tsubota M. Effects of carbon in negative plates on cycle-life performance of valve-regulated lead/acid batteries. J Power Sources 1997 64 147-152. 

The influence of barium sulfate additions on the performance of negative plates has been studied extensively [21,25]. Barium sulfate is isomorphous with lead sulfate and therefore functions as a nucleation centre ( seed ) for the precipitation of the discharge product and favourably restricts its crystal size (see Section 4.5.1, Chapter 4). Strontium sulfate behaves similarly. It has been suggested that the effectiveness of barium sulfate is directly attributable to the number of nucleii present rather than to the amount added. The optimum amount of barium sulfate when combined with other additives for use in automotive batteries has been found to be between 0.3 and 0.5wt.%. 

The eoneern over the performance of negative plates in VRLA batteries has resulted in renewed interest in the influence and mechanisms of organic additives and extensive research programmes have been carried out under the auspices of the ALABC. This work has included an assessment of 34 materials, five of which were synthetie organie compounds that were identified to have the potential to act as effective expander components in lead-acid batteries [32]. Preliminary screening tests for stability in acid, impurities and thermal stability, followed by studies of potentiostatic transients, impedance plots, and cyclic voltammograms [33], have... 

It can be seen that with increase of water content in the semi-suspension the capacity of the plates increases. The CCA performance of all batteries under test is the same, as it is limited by the negative plates. 

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