LABD team has been conducting investigations aimed at improving the power output and charge acceptance of tubular plates through a novel plate design and thus make them suitable for electric vehicle and photovoltaic battery applications.
Strap grid tubular positive plates (SGTP). By enclosing PAM in separator tubes, breathing and shedding off of the active mass was restricted. The conventional tubular plate design of positive battery plates has some disadvantages: (i) thick plates – 8 mm, (ii) low charge acceptance, (iii) low power, (iV) high g coefficient. In an attempt to overcome these shortcomings the shape of the tubes has been changed from cylindrical to flattened elliptic and the current collector spines have been replaced with strap grids.
This new plate design has the fallowing advantages: (i) thin plates – 3.5 mm, (ii) 1 mm PAM thickness, (iii) low polarization on discharge, (iv) high charge acceptance, (v) low g coefficient. Tubular plates of the novel design have capacity and power performance similar to that of pasted plates and cycle life close to that of tubular batteries. These improved characteristics make SGTPlates suitable for HEV and PV applications.
Mechanism of the process of residual sulphation in the interior of the positive plates. During charge, H2SO4 concentration increases in the inner plate parts close to the strap. In the pores of Active Mass Current Collecting Layer (AMCL), H2SO4 concentration is high and the solubility of PbSO4 crystals is low. Parts of PbSO4 crystals remain unoxidazed in the PAM of charged plates. Consequently, the capacity of the plate is low. The processes that take place in AMCL during specific battery operation have been elucidated at LABD.
Applications of batteries with SGTP. Investigations performed so far have shown that SGTP batteries can endure 5,500 electric vehicle cycles (55,000 km) when tested according to the ECE-HEV cycling test protocol. It has been established that photovoltaic SGTP have cycle life longer than eight gross cycles corresponding to more 8,800 h of cycling.
Keywords: strap grid tubular plates, SGTP design, charge acceptance, HEV applications of LAB, PV applications of LAB, active mass current collecting layer
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