Mitigating intergranular attack and growth in lead-acid battery electrodes for extended cycle and operating life

Abstract

Deterioration in the performance of lead acid batteries is primarily governed by weight loss and growth of the positive electrodes, arising from creep and intergranular corrosion/cracking. The present investigation examines the impact of increasing the frequency of grain boundaries having low-⌺ misorientations (⌺ ≤ 29), described by the Coincident Site Lattice (CSL) model, which are known to be resistant to these intergranular degradation phenomena. Electrode microstructures of various PbCaSn alloys processed to contain frequencies of special boundaries (in excess of 50 pct) exhibited reductions in weight loss of between 26 and 46 pct accompanied by declines in grid growth of between 41 and 72 pct. Moreover, the distribution of intergranular attack/cracking in the microstructure of these alloys can be predicted on the basis of the frequency of low-⌺ special boundaries and grain size. In general, improvements in corrosion and creep/cracking occur without compromising tensile properties such as yield strength, ultimate tensile strength (UTS), and ductility. Modifying the crystallographic structure of grain boundaries in Pb alloy battery electrodes, thus, provides an opportunity for minimizing grid thicknesses (weight) and, hence, material costs in battery production, or for maximizing energy densities (Wh/kg) and cycle life performance.

Texture mediated grain boundary network design in two dimensions

“…[16][17][18][19] However, materials amenable to this thermomechanical processing strategy are mostly limited to those that readily form annealing twins and exhibit appreciable plasticity. Furthermore, even for this class of materials, successful processing recipes have been developed through empirical iteration.…”

Influence of Processing Method on the Grain Boundary Character Distribution and Network Connectivity

“…Since that time, such manipulations have become known as grain boundary engineering. Grain boundary engineering has been demonstrated to be a viable means of improving certain properties of low to medium stacking fault energy FCC materials such as austenitic stainless and microalloyed steels [2,3], nickel and nickel-based alloys [2,[4][5][6][7][8][9][10][11][12][13][14][15], and lead alloys [16][17][18]. The susceptible properties are typically grain boundary controlled, such as corrosion and stress corrosion cracking [2,[4][5][6][7][8][9][10][11][12][13][14][15][16][17][18], creep and cavitation [19][20][21][22], and weldability [23].…”

“…With automated EBSD hardware and software, it is now possible to acquire approximately 10,000 data points per hour, thus allowing characterization of a statistically significant number of grain boundaries in a reasonable time frame. Additional factors contributing to the recent advances in grain boundary engineering are reports by Palumbo et al [2][3][4][5][6][7][8][9][10][11][12][13][16][17][18] of the optimization of the GBCD through practical thermomechanical processing schedules and the recognition that improvements in the special fraction can play a crucial role in controlling the properties. A demonstration that boundary properties depend on misorientation has been presented in these proceedings by Bedrossian et al [29] who have studied the susceptibility of individual grain boundaries to corrosion by coupling automated EBSD with atomic force microscopy (AFM).…”

“…This sequential processing is effective in producing a fine grain size, reducing texture, and increasing the special fraction. Palumbo et al have reported significant improvements in properties including corrosion resistance, stress corrosion cracking, weldability, creep, and total elongation to failure [2][3][4][5][6][7][8][9][10][11][12][13][16][17][18]. The present authors have studied strain-recrystallization in oxygen-free electronic (ofe) Cu and several Ni-based alloys.…”

“…The thermomechanical processing sequences generally involve large deformation steps; with a minimum number of anneals to reduce the length of time, and thus overall cost of the forming process. Although this practice has been successful in producing quality products at affordable cost, recent work of Palumbo et al [2][3][4][5][6][7][8][9][10][11][12][13][16][17][18] indicates that significant improvements in many properties are possible with modifications to the processing schedules. This investigation focuses on evaluating the influence of processing method and annealing temperature on the resultant GBCD and connectivity of the random grain boundary network.…”