Post-test analysis of 3ET205 module LC03TL12 from chloride motive power

摘要

ANL's analysis and Diagnostics Laboratory conducted a Simplified Federal Urban Driving Schedule (SFUDS) life evaluation on a 3ET205 lead-acid module from Chloride Motive Power in England. Like other 3ET205 modules, module LC03TL12 consisted of three cells with tubular positive electrodes as the primary design feature. Testing began with an abbreviated performance characterization of 28 cycles. The module achieved a specific energy of 34.6 Wh/kg for 3-h discharges and a 30-s peak power of 90 W/kg at 50% depth of discharge (DOD). These values were consistent with previously tested modules of this design. The characterization phase was followed by evaluation of a modified SFUDS regime to 100% DOD. The modification was a 400-A limit to prevent excessive voltage depression during the high-power steps in the SFUDS algorithm. The module maintained a net specific energy at or near 27.6 Wh/kg over the first 100 cycles and then began to decline abruptly. The end-of-life criteria, 80% of initial SFUDS energy, occurred on cycle 149. A series of constant-current discharges at this point effected a partial recovery in capacity from 85 to 92% of the initial 191 Ah at the 3-h rate. The module was returned to SFUDS cycling on cycle 162, but testing was officially terminated after 167 cycles, when the specific energy again declined below 80%. Resistance measurements made throughout the evaluation revealed an accelerating increase in internal resistance. Module LC03TL12 was then placed on float charge for two months, and following a few cycles of constant- current discharge, it was subjected to cell-level diagnostic tests. These tests formed part of a post-test analysis which also included teardown and examination of selected electrode materials.