K2CsSb is an attractive photocathode for high current applications. With a quantum efficiency of >4% at 532 nm and >10% at 355 nm, it is the only cathode to have demonstrated an average current of 35 mA in an accelerator environment. We describe ongoing cathode development work for the energy recovery linac being constructed at BNL. Several cathodes have been created on both copper and stainless steel substrates, and their spatial uniformity and spectral response have been characterized. Preliminary lifetime measurements have been performed at high average current densities (>1 mA/mm2).