Abstract: Lithium-sulfur (Li-S) batteries possess an ultra-high theoretical energy density of 2600 Wh·kg⁻¹, showing promise for commercial applications. However, the reaction intermediates, which are highly soluble in the electrolyte, cause the notorious “shuttle effect”, seriously deteriorating the cycling performance of Li-S batteries. In this work, by selecting the precursor anions, the micromorphology of NiCo-B is controllable regulated accompanied with enhanced adsorption towards polysulfide, which effectively inhibits the shuttle effect. The experimental results show that NiCo-B(Cl⁻) synthesized from nickel chloride and cobalt chloride has the largest specific surface area and the strongest adsorption towards polysulfide compared with the bimetallic borides taking acetate or sulfate as the precursors. Multiple electrochemical characterizations show that NiCo-B(Cl⁻) can endow the fastest reaction rate and a high discharge capacity of 1184.9 mAh·g⁻¹ at a cycling rate of 0.5C. This work provides an effective strategy for regulating the catalyst’s micromorphology and optimizing adsorption abilities towards polysulfide, offering a reference for the rational design of high-efficiency Li-S catalysts.