<p>Lead-acid batteries (LABs) are one of the most important energy storage systems, widely used in automotive, industrial, and backup applications. However, lead-acid batteries exhibit limitations such as relatively low energy density, limited service life, etc. The aim of improving the performance of LABs is to search for new materials with better physicochemical and electrochemical properties. One of the most important research directions is the use of various types of carbon materials as additives to electrode active masses. The presented research involved the results of the effect of the addition of a new type carbon material on the properties of the positive and negative active masses of a lead-acid battery. The carbon material was obtained by carbonization of sheep’s wool fibers. Experimental results show that the new additive improves the properties of active masses, especially during its preparation, although electrical conductivity of the carbon material is relatively low. This demonstrates that even carbon materials with moderate electrical properties can improve the efficiency of lead-acid battery production technology and its performance.</p> Graphical abstract <p></p>