Effects of Dissolved Transition Metals on the Electrochemical Performance and SEI Growth in Lithium-Ion Batteries

Transition metal dissolution is one of the major causes of capacity and power fade in lithium-ion batteries employing transition metal oxides in the positive electrode. Accelerated testing was accomplished by introducing transition-metal salts in the electrolyte in order to study the effects of dissolution on performance. It is shown that metal dissolution causes a reduction in capacity and cycle stability in full cells. The SEI layer resistance in the negative electrode of full cells increases with increasing concentration of transition metal salts. The growth of the SEI layer is non-uniform and is believed to be caused by the reduction of transition metal species in the negative electrode leading to an increase in inorganic component of the SEI layer.