Suppressing voltage fading and improving cycling stability of Li-rich Mn-based materials by introducing MgSO4

Abstract

Li-rich Mn-based materials, as high-energy-density and low-cost cathode materials for Li-ion batteries, suffer severe irreversible voltage fading and capacity loss during cycling, associated with the instability of crystal structure at high voltage, which greatly reduces the specific energy density after cycling and thus impedes their commercialization. Here, we introduce a new strategy to mitigate voltage fading and improve the cycling performance of Li-rich Mn-based cathode materials by simply introducing MgSO₄ in the cathode during its preparation process. The results show that cycling stability and voltage fading of corresponding batteries were dramatically improved due to the high Li⁺ retention at the initial charge process and the stable cathode electrolyte interface (CEI) layer. After 100 cycles at 1C, the average discharge voltage decay is only 0.115 V (1.15 mV per cycle), with a high voltage retention of 96.7%, and the capacity remains at 91.5% after 300 cycles at 1C.