Suppressing the Mn dissolution in LiMn2O4 positive materials toward long-life lithium ion battery through Gd2O3 surface modification

As one of the most potential positive materials for cobalt-free lithium ion batteries, the lithium manganate cathode materials are extremely attractive because of their low-cost and low toxicity compared to other cathode materials, but they still suffer from the serious capacity fading because of the transition metal dissolution (Mn). Herein, a layer of Gd 2 O 3 coating is coated on the surface of lithium manganate by a simple wet chemical method. The Gd 2 O 3 coating can reduce the side reactions as well as Mn dissolution by suppressing the direct contact between the electrolyte and the positive electrodes. Consequently, the modified spinel LiMn 2 O 4 @Gd 2 O 3 electrode has delivered significantly improved electrochemical performance. ICP measurements demonstrate that the amount of manganese dissolved in electrolyte is effectively decreased, which is approximately one-third of the pristine sample. Thus, the LiMn 2 O 4 @Gd 2 O 3 provides higher capacity retention at both low current density (1 C) and high current density (5 C). This work reveals that the Gd 2 O 3 coating is a straightforward but effective strategy of enhancing the structural stability and inhibition of Mn dissolution of spinel Mn-based positive electrodes.