Improved activity of LMNO cathodes through strategic substitution with recycled battery waste metals

Abstract

High-voltage spinel LiMn1.5Ni0.5O4 (LMNO) is a promising cathode material for next-generation lithium-ion batteries (LIBs). However, its practical application is often limited by capacity loss and poor cycling stability due to Mn dissolution. This study presents a sustainable synthesis route for LMNO materials using Recycled Manganese Oxide (R-MO) derived from spent alkaline and Zn/C batteries. The R-MO precursor contains a significant amount of Zn (estimated 30% Zn/Mn ratio), which is incorporated into the LMNO structure, primarily occupying Li sites. The impact of varying the proportions of R-MO and MnO2 on the electrochemical performance of the LMNO materials was evaluated. While LMNO shows the highest initial capacity (121 mAh g-1), its cycling stability is poor, with only 10.58% capacity retention after 200 cycles. In contrast, the inclusion of an optimal amount of R-MO, replacing 20% of the commercial MnO2, dramatically improves the structural stability and electrochemical reversibility. This LMNO material delivers a discharge capacity of 93 mAh g-1 and exhibits exceptional long-term stability, retaining approximately 86% of its capacity after 200 cycles. These findings highlight the potential of utilizing typically detrimental battery waste contaminants, such as Zn, as beneficial dopants for high-performance LIB materials, thereby aligning the development of high-voltage cathodes with circular economy principles.