Addressing first cycle irreversible capacity in lithium-rich layered oxides by blending with delithiated active materials

Abstract

Lithium-rich oxides (LRO), derived from NMC-type materials, are among the most promising next-generation positive electrode candidates for lithium-ion batteries. Despite their potential, their practical application is hinderend byinherently low first-cycle coulombic efficency, caused by the irreversible loss of lithium during the initial cycle. In this work, we address this drawback by chemically delithiating secondary active materials –LiMn2O4 (LMO) or LiFePO4- and subsequentyly blending them with the cobalt-free lithium rich oxide Li₁,₁₅Ni₀,₃Mn₀,₅₅O₂. The incorporation of these delithiated components improves first-cycle efficiency, with the degree of enhancement proportional to the fraction of added material, and capacity retention, while only modestly reducing overall capacity. Differential scanning calorimetry (DSC) further reveals improved thermal stability for LRO:FePO4 blends evidenced by a higher decomposition temperature and lower overall heat released. In contrast, LRO:λ-MnO2 blends show increased moisture sensitivity. Operando synchrotron X-ray diffraction confirms that the secondary active material actively participates in the electrochemical processes of the blends. Our findings demonstrate a simple, industry-compatible strategy to mitigate one of the major drawbacks of LROs, paving the way for more sustainable and high performance lithium-ion batteries