Lithium-Ion

Simple Voltage Control Method to Enhance LMR Lifetime Li- and Mn-rich layered cathodes such as 0.5LiNi1/3Mn1/3Co1/3O2• 0.5Li2MnO3 may deliver initial capacities exceeding 250 mAh/g, due to the participation of anionic oxygen redox from the Li2MnO3 phase at voltages above 4.5 V. While operation above 4.5 V induces lattice oxygen release and accelerated voltage fade, improved voltage stability is only achieved at the cost of reduced accessible capacity. Below 4.5 V, there is a sloping voltage profile associated with Ni2/4 and Co3/4 oxidation, while above that voltage there is a plateau from irreversible Li2MnO3 activation and lattice oxygen release. Similarly, voltages below 3 V leads to irreversible Mn3/4 redox. As a result, the wide 24.8 V window simultaneously triggers Mn oxidation and O2(g) formation, leading to the most severe voltage decay, while narrow windows such as 34.8V and 24.5 V significantly mitigate degradation pathways at the expense of accessible capacity. Limiting the upper cutoff voltage to 4.5 V also allows for a gradual activation of the Li2MnO3 phase, fully accessing that capacity after about 20 cycles.

0.1C rate 24.8V

Voltage window tuning of Li- and Mn- rich layered cathode enables controlled access to Mn and O redox, mitigating cation migration and oxygen release. Even under a restricted window 4.5 V, Li2MnO3 activates gradually with successive cycles, optimizing voltage stability and accessed capacity. Source: 1 A. Abdel-Ghany et al 2025. 2 M. Yuan et al 2024.

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