During the past decade, there has been a significant interest to use Co3O4 as an alternate anode material for lithium-ion batteries (LIB) due to its remarkably high theoretical capacity of 890 mAh g-1. The charge/discharge reaction of Co3O4 in LIB is found to be very reversible, however, a hysteresis of &gt;1.0 V vs. Li/Li+ is still a major issue that limits the usage of Co3O4 in a practical battery device. In this work, we first reveal the detailed charging mechanism of Co3O4 by combining first principle calculations with a derivative structure enumerating algorithm and ab initio molecular dynamic simulations. While the ground-state, equilibrium lithiation voltage of Co3O4 shows a large discrepancy compared to the experimental voltages, our calculated reaction pathway involving metastable phases of LixCo3O4 (x = 1, 2.5, 3, 4, 5, and 8) predicts a voltage profile in a much better agreement with experimental observations. By further examining the energetics of the metastable phases, we are also able to explain the large voltage hysteresis occurring during cycling of Co3O4 anode materials. Rearrangement of the close contact between Co and the surrounding lithia (Li2O) at the atomic scale and the facile Co-Li migration in the final Li8Co3O4 phase enable fast Co+O recombination and de-lithiation that can ultimately explain the good reversibility of Co3O4 in LIB during cycling.

Revealing the conversion mechanism of Co3O4 during lithiation from first principles calculations

253rd National Meeting (2017)

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