Mesocarbon Microbeads Boost the Electrochemical Performances of LiFePO4||Li4Ti5O12 through Anion Intercalation

Abstract Li‐ion batteries with LiFePO 4 cathode and Li 4 Ti 5 O 12 anode show promise for storing renewable energy. However, their low output voltage results in a low energy density. In contrast, dual‐ion batteries with graphite cathode and Li 4 Ti 5 O 12 anode can achieve a high output voltage of >3.0 V. In this study, mesocarbon microbeads (MCMB)@LiFePO 4 ||Li 4 Ti 5 O 12 dual‐ion batteries are developed to address these issues. In the cathode, MCMB improves the conductivity of LiFePO 4 and increases the output voltage by the intercalation of anions in the cell voltage range of 2.1–3.5 V. Moreover, the LiFePO 4 shell sustains the structural integrity of MCMB and generates in situ a cathode‐electrolyte interphase (CEI) with rich LiF. Owing to these unique compositional and structural features, MCMB@LiFePO 4 ||Li 4 Ti 5 O 12 manifests much better electrochemical performance than LiFePO 4 ||Li 4 Ti 5 O 12 and MCMB||Li 4 Ti 5 O 12 . It sustains 89.6 % of the initial capacity after 1200 cycles at 0.2 A g −1 and achieves a specific energy up to 128 Wh kg −1 at 179 W kg −1 .