Dual-ion batteries (DIBs) inherently suffer from limited energy density. Proposed here is a strategy to effectively tackle this issue by employing locally ordered graphitized carbon (LOGC) cathodes. Quantum mechanical modeling suggests that strong anion-anion repulsions and severe expansion at the deep-charging stage raise the anion intercalation voltage, therefore only part of the theoretical anion storage sites in graphite is accessible. The LOGC interconnected with disordered carbon is predicted to weaken the interlaminar van der Waals interactions, while disordered carbons not only interconnect the dispersed nanographite but also partially buffer severe anion-anion repulsion and offer extra capacitive anion storage sites. As a proof-of-concept, ketjen black (KB) with LOGC was used as a model cathode for a potassium-based DIB (KDIB). The KDIB delivers an unprecedentedly high specific capacity of 232 mAh g-1 at 50 mA g-1 , a good rate capability of 110 mAh g-1 at 2000 mA g-1 , and excellent cycling stability of 1000 cycles without obvious capacity fading.
Keywords: anions; dual-ion batteries; graphite; intercalations; ketjen black.
© 2020 Wiley-VCH GmbH.