Organic cation (DMPI) intercalated graphite anode for high voltage next generation dual-ion batteries

Abstract

Developing advanced energy storage systems to address the intermittency of renewable energy sources is crucial for meeting ever-increasing energy demands. Among post lithium-ion battery systems, dual-ion batteries (DIBs) have shown bright prospects in developing low-cost and safe batteries with good electrochemical performance. Herein we have modelled, for the first time, organic cation intercalated graphite systems. Imidazolium based ionic liquid 2,3-dimethyl-1-propyl imidazolium chloride (DMPI-Cl) with the AlCl₃ salt has been implemented as an electrolyte. Using first principles calculations, we have performed DMPI cation intercalation into the graphite anode based on different plausible staging mechanisms. The intercalation energy characteristics indicate favourable intercalation of DMPI into graphite following the staging mechanism, which has been further confirmed by a simulated X-ray diffraction study. A higher cell voltage (3.7–4.6 V range) comparable to lithium-ion batteries along with a maximum capacity of 62 mA h g⁻¹ has been achieved. Charge transfer analysis presents +0.87 |e| charge transfer from DMPI to graphite, indicating DMPI cation intercalation into graphite during the charging process. Moreover, the metallic character of the DMPI cation intercalated graphite system and diffusion barrier as low as 0.2 eV suggest a constant electronic conductivity and better rate performance, respectively. Furthermore, we have explained the reason behind the inapplicability of the 1-ethyl-3-methyl imidazolium (EMI) cation as an organic cation for dual-graphite batteries and hence highlight the need to explore alternative ionic liquids. These results provide clear understanding of DMPI cation intercalation into graphite anodes and could be helpful in fabricating dual graphite electrode-based DIBs with better electrochemical performance compared to conventional DIBs using metal anodes.