Reversible lithium storage behaviour of aromatic diimide dilithium carboxylates

Electrochemical lithiation/delithiation studies are carried out on three different aromatic diimide lithium carboxylates. Among all, naphthalene diimide based dilithium carboxylate delivers a remarkably stable capacity of 134 mAh g−1 at 2.24 V vs. Li/Li+ over 125 cycles with a low polarization of 50 mV. A striking feature is that, the lithiation/delithiation process is biphasic with excellent plateau behaviour in the voltage-composition profile. DFT calculations confirm the lower band gap and higher electron affinity for this compound.