Para-Conjugated Dicarboxylates with Extended Aromatic Skeletons as the Highly Advanced Organic Anodes for K-Ion Battery

A new family of the para-conjugated dicarboxylates embedding in biphenyl skeletons was exploited as the highly advanced organic anodes for K-ion battery. Two members of this family, namely potassium 1,1'-biphenyl-4,4'-dicarboxylate (K2BPDC) and potassium 4,4'E-stilbenedicarboxylate (K2SBDC), were selectively studied and their detailed redox behaviors in K-ion battery were also clearly unveiled. Both K2BPDC and K2SBDC could exhibit very clear and highly reversible two electron redox mechanism in K-ion battery, as well as higher potassiation potentials (above 0.3 V vs K+/K) when compared to the inorganic anodes of carbon materials recently reported. Meanwhile, the satisfactory specific and rate capacities could be realized for K2BPDC and K2SBDC. For example, the (KBPDC)-B-2 anode could realize the stable rate capacities of 165/143/135/ 99 mAh g(-1) under the high current densities of 100/200/500/1000 mA respectively, after its electronic conductivity was improved by mixing a very small amount of graphene. More impressively, the average specific capacities K2BPDC anode for 3000 cycles under the high current density of 1 A g(-1).