Using an organic acid as a universal anode for highly efficient Li-ion, Na-ion and K-ion batteries

Terephthalic acid (H 2 TP) is initially unveiled to be the first example of organic anodes exhibiting the universal Li-ion, Na-ion and K-ion storage capabilities. In Li-ion half cells, H 2 TP can deliver the average capacities of ∼235 mAh g −1 for 500 cycles; In Na-ion half cells, H 2 TP is reported to deliver the average capacities of ∼200 mAh g −1 for 50 cycles; and in K-ion half cells, H 2 TP can exhibit the average capacities of ∼240 mAh g −1 for 150 cycles. At the same time, the chemical structure and crystal structure of H 2 TP could be transformed into its related metal salts on the anode side due to the low reduction potential. This work indicates that organic electrode materials should own the universal metal-ion-storage (e.g., Li + , Na + , K + , etc.) capability for their large void room of organic solid/crystal state.