Synthesis and Sodium-Ion Storage of Triazole-Substituted Graphdiyne

Sodium-ion batteries (SIBs) have developed rapidly in recent years, confronting low capacity and poor cycling stability issues for anode material. Herein, triazole-substituted graphdiyne (TzlGDY) was designed to tune the sodium-ion insertion sequence, and an effective diyne-radical Na-storage mechanism was discovered. The distinctive diyne-ditriazole architecture actualizes a preferential Na⁺-N complexation, then π-bond homolysis of diyne is induced by Na⁺ to generate two radicals at two end carbons of diyne, and thereby two radicals capture two additional Na⁺ by Na⁺-radical coupling. This Na⁺-N complexation followed by the Na⁺-radical coupling mechanism more effectively enhances capacity compared with the reported cation-π mechanism. Furthermore, other ditriazole-N atoms chelate two more Na⁺. The triazole-filled nanopores and full-carbon backbone in TzlGDY effectively stabilize diyne radicals and enhance the Na⁺-transport kinetics. As a result, TzlGDY's anode presented almost no capacity decay over 12,000 cycles at 5 A g^-1 with a final capacity of 251.7 mAh g^-1. Moreover, the TzlGDY||NVP full cell delivered a high specific capacity of 114 mAh g^-1 at 0.2C with a capacity retention of 81.8% and an average CE of 99.6% after 150 cycles. Our results demonstrate the diyne-radical mechanism is a new concept of energy storage and open up a new route for efficiently regulating anode materials in SIBs.