Electrolyte Effect on a Polyanionic Organic Anode for Pure Organic K-Ion Batteries

Potassium naphthalene-1,4,5,8-tetracarboxylate (K₄NTC, 117 mAh g^-1) is a new organic anode for K-ion batteries, which possesses four strong K-O ionic bonds within a -4-valent naphthalene-1,4,5,8-tetracarboxylate skeleton (NTC^4-). And thus, K₄NTC is a polyanionic organic salt. Simultaneously, new insights are provided by comparing two typical electrolyte systems (carbonate and ether electrolytes) with KPF₆ as the same solute. Finally, the pure organic K-ion batteries (OKIBs) are fabricated by using perylene-3,4,9,10-tetracarboxydianhydride (PTCDA) as the organic cathode and the reduced state (K₆NTC) of K₄NTC as the anode. And this OKIB can deliver a peak discharge capacity of 121 mAh g^-1_anode and run over 1500 cycles in 0.5-3 V using ether electrolytes.