An Ultrafast and Highly Stable Potassium–Organic Battery

Abstract

Na: −2.71 V vs E 0 , Mg: −2.37 V vs E 0 , and Al: −1.66 V vs E 0 ). [28][29][30][31] Up to now, the most investigated cathode materials for PIBs are Prussian blue analogues, [32][33][34][35][36][37][38] layered oxides, [39][40][41][42][43][44][45] and organic cathodes. [30,[46][47][48] Specially, the organic electrodes are highly promising for PIBs, considering their low cost, abundance, eco-friendliness, easiness for mass production, and structural diversity. Though tremendous progress has been achieved in LIBs and sodium-ion batteries (SIBs) by using organic materials as the cathode, the research on organic electrodes for PIBs is sluggish and tepid, which is not merely due to their inferior electrical conductivity but also because of the low rate performance and inferior cycle stability. Moreover, the mass loading, cycle stability, rate performance, and power density of organic cathodes in PIBs are pretty poor, in comparison to the LIBs and SIBs. Therefore, the research on organic cathodes for PIBs has been shelved, even though there are a few reports about the organic cathodes for PIBs. [30,[46][47][48] To overcome these challenges, we developed an ultrafast and highly stable potassium-organic battery using a highly conductive organic cathode in combination with an optimized electrolyte. Consequently, the battery could deliver a high reversible capacity of 126 mA h g −1 at 100 mA g −1 , a superior rate performance (84 mA h g −1 at 5000 mA g −1 ), a high energy density (300.5 W h kg −1 at a power density of 246.3 W kg −1 ), a high power density (9796 W kg −1 at an energy density of 168.5 W h kg −1 ), a long cycle stability (1000 cycles with a capacity of 87.6% at 1000 mA g −1 ), and a high energy efficiency of 89%. Notably, even at an ultrahigh loading of 19.5 mg cm −2 for the active material, it still could deliver a capacity over 101 mA h g −1 (around 2 mA h cm −2 ) and maintain a cycle stability over 550 cycles (more than 8 months). Besides, full cells with this cathode exhibited a superior rate performance and cycle stability. This paper demonstrates the enormous potential of this organic cathode for high power PIBs application and may pave the way for the commercialization of PIBs.Perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA), the "red 224" pigment, was selected as the organic cathode because of its high capacity and stability in LIBs and SIBs. [49,50] The storage mechanism of PTCDA is that the CO bonds in the PTCDA could transform to COM (M means metal ion, Li, Na, K) when the storage process occurs, and it will return to CO during the deintercalation process. However, the cycle performance and rate performance were inferior for PIBs, according to the literature due to the low electric conductivity and solubleness. [46,48] Hence, in order to enhance the Potassium-organic batteries have a great potential for applications in the grid-scale energy storage owing to their low cost and abundant resources, although they suffer from the inferior cycle stability, fast capacity decay, and low power dens...

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