Carbonized bacterial cellulose as free-standing cathode host and protective interlayer for high-performance potassium-sulfur batteries with enhanced kinetics and stable operation

Abstract

Due to the limited capacity of Lithium (Li)-ion batteries and the scarce reserves of Li, potassium-sulfur battery (KSB) seems to be the most appealing candidate for next-generation advanced energy storage systems owing to the abundance of sulfur as well as potassium in addition to the high capacity offered by sulfur cathodes. However, the development of KSB is in the nascent stage, primarily because of the highly unstable and reactive potassium anode, which needs special consideration for its protection. To overcome this, for the first time to the best of our knowledge, we introduce the free-standing carbonized bacterial cellulose (CBC) not only as an anode-protective interlayer but also as a cathode host. Further, the K2S6 catholyte is used as an active material, enabling the even distribution of active sulfur and high sulfur loading. Benefitting from the superior physicochemical properties of CBC and the introduction of it as a protective interlayer, the KSB, as developed, can be cycled for continuous 500 cycles even at high current rates such as 2 and 5C, respectively. The cell with CBC as a cathode host and an interlayer retained 73% and 62% of initial capacity after 300 and 500 cycles at 1 and 2C, respectively. Potassium striping and plating test show that the CBC interlayer effectively enables uniform nucleation and growth, reducing dendrite formation. The first-principles calculations are also performed to substantiate these advancements in electrochemical performances. This study may pave the way for the practical realization of KSB with stable operation and long cycle life.