Lithium and Potassium Cations Affect the Performance of Maleamate-Based Organic Anode Materials for Potassium- and Lithium-Ion Batteries

Abstract

In this study we prepared potassium-ion batteries (KIBs) displaying high output voltage and, in turn, a high energy density, as replacements for lithium-ion batteries (LIBs). Organic electrode materials featuring void spaces and flexible structures can facilitate the mobility of K+ to enhance the performance of KIBs. We synthesized potassium maleamate (K-MA) from maleamic acid (MA) and applied as an anode material for KIBs and LIBs, with 1 M potassium bis(fluorosulfonyl)imide (KFSI) and 1 M lithium bis(fluorosulfonyl)imide (LiFSI) in a mixture of ethylene carbonate and ethyl methyl carbonate (1:2, v/v) as respective electrolytes. The K-MA_KFSI anode underwent charging/discharging with carbonyl groups at low voltage, due to the K···O bond interaction weaker than Li···O. The K-MA_KFSI and K-MA_LiFSI anode materials delivered a capacity of 172 and 485 mA h g−1 after 200 cycles at 0.1C rate, respectively. K-MA was capable of accepting one K+ in KIB, whereas it could accept two Li+ in a LIB. The superior recoveries performance of K-MA_LiFSI, K-MA_KFSI, and Super P_KFSI at rate of 0.1C were 320, 201, and 105 mA h g−1, respectively. This implies the larger size of K+ can reversibly cycling at high rate.

Progress and Prospects of Emerging Potassium–Sulfur Batteries

“…When a thick and non‐uniformal SEI exists, more heterogeneities will be produced and an enhanced electric field is unnecessary. [ 68b,74 ] The potassium growth speed can be increased in some areas of the SEI, which are elastically softer, for instance, areas with pores and cracking. These areas accelerate K + ion diffusion and create priority nucleation sites including oxide and fluoride particles.…”

“…Furthermore, with a low reduction potential ( E o (K/K + ) = −2.93 V versus the standard hydrogen redox potential), K could offer a high operating voltage and good gravimetric capacity. [ 7 ] These advantages have made K the focus of increasing attentions. For instance, K is capable of insertion and extraction into/from graphite anode at low rates, where potassium graphite can be formed with a capacity of 278 mAh g −1 .…”