Porous carbon microspheres with highly graphitized structure for potassium-ion storage

Research progress on carbon materials as negative electrodes in sodium‐ and potassium‐ion batteries

“…The carbon microspheres prepared by them had a low working potential of ~0.2 V, high Coulombic efficiency, and stable reversible capacity of 292.0 mAh g −1 after 100 cycles. 216 Zhang et al successfully fabricated a mesoporous carbon nanosheet assembled flower as a PIB negative electrode material with 381 mAh g −1 at 50 mA g −1 , 101 mAh g −1 at 2.0 A g −1 , and ultra-long cycle stability of over 600 cycles at 500 mA g −1 . 222 Zhang et al 223 synthesized a high N-doped (26.7 at%) accordion-like carbon negative by direct pyrolysis, which was composed of thin carbon nanosheets and a turbine translation crystal structure (Figure 15A-C).…”

“…To sum up, both SIBs and PIBs require nanoscale materials to achieve high rate capacity as both sodium and potassium ions are larger than lithium ions. 216 Nanostructured materials have unique physical and chemical properties, with a large surface area, increasing the electrode/electrolyte contact area and active center, making rapid ion transport at the electrode/ electrolyte interface possible. In addition, the nanostructure design is often accompanied by the improvement of the electrical conductivity of the material, which can effectively shorten the path of electron transport, thus accelerating the diffusion of Na + /K + in the bulk phase.…”

“…(C) Schematic diagram illustrating the synthesis of carbon particles and (D,E) transmission electron microscopy images of C‐2100. Reproduced with permission: Copyright 2020, Elsevier 216 …”

Potassium-ion batteries: outlook on present and future technologies

“…After 350 cycles at 0.4 A g -1 , the capacity retention rate can keep 75%. Choi et al 146 demonstrated the porous carbon microspheres with highly graphitized structure for potassium-ion storage, which exhibit a stable specific capacity of 292.0 mAh g -1 after 100 cycles. The high crystallinity and porous structure are critical to the desirable performances, which could alleviate the stress caused by the large volume expansion during the K-insertion/extraction.…”

Highly Dispersed Antimony–Bismuth Alloy Encapsulated in Carbon Nanofibers for Ultrastable K-Ion Batteries

“…A continuous increase in cost has largely hindered the deep-level application of LIBs in energy storage systems. − Potassium ion batteries (KIBs) have drawn widespread attention in recent years because of the low redox potential of K + /K, rich reserves, and the competitive cost of potassium resources. The working principle of KIBs is similar to LIBs. − Since the standard electrode potential of K/K + is closer to that of Li/Li + , potassium ion batteries have advantages over sodium ion batteries in output voltage and energy density. Since the Lewis acidity of K + is weaker than that of Li + and Na + , K + migrates faster in the electrolyte and in the interface between an electrolyte and electrode, which may promote the KIBs to have a superior rate capability. − However, the large ion radius of K + has become the main factor restricting the development of K-ion storage materials. − Therefore, exploration of electrode materials, in particular, high capacity anodes, is highly demanded to promote the application of KIBs …”