Corrugated Layered Titanates as High-Voltage Cathode Materials for Potassium-Ion Batteries

Abstract

Layered transition metal oxides with two-dimensional diffusion pathway and high theoretical energy density are promising cathode candidates for potassium-ion batteries (PIBs). Nevertheless, the large size of K+ increases the K+–K+ electrostatic repulsion in the layered structure, resulting in the low operating voltage in PIBs, which remains a great challenge to be solved. Herein, we develop a series of corrugated layered titanates that extend the K+–K+ distance to ∼3.9 Å, exceeding the K+–K+ distance of all reported layered oxides. By shielding the K+–K+ electrostatic repulsion, K0.8Mn0.8Ti1.2O4 and K0.8Ni0.4Ti1.6O4 as corrugated layered titanate representatives furnish high working voltages of 3.0 and 3.6 V, respectively. In addition, K0.8Mn0.8Ti1.2O4 also achieves a large reversible capacity of 77.8 mAh g–1 and a long lifetime over 300 cycles. In situ X-ray diffraction measurements indicate that K0.8Mn0.8Ti1.2O4 exhibits reversible structural evolution during de/potassiation with a lattice volume change as low as 1.4%. These findings provide new insights for the further development high-voltage layered cathodes for PIBs.

Advancements in cathode materials for potassium-ion batteries: current landscape, obstacles, and prospects

“…For example, a representative layered titanate such as K 0.8 Ni 0.4 Ti 1.6 O 4 (Fig. 21a) exhibits a high working voltage of 3.6 V. 256 Fig. 21b and c show the voltage-capacity profiles of K 0.8 Ni 0.4 Ti 1.6 O 4 and K 0.8 Co 0.8 Ti 1.2 O 4 .…”

“…A series of corrugated layered titanates, 255 including K 0.8 M 0.8 Ti 1.2 O 4 ( M = V, Cr, Mn, Fe and Co), K 0.6 Cr 0.6 Ti 0.4 O 2 , etc. , 256 with longer K + –K + distances (of ∼3.9 Å) compared to conventional K x MO 2 layered oxides' (typically ∼3.0 Å), 232 have been found to effectively mitigate the K + –K + electrostatic repulsion, resulting in high voltages with minimal phase transitions. For example, a representative layered titanate such as K 0.8 Ni 0.4 Ti 1.6 O 4 (Fig.…”

Advances in Fine Structure Optimizations of Layered Transition‐Metal Oxide Cathodes for Potassium‐Ion Batteries

“…There are mainly two coordination environments for alkali ions in A 1‐ x MO 2 : face shared prismatic (P) and edge‐sharing octahedral (O) sites. [ 64 ] Here, the number of MO 6 layers in one repetitive stacking unit is 3 or 2 ( Figure 2 ). For instance, O2 and O3 phases are stacked in an ABAC and ABCABC pattern with the octahedral‐alkali‐metal, respectively.…”

N-Doped Carbon Knotting Carbon Nanotube Sponge Networks for Lithium-Ion Capacitor Anodes

“…To meet the urgent energy demand, advanced energy storage systems have been rapidly developed and extensively studied in recent years. − Among them, the lithium-ion capacitor (LIC) is a hybrid device consisting of a battery-type anode and a capacitor-type cathode in an electrolyte containing lithium salt. During the charging–discharging processes, Li ions are repeatedly inserted/extracted on the anode materials, and electrolyte anions are adsorbed/desorbed on the surface of the cathode materials. , Thus, the LIC has the advantages of both a lithium-ion battery (LIB) and a supercapacitor.…”