Multiphase Riveting Structure for High Power and Long Lifespan Potassium‐Ion Batteries

Abstract

The development of potassium‐ion batteries (KIBs) relies on the exploration of stable layer‐structured oxide cathode materials and a comprehensive understanding of ion storage and diffusion behaviors. A multiphase riveting‐structured O3/P2/P3‐Na0.9[Ni0.3Mn0.55Cu0.1Ti0.05]O2 (Tri‐NMCT) is employed as cathode material for KIBs. It demonstrates an initial discharge specific capacity of 108 mA g−1 at current density of 15 mA g−1 in the voltage range of 1.5–4 V. Excellent cyclic stability is exhibited as well with a high 83% capacity retention after 600 cycles at a higher current density of 300 mA g−1. Based on the in‐situ XRD, it reveals that the P2 phase offers a more stable triangular prism site compared to the O3 phase. This stability inhibits the undesired phase transition from P3 to O3 during discharge, thereby ensuring the long‐term cyclic performance. Furthermore, Density of state (DOS) calculations and migration barrier analyses indicate a preferential migration of K+ ions to the P2 phase due to the lower Fermi level. This observation elucidates the structural preservation of the P3 phase during K+ embedding. Overall, this work sheds light on Tri‐NMCT as a promising cathode material for advanced KIBs.

Realizing a single-phase reaction and K+/vacancy disordering in P2-K0.56Na0.11Li0.12Ni0.22Mn0.66O2 by lithium substitution for potassium-ion batteries

“…As the discharging continues, the K + /Na + mixed phase (P2-K/Na) appeared at 15.3° and 30.6°, consistent with previous reports. 36 According to inductively coupled plasma mass spectroscopy (ICP-MS) results (Table S3†), the atomic ratio of K, Na, Ni, and Mn was identified to be 0.43 : 0.34 : 0.22 : 0.66. Ex-situ XRD tests of various cycled electrodes at the end of discharge were carried out to further analyze the structural change (Fig.…”

A synergistic pinning effect in a layer-structured oxide cathode for enhancing stability towards potassium-ion batteries

“…This process was repeated within a voltage window of 1.5–4.0 V. During the titration process, a linear relationship can be established between the battery voltage and τ 1/2 , whereby the chemical diffusion coefficient of K + in the electrode can be determined using the following equation (eqn (2)). 52 …”

Recent advances in rational design for high-performance potassium-ion batteries

“…As discussed above, the role of Mg 2+ or Ti 4+ in the partial substitution of Mn 3+ is to effectively maintain a single-phase reaction and improve the cycling stability. 64,173,189 This also applies to multi-element electrodes. Both P3-type K 0.45 Co 1/12 Mg 1/12 Mn 5/6 O 2 and P3-type K 0.4 Fe 0.1 Mn 0.8 Ti 0.1 O 2 have been demonstrated as cathode materials for PIBs with high structural reversibility.…”

“…Xu et al 192 found that partial replacement of O 2− with F − could extend the interlayer distance of K 2/3 Mn 7/9 Ni 1/9 Ti 1/9 O 2 and counteract their capacity fading at high voltage (>4.0 V vs. K + /K). Recently, Liu et al 64 prepared a multiphase riveted structure O3/P2/P3-Na 0.9 [Ni 0.3 Mn 0.55 Cu 0.1 Ti 0.05 ]O 2 (Tri-NMCT) as a PIB cathode material. Among them, the O3 phase and P3 phase serve as the main storage sites for K + .…”