Entropy-Stabilized Layered K0.6Ni0.05Fe0.05Mg0.05Ti0.05Mn0.725O2 as a High-Rate and Stable Cathode for Potassium-Ion Batteries

Yuqing Cai; Wenjing Liu; Fangfei Chang; Su Jin; Xusheng Yang; Chuanxiang Zhang; Ling Bai; Titus Masese; Ziquan Li; Zhen-Dong Huang

doi:10.1021/acsami.3c11059

Entropy-Stabilized Layered K_0.6Ni_0.05Fe_0.05Mg_0.05Ti_0.05Mn_0.725O₂ as a High-Rate and Stable Cathode for Potassium-Ion Batteries

ACS Appl Mater Interfaces. 2023 Oct 18;15(41):48277-48286. doi: 10.1021/acsami.3c11059. Epub 2023 Oct 6.

Authors

Affiliations

¹ State Key Laboratory for Organic Electronics and Information Displays & Jiangsu Key Laboratory for Biosensors, Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing University of Posts and Telecommunications, 9 Wenyuan Road, Nanjing 210023, P. R. China.
² Department of Industrial and Systems Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon 999077, Hong Kong, P. R. China.
³ School of Materials Science and Engineering, Nanjing Institute of Technology, Nanjing 211167, Jiangsu, P. R. China.
⁴ Research Institute of Electrochemical Energy, Department of Energy and Environment (RIECEN), National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda 563-8577, Osaka, Japan.

PMID: 37801021
DOI: 10.1021/acsami.3c11059

Abstract

Mn-based layered oxides have been considered the most promising cathode candidates for cost-effective potassium-ion batteries (PIBs). Herein, equiatomic constituents of Ni, Fe, Mg, and Ti have been introduced into the transition metal layers of Mn-based layered oxide to design a high-entropy K_0.6Ni_0.05Fe_0.05Mg_0.05Ti_0.05Mn_0.0725O₂ (HE-KMO, S = 1.17R). Consequently, the experimental results manifest that the layered structure of HE-KMO is more stable than conventional low-entropy K_0.6MnO₂ (LE-KMO, S = 0.66R) during successive cycling and even upon exposure to moisture. Diffraction and electrochemical measurements reveal that HE-KMO undergoes a solid-solution mechanism, contrary to the multistage phase transition processes typically exemplified in K_0.6MnO₂. Benefiting from the stabilized high-entropy layered framework and the solid-solution K⁺ storage mechanism, the entropy-stabilized HE-KMO not only demonstrates exceptional rate capability but also shows excellent cyclic stability. Notably, a capacity retention ratio of 86% after 3000 cycles can still be sustained at a remarkable current density of 5000 mA g^-1.

Keywords: cathode materials; entropy stabilization effect; high entropy; potassium-ion batteries; transitional metal oxides.