Achieving ultra-long cycling life for MnO₂ cathode: Modulating Mn³⁺ spin state to suppress Jahn–Teller distortion and manganese dissolution

TY - JOUR

T1 - Achieving ultra-long cycling life for MnO2 cathode

T2 - Modulating Mn3+ spin state to suppress Jahn–Teller distortion and manganese dissolution

AU - Zhang, Ziyi

AU - Zheng, Jie

AU - Chen, Xinya

AU - Yu, Xinyu

AU - Li, Lijie

AU - Bao, Lixia

AU - Peng, Jiong

AU - Li, Xin

N1 - Publisher Copyright: © 2025 Elsevier B.V.

PY - 2025/3

Y1 - 2025/3

N2 - MnO2 is emerging as an electrode material for sodium-ion capacitors due to its high specific capacity and low cost. However, Jahn-teller distortion and manganese dissolution pose a formidable challenge in practical applications. Herein, the Mn3+ spin state, causing J-T distortion, is modulated to address these issues, which is achieved through strategically incorporating Co into the MnO2 lattice to increase electron occupancy in the t2g orbital. The transition from a high-spin Mn3+ to a low-spin state leads to electron movement from the dx2-y2 orbitals to the dxy orbitals, which effectively lowers the energy level of the eg orbitals, reduces orbital degeneracy, and enhances the stability of the Mn-O bond. DFT calculations, In situ Raman and inductively coupled plasma optical emission spectroscopy (ICP-OES) demonstrate that the distortion of [MnO6] and Mn dissolution of Co-MnO2 are reduced by 69 % and 80 % respectively compared with MnO2 during the charge-discharge cycle. Consequently, Co-MnO2 exhibits approximately 98 % capacity retention after 40,000 cycles at 10 A/g, achieving exceptional long-term stability. This study provides new insights into the relationships among J-T distortion, manganese dissolution and spin state, provides a novel approach to enhance the stability of MnO2 for electrochemistry applications.

AB - MnO2 is emerging as an electrode material for sodium-ion capacitors due to its high specific capacity and low cost. However, Jahn-teller distortion and manganese dissolution pose a formidable challenge in practical applications. Herein, the Mn3+ spin state, causing J-T distortion, is modulated to address these issues, which is achieved through strategically incorporating Co into the MnO2 lattice to increase electron occupancy in the t2g orbital. The transition from a high-spin Mn3+ to a low-spin state leads to electron movement from the dx2-y2 orbitals to the dxy orbitals, which effectively lowers the energy level of the eg orbitals, reduces orbital degeneracy, and enhances the stability of the Mn-O bond. DFT calculations, In situ Raman and inductively coupled plasma optical emission spectroscopy (ICP-OES) demonstrate that the distortion of [MnO6] and Mn dissolution of Co-MnO2 are reduced by 69 % and 80 % respectively compared with MnO2 during the charge-discharge cycle. Consequently, Co-MnO2 exhibits approximately 98 % capacity retention after 40,000 cycles at 10 A/g, achieving exceptional long-term stability. This study provides new insights into the relationships among J-T distortion, manganese dissolution and spin state, provides a novel approach to enhance the stability of MnO2 for electrochemistry applications.

KW - Jahn-Teller distortion

KW - Manganese dissolution

KW - Mn3+ spin state

KW - Modulate

UR - https://www.scopus.com/pages/publications/85218421940

U2 - 10.1016/j.ensm.2025.104128

DO - 10.1016/j.ensm.2025.104128

M3 - Article

AN - SCOPUS:85218421940

SN - 2405-8297

VL - 76

JO - Energy Storage Materials

JF - Energy Storage Materials

M1 - 104128

ER -