Regulating Dynamic Electrochemical Interface of LiNi0.5Mn1.5O4 Spinel Cathode for Realizing Simultaneous Mn and Ni Redox in Rechargeable Lithium Batteries

Gukhyun Lim, Dongki Shin, Keun Hwa Chae, Min Kyung Cho, Chan Kim, Seok Su Sohn, Minah Lee, Jihyun Hong

Research output: Contribution to journalArticlepeer-review

Abstract

The exploding electric-vehicle market requires cost-effective high-energy materials for rechargeable lithium batteries. The manganese-rich spinel oxide LiNi0.5Mn1.5O4 (LNMO) can store a capacity greater than 200 mAh g−1 based on the multi-cation (Ni2+/Ni4+ and Mn3+/Mn4+) redox centers. However, its practical capacity is limited to Ni2+/Ni4+ redox (135 mAh g−1) due to the poor reversibility of Mn3+/Mn4+ redox. This instability is generally attributed to the Jahn–Teller distortion of Mn3+ and its disproportionation, which leads to severe Mn dissolution. Herein, for the first time, the excellent reversibility of Mn3+/Mn4+ redox within 2.3–4.3 V is demonstrated, requiring revisiting the previous theory. LNMO loses capacity only within a wide voltage range of 2.3–4.9 V. It is revealed that a dynamic evolution of the electrochemical interface, for example, potential-driven rocksalt phase formation and decomposition, repeatedly occurs during cycling. The interfacial evolution induces electrolyte degradation and surface passivation, impeding the charge-transfer reactions. It is further demonstrated that stabilizing the interface by electrolyte modification extends the cycle life of LNMO while using the multi-cation redox, enabling 71.5% capacity retention of LNMO after 500 cycles. The unveiled dynamic oxide interface will propose a new guideline for developing Mn-rich cathodes by realizing the reversible Mn redox.

Original languageEnglish
Article number2202049
JournalAdvanced Energy Materials
Volume12
Issue number46
DOIs
Publication statusPublished - 2022 Dec 8

Keywords

  • EC-free electrolytes
  • Mn-rich cathodes
  • cathode-electrolyte interfaces
  • multi-cation redox
  • rechargeable Li batteries
  • spinel oxides
  • surface reconstruction

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)

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