Enhancing the electrochemical performance of germanium-modified Li-rich Li1.2Ni0.2Mn0.6O2 through simultaneous surface and bulk phase modifications

IF 5.3 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Materials Research Bulletin Pub Date : 2025-02-27 DOI:10.1016/j.materresbull.2025.113408

Chen Wu , Shibo Liu , Kejing Song , Yongda Cao , Wenhan Wang , Xingyu Lai , Yuan Wang

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Abstract

Lithium-rich layered oxide (Li_1.2Ni_0.2Mn_0.6O₂) is a promising cathode material for lithium-ion batteries. However, its performance is hindered due to the instability of oxygen redox reactions at high potentials. Herein, a germanium (Ge) doping strategy was proposed by adding GeO₂ to the lithiation process. GeO₂ reacts with Li₂CO₃ to form a lithium germanate (Li₂GeO₃) layer (∼5 nm thick) on the Li_1.2Ni_0.2Mn_0.6O₂ surface, acting as a protective “armor” to suppresses side reactions. The Li₂GeO₃ layer with high Li-ions conductivity can accelerate the ion transport in bulk phase. Additionally, Ge ions can diffuse into the Li_1.2Ni_0.2Mn_0.6O₂ lattice during calcination, reducing cation mixing (Li⁺/Ni²⁺). XPS analysis confirms that Ge incorporation promotes Ni²⁺ oxidation to Ni³⁺, enhancing cation order and further minimizing cation mixing. The Li₂GeO₃-modified Li_1.2Ni_0.2Mn_0.6O₂ (G2, with 2 mol% GeO₂) delivers a reversible discharge capacity of 180.9 mAh g^-1 at 1 C, maintaining 75.41% capacity retention at 2 C after 500 cycles.

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通过同时进行表面和体相改性，提高锗改性富锂Li1.2Ni0.2Mn0.6O2的电化学性能

富锂层状氧化物（Li1.2Ni0.2Mn0.6O2）是一种很有前途的锂离子电池正极材料。然而，由于在高电位下氧氧化还原反应的不稳定性，它的性能受到阻碍。本文提出了在锂化过程中加入GeO2掺杂锗（Ge）的策略。GeO2与Li2CO3反应，在Li1.2Ni0.2Mn0.6O2表面形成约5 nm厚的锗酸锂（Li2GeO3）层，起到抑制副反应的保护性“盔甲”作用。具有高锂离子电导率的Li2GeO3层可以加速离子在体相中的输运。此外，在煅烧过程中，Ge离子可以扩散到Li1.2Ni0.2Mn0.6O2晶格中，减少阳离子混合（Li+/Ni2+）。XPS分析证实，Ge的掺入促进了Ni2+氧化为Ni3+，增强了阳离子的秩序，进一步减少了阳离子的混合。li2geo3修饰的li1.2 ni0.2 mn0.62 o2 （G2，含2mol %的GeO2）在1c条件下的可逆放电容量为180.9 mAh g-1，在2 C条件下循环500次后保持75.41%的容量保持率。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Materials Research Bulletin 工程技术-材料科学：综合

CiteScore

9.80

自引率

5.60%

发文量

372

审稿时长

42 days

期刊介绍： Materials Research Bulletin is an international journal reporting high-impact research on processing-structure-property relationships in functional materials and nanomaterials with interesting electronic, magnetic, optical, thermal, mechanical or catalytic properties. Papers purely on thermodynamics or theoretical calculations (e.g., density functional theory) do not fall within the scope of the journal unless they also demonstrate a clear link to physical properties. Topics covered include functional materials (e.g., dielectrics, pyroelectrics, piezoelectrics, ferroelectrics, relaxors, thermoelectrics, etc.); electrochemistry and solid-state ionics (e.g., photovoltaics, batteries, sensors, and fuel cells); nanomaterials, graphene, and nanocomposites; luminescence and photocatalysis; crystal-structure and defect-structure analysis; novel electronics; non-crystalline solids; flexible electronics; protein-material interactions; and polymeric ion-exchange membranes.