Exploring enhanced capacity in lithium-ion battery anodes: Synthesis and electrochemical evaluation of Zn2GeO4 encapsulated in porous carbon balls via carbonization

Abstract

Germanium-based materials, such as Zn2GeO4, have recently been attracting attention as anode materials that can be used as an alternative to graphite. However, Zn2GeO4 suffers from critical disadvantages—such as low electrical conductivity and volume expansion—during lithiation/de-lithiation processes, which lead to reduced cycling stability and low specific capacity. In this study, we proposed the concept of porous carbon ball-encapsulated Zn2GeO4. The porous carbon balls were synthesized using heat treatment to be used as a buffer, with the effectively mitigating the volume expansion of Zn2GeO4. We investigated the electrochemical properties and mechanisms of Zn2GeO4 during cycling using ex-situ XRD analysis. The final product (H-C@ZGO) demonstrated enhanced cycling stability, with capacities ranging from 550 to 660 mAhg−1 at 0.1 Ag−1. We also examined the improved diffusion pathways facilitated by the encapsulated carbon balls as well as the porous structure formed by heat treatment. © 2024 The Authors