Sythesis And Lithium Storage Performance Of Germanium-based Oxynitrides Materials

Among various lithium-ion battery（LIB）anode materials,germanium-based oxynitrides have attracted widespread attention in the field of electrochemical energy storage due to their excellent chemical stability and high theoretical capacity.However,poor conductivity,low practical discharge specific capacity,and unsatisfactory rate performance have greatly limited the extensive application of germanium-based oxynitrides in the field of electrochemical energy storage.Therefore,developing new germanium-based oxynitrides and modifying existing germanium-based nitride oxide lithium-ion battery anode materials while ensuring their cycle stability are the focus of current research.This study employs strategies such as morphology control,metal element doping,and carbon-based conductive material composites to enhance the lithium storage performance of germanium-based nitride oxide electrode materials and conduct an in-depth investigation of their lithium storage mechanisms.The specific research content is as follows:（1）Cobalt-doped Ge Zn_1.7ON_1.8(Co-Ge Zn_1.7ON_1.8)particles were prepared using a one-step ammoniation method.The successful doping of cobalt was confirmed by XRD,XPS,and EPR test results.Compared to the pristine Ge Zn_1.7ON_1.8,Co-Ge Zn_1.7ON_1.8 exhibits superior charge-discharge specific capacity,longer cycle stability,and exceptional rate performance.GITT analysis further demonstrates that the doping of cobalt significantly improves the lithium-ion diffusion rate,which is the main reason for the enhanced electrochemical performance of the Co-Ge Zn_1.7ON_1.8 electrode.Moreover,pseudocapacitive analysis indicates that the electrochemical process of Co-Ge Zn_1.7ON_1.8 is predominantly capacitance-controlled.Ex-situ XRD results confirm that Co-Ge Zn_1.7ON_1.8 possesses excellent structural stability and a reversible lithium-ion deintercalation reaction mechanism.（2）The Fe₄Ge N@r GO composite material was prepared through a two-step method combining hydrothermal and ammoniation processes.XRD,SEM,and TEM results confirm the successful combination of Fe₄Ge N and r GO.As a lithium-ion battery anode material,Fe₄Ge N@r GO demonstrates higher charge-discharge specific capacity,rate performance,and cycle stability.Ex-situ XRD results indicate that the excellent structural stability and reversible deintercalation lithium storage mechanism of Fe₄Ge N@r GO electrode ensure its superior electrochemical performance.The introduction of r GO effectively reduces the reaction resistance of the material,thereby improving its conductivity and lithium-ion transport capabilities.（3）GeO₂ nanowires composite with Mn O₂（GeO₂@Mn O₂）material was prepared using the hydrothermal method.XRD and TEM mapping tests confirm the successful combination of GeO₂ and Mn O₂.Compared to GeO₂and Mn O₂ electrodes,the GeO₂@Mn O₂ nanowire electrode exhibits more stable cycle stability and higher reversible charge-discharge specific capacity.SEM and TEM results indicate that the network structure formed by GeO₂@Mn O₂ nanowires facilitates the enhancement of electron transfer efficiency and ion diffusion speed during the charge-discharge process.Ex-situ XRD results demonstrate that GeO₂@Mn O₂ nanowires employ a conversion reaction lithium storage mechanism.