Preparation And Electrochemical Properties Of Germanium On Nickel Current Collector

Germanium is attractive as an anode material for lithium ion batteries because ithas a high theoretical capacity of1600mAh g-1, based on the formation of Li4.4Ge, aswell as high lithium diffusivity and electrical conductivity. However, Ge suffers from alarge, volume change during the (de)alloying process, the strain of which potentiallyleads to pulverisation of the local structure and electrical disconnect from the currentcollector; such an effect results in a marked loss of capacity and cycle performance。Bystudying the different structures of the topic Nickel collector, the electrochemicalproperties of germanium are improved.Firstly, the electrochemical performance of germanium film anode materialsprepared by the method of ionic liquid electrodeposition on the nickel foil has beenstudied. Studies show that, after100cycles, the specific capacity of the germaniumfilm decreases from800mAh g-1to200mAh g-1. Germanium poor electrochemicalperformance on the nickel foil which due to the large volume changes during thelithium insertion/extraction process, can lead to cracking and disintegration of the Geelectrode, which results in electrode materials falling off from the current collector andconductivity losing as well as severe capacity fading.Further research of the germanium material’s electrochemical properties, on Ninanocone-arrays current collector, has been carried out. The research shows that thecurrent density and time will affect the morphology of electrodeposited Ninanocone-arrays. The results show that a good morphology of Ni nanocone-arrays canbe obtained, when the current density is25mA/cm2and the deposition time is4min.the specific capacity of the germanium on it is still remained500mAh g-1after100charge-discharge cycles, and the cycle efficiency is more than97%.Finally, we study the electrochemical properties of3DOM germanium anodematerials on nickel collector.3DOM germanium is prepared by two methods. One is toprepare3DOM germanium by using a template on nickel foil, and another is to prepare3DOM Ni, where the ionic germanium is deposited by the method of ionic liquidelectrodeposition. The results showed that, compared to the unsupported3DOMgermanium, the germanium on3DOM Ni boned having a good electrochemicalproperties, and the cycle performance and rate performance has been greatly improved. Higher capacity is maintained after the high-rate charge-discharge cycles. This isbecause the3DOM Ni prevents the collapse of the structure of3DOM germanium,which ensures the integrity of the active materials.