Imaging nanospaces with x-ray ptychography – a comprehensive tool
Dr. Johanna Weker
Li-ion batteries rule the world of mobile devices. However, they are still in their infancy when it comes to powering up automobiles. Higher capacity and long lasting life are the keys to exploit them in automobile industry. Why is developing high performance Li-ion batteries a challenge?
During the battery operation, the electrode components undergo irreversible changes chemically, structurally and morphologically which are harder to pinpoint with presently available tools. Electrode components are made from microsized particles and often nanoparticles (1 nm = 1000,000 times smaller than the thickness of a human hair). A central mechanism that governs all lithium ion type batteries, including the one that we use everyday is, “shuttling of Li – ions between cathode and anode during charge/discharge cycle.
What do you infer from the picture below?
A micrometer-sized particle is swelling and breaking apart. And what If I tell you this particle makes the electrode in your cell phone battery? Shocking? What you see is an agglomerate of Ge nanoparticles that form the cathode in Ge-Li battery imaged by transmission x-ray microscopy (TXM) in tomography mode (3D), “in operando” – meaning imaging while the battery is being charged and discharged. As the particles that make up the electrode pulverize, they lose electrical contact with each other sabotaging battery capacity and lifetime. Ge based electrodes in a Li-ion rechargeable battery could offer four times higher power than the currently used Li-ion battery types. But this irreversible damage of electrodes prevents us from taking advantage of Ge based Li-ion batteries.