Titanium Oxide-Based Additives in Iron Oxides as Electrode Materials for Solid-State Batteries

Clean energy technologies, such as electric vehicles (EVs) and stationary energy storage systems (ESSs), have become flourishing along with the increasing awareness of environmental protection in recent years. Rechargeable solid-state batteries (SSBs) exhibit the advantages of light weight, high energy density, good rate-capability, and safety, making them a vital choice for the applications of consumer electronics, EVs, and ESSs. However, poor structural stability and high cost impede the development of SSB's applications.<br/>Iron oxides exhibit the merits of high theoretical capacity, earth-abundance, lower carbon emission, and non-toxicity, suitable for being active materials in SSBs. However, iron oxides show the drawbacks of low electrical and Li-ionic conductivities, high volume expansion and easy to crack, and excess solid-electrolyte interphase (SEI) layers, during charge/discharge reactions. In this work, titanium oxide-based additives will be applied to iron oxides to improve structural stability and ion conductivity. It is expected that the additives can function as stabilizers to improve the structural stability of iron oxides, which can improve cycle stability and rate capability.<br/>The composition of titanium oxide-based additives in iron oxides will be optimized. The additives powders will be mixed with carbon black (super P), carboxymethyl cellulose (CMC), and styrene-butadiene rubber (SBR) to form an aqueous-based slurry. Following that, the slurry will be coated on a copper foil by doctor-blade casting as an electrode and baked in a vacuum oven. After battery assembling, galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) analyses will be applied to analyze the improvement of cycle-life retention, Coulombic efficiency, and impedance reduction attributed to titanium oxide-based additives. Besides, after charge/discharge cycling, the active materials will be characterized by field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). The results of this work will provide an innovative approach to improving the retention of SSBs by adding additives in iron oxides.