Esther S Takeuchi

Synthesis and Electrochemistry of Nanocrystalline Iron and Manganese Oxide Materials

In this presentation, novel low temperature, scalable methods will be discussed for preparation of two promising battery materials, magnetite and silver hollandite. Synthetic strategies for crystallographic control will be discussed, along with resulting impact of molecular architecture and composition on electrochemistry. This work will contribute to materials advances in the development of environmentally sustainable materials for new battery technologies.

SWNT Anchored with Carboxylated Polythiophene “Links” on High-Capacity Li-Ion Battery Anode Materials

Conjugated polymers possessing polar functionalities were shown to effectively anchor single-walled carbon nanotubes (SWNTs) to the surface of high-capacity anode materials and enable the formation of electrical networks. Specifically, poly[3-(potassium-4-butanoate) thiophene] (PPBT) served as a bridge between SWNT networks and various anode materials, including monodispersed Fe3O4 spheres (sFe3O4) and silicon nanoparticles (Si NPs). The PPBT π-conjugated backbone and carboxylate (COO-) substituted alkyl side chains, respectively, attracted the SWNT π-electron surface and chemically interacted with active material surface hydroxyl (-OH) species to form a carboxylate bond. Beneficially, this architecture effectively captured cracked/pulverized particles that typically form as a result of repeated active material volume changes that occur during charging and discharging. Thus, changes in electrode thickness were suppressed substantially, stable SEI layers were formed, electrode resistance was reduced, and enhanced electrode kinetics was observed. Together, these factors led to excellent electrochemical performance.

Final Technical Report on DE-SC00002460 [Bimetallic or trimetallic materials with structural metal centers based on Mn, Fe or V]

Bimetallic or trimetallic materials with structural metal centers based on Mn, Fe or V were investigated under this project. These metal centers are the focus of this research as they have high earth abundance and have each shown success as cathode materials in lithium batteries. Silver ion, Ag{sup +}, was initially selected as the displacement material as reduction of this center should result in increased conductivity as Ag{sup 0} metal particles are formed in-situ upon electrochemical reduction. The in-situ formation of metal nanoparticles upon electrochemical reduction has been previously noted, and more recently, we have investigated the resulting increase in conductivity. Layered materials as well as materials with tunnel or channel type structures were selected. Layered materials are of interest as they can provide 2-dimensional ion mobility. Tunnel or channel structures are also of interest as they provide a rigid framework that should remain stable over many discharge/charge cycles. We describe some examples of materials we have synthesized that demonstrate promising electrochemistry.

In-Situ Generation of Electrically Conductive Nanoparticles in Bimetallic Phosphate Materials for High Power Lithium Batteries

Polyanion compounds are receiving significant attention as materials for energy storage applications, most generally with compositions such as LixMyOz and LiwMxPyOz, where M = Fe, Mn, or V. Due to the opportunity to transfer multiple electrons per M formula unit, these materials can provide high capacities in lithium based electrochemical cells. Vanadium oxide based batteries have exhibited widespread utility for a variety of uses, including demanding specialty applications.(1) For example, silver vanadium oxide has dominated the implantable cardiac defibrillator market over the past 25+ years due to its high capacity, characteristic voltage curve, and high power output.(2, 3)