(692c) Importance of Conductivity and Structure in the Capactity Retention of NiO Anodes in Li Batteries

Over the past several years, there has been a considerable amount of effort put forth to increase the energy density of Li-ion batteries.  At the anode, transition metal oxides have emerged as one of the most promising classes of materials, offering multiple electron transfer steps per mol of reactant, acceptable electronic conductivity, and relatively low cost (though higher than traditional graphite materials).  Several mechanisms are active in this class of materials, with the most common being the conversion of the metal oxide to its base metal:

Charge: M_xO + 2Li⁺ + 2e^- -> xM + Li₂O

where M is the transition metal (Ni, Fe, etc).  Unfortunately, the reversibility of the conversion reaciton is not very good, leading to precipitous losses in the reversible capacity; sometimes almost all of the capacity can be lost in less than 20 cycles as material is trapped in the charged state. 

One of the most pressing questions in the literature for metal oxides is root cause for the poor reversibility. In this talk, we will discuss the roles of conductivity and initial metal oxide nanostructure on capacitiy retention, with NiO being a probing compound.  We will also summarize results that have allowed our group to produce high loading NiO-based electrodes that have reversible capacities around 700 mA/g, even after 100  cycles.