Pankaj Alaboina – Seminar/Ph.D. Preliminary Defense, Monday, November 21, 2016 at 1:00 P.M.

JSNN – Pankaj Alaboina – Ph.D. Preliminary Thesis Defense/Monday Seminar

Candidate: Pankaj Alaboina

Advisor: Sungjin Cho, Ph.D.

Department: Nanoengineering

Date: Monday, November 21, 2016

Time: 1:00 P.M. – 3:00 P.M.

Location: JSNN Room 209

2907 E. Gate City Blvd., Greensboro, NC 27401

Title: “Prelithiated Si-Fe-Mn Alloy for High Energy Li-ion Batteries.”

Abstract:

Silicon anodes are the promising catch on the hunt for high-energy lithium-ion batteries. Even though graphite is the conventional and widely used anode material, but silicon (Si) has attracted great attention because of its natural abundance, non-toxicity, and very high theoretical specific capacity of nearly 4200 mAh/g (about ten times more capacity than graphite). However, Si suffers from tremendous volume changes (over 300%) during charge/discharge cycles and results in huge capacity fading over time, which is holding them to be implemented for commercial applications. The strains due to the huge volume changes cause pulverization of Si particles and eventually leads to electrode shattering and delamination, and adversely affecting the battery performance and cycle life.  One popular approach to overcome this issue is to fabricate Si with metal based alloys which can provide a super-elastic flexible metal matrix during the huge volume stresses to mechanically protect the Si and maintain the electrical integrities. In this work, Silicon-Iron-Manganese (Si-Fe-Mn) alloy combination was synthesized to deliver high cushioning effect during the Si massive volume expansions for long cycle life.  Si-Fe-Mn alloy (Si/Alloy) was produced using a low cost, low temperature, industry scalable, an easy synthesis that includes only mechanical milling. Si/Alloy battery electrodes prepared with the commercially equivalent high loading of ~ 2 mg/cm2 demonstrated excellent electrochemical cycle performance. Nevertheless, Si/Alloy particles were found to have mechanical crack defects generated by milling and provided a scope to improve its properties further. The approach was a low-temperature facile prelithiation of Si/Alloy material with inexpensive lithium stearate as an additive to allow its diffusion to prefill and fix the crack voids. Prelithiation of Si/Alloy increased the materials hardness improving physicochemical properties, reduced the surface area avoiding unnecessary lithium loss on surface defects (solid electrolyte interface reformations), and demonstrated enhanced battery cycle life.