STORAGENERGY TECHNOLOGIES INC — Department of Energy SBIR Phase I: 13a

Description

Si has been considered as a potential candidate to replace the current anode material, graphite (372 mAh/g, LiC6), because of its high capacity (3579 mAh/g, Li15Si4), low environmental impacts, and potentially low cost. However, the utilization of Si in LIBs has been hindered by two major issues: 1) Si particles experience huge volume expansion up to 300%, which causes mechanical disintegration of the electrodes; 2) sophisticated interaction between the organic carbonate electrolytes and Si particles results in the formation of unstable SEIs on the Si surface. The unstable SEI and the newly formed interface induced by repeated volumetric expansion/contraction lead to the continuous formation of SEIs, which makes the electrode more insulated and leads to low Coulombic efficiency (CE). One approach to address the unstable (non-passivating) SEI layer on silicon is the development of an artificial SEI, which can enhance the ionic and electric conductivity, accommodate volumetric changes, prevent particle agglomeration, and modify surface conditions favoring a robust interface. This functional artificial SEI can overcome the science and technology barriers to the use of silicon-based anodes in high-energy density LIBs for transportation applications. In addition, achieving stable cycle life of Si anodes in the high-energy full cell is another tough challenge in that the capacity fading of Si anodes is pronounced in the full cells rather than in the half cells. In full cell configuration, the irreversible capacity is associated with the active material loss, whereas the reversible capacity loss is associated with side reactions. Storagenergy Technologies Inc. (Storagenergy) and Virginia Tech. (VT) propose to develop stable artificial SEI on Si anode by MLD process and an in-situ pre-lithiation method for high energy density and long cycling life LIB development. The artificial hybrid SEI on high-capacity Si anode will improve the mechanical/chemical properties and protect the Si surface from the attack of reductive electrolytes. The in-situ pre-lithiation method will significantly simplify the conventional pre-lithiation process to compensate the lithium loss during the initial electrochemical cycle.Our high-performance LIBs system with highly mechanical stability and chemically stability Si anode and in-situ pre-lithiation technology promise to transform the energy storage and distribution fields. This technology, in the distributed energy storage form, reduces greenhouse emissions by serving as a gateway technology to the widespread use of alternative and more importantly intermittent energy sources, namely wind and solar. The distributed Si anode-based LIB technology will also serve a critical need in the future Smart Grid by moderating the daily fluctuations in the power grid. And, finally, this technology will serve to re-establish the U.S. technological lead in batteries that has migrated overseas. The successful development of this technology will enable a new family of American batteries of all scales for both commercial and government sectors.