The Zaghib Group at Hydro-Québec has used in situ SEM to see SiOx particles grow and shrink during cycling. SiOx is a promising anode material for Li-ion batteries due to a high theoretical specific capacity of 1338 mAh/g and less volume change than Si upon charge-discharge. Analysis of the morphology changes in SiOx particles provides insight into the failure mode associated with capacity fade on cycling. [Read more…]
The Battaglia Group at LBNL has updated their standard operating procedures for making and testing lithium-ion batteries. The easy-to-follow SOP is publicly available at https://bestar.lbl.gov/vbattaglia/cell-analysis-tools/.
Designing Better Electrolyte Components for Lithium-Ion Batteries
Researchers at North Carolina State University are cooking up next-generation electrolytes for lithium-ion batteries, and their recipe calls for more salt. The Ionic Liquids and Electrolytes for Energy Technologies (ILEET) Laboratory, run by Professor Wesley Henderson, creates and characterizes new lithium salts and ionic liquids to formulate electrolytes with a wider range of operating temperatures and voltages. Electrolytes in current Li-ion batteries are limited by poor low temperature performance (< -10°C) and decompose at elevated temperatures (>55°C), potentially causing a fire hazard. To circumvent these issues, Henderson is developing new electrolyte components based on organoborates related to bis(oxalato)borate (BOB–) and cyanocarbanions. These anions are first synthesized as lithium salts, and then scaled up to form ionic liquids, which are salts that remain liquid even at room temperature or below and have low volatility.
Dr. Venkat Srinivasan, LBNL, delivered an informative overview entitled Present Research and Future Directions of the
Batteries for Advanced Transportation Technologies
(BATT) Program at the “Beyond Lithium-Ion” meeting at Oak Ridge National Laboratory, October 7, 2010.
Lithium Diffusion Pathways in Graphitic Carbon Anodes
Graphitic carbon is widely used as an anode material in lithium-ion batteries. For high-power applications such as hybrid electric vehicles, however, prolonged cycling at high rates can damage a graphite anode and lead to plating of lithium metal, thereby decreasing the lifetime and capacity of the battery. Elucidating lithium diffusion pathways in graphite provides insight into why these anodes are limited by modest charge/discharge rates. The Persson and Kostecki Groups, in collaboration with other BATT investigators, have quantified lithium-ion diffusivity as a function of transport direction in graphite anodes. Electrochemical experiments combined with first-principles calculations indicate that lithium diffusion in graphite is several orders of magnitude faster in the direction parallel, as opposed to perpendicular, to the graphene plane. These results provide guidelines for designing graphite anodes with preferential orientation for higher rate capability, which translates to faster charging batteries.