Enhanced Low Temperature Performance Of Li-Ion Batteries Using Nanophase Materials
Abstract
One major problem that limits the rate capability at low temperatures of the current Li-ion batteries is the anode material, graphite. In order to overcome the limitations associated with graphite. new anode materials must be developed. One such potential new anode material that could lead to higher rates at the low temperatures required by the Future Army Combat and Force Warrior Systems is Li4Ti5O12 with a nanophase particle size. At present, no information on the rate capability at low temperature of nanophase Li4Ti5O12 is available. Hence, such information is needed. Two different nanophase Li4Ti5O12 particle sizes were investigated, 350 and 700 nm, over the temperature range 20, 0, -10, -20, and -30 C at low rates (0.1 C, C=theoretical capacity) to high rates (5C). Electrochemical testing revealed that the 350 nm Li4Ti5O12 material exhibited higher capacity compared to the 700 nm Li4Ti5O12 at all rates tested at room temperature and at low rates at low temperatures (< 0 C). This expected behavior is a result of the shorter diffusion lengths and higher number of lithium insertion sites in the smaller particle size material. This result also reveals the importance of reducing the Li4Ti5O12 particle size as small (i.e., from micron to nano) as possible for enhancing low temperature performance. However, at high rates at low temperatures (< 0 C) a change in behavior was observed, in that the larger particle size Li4Ti5O12 exhibited the higher capacity. It was observed that as the temperature was decreased the rate at which this transition occurred was also lowered. It is believed that the origin of this transition behavior is that as temperature is lowered the resistance of the Li4Ti5O12 interparticle contacts increases and controls the discharge rate. This result was unexpected and suggests that at low temperatures and high rates just reducing the Li4Ti5O12 particle size to the nanoscale is not enough to enhance low temperature performance.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 2006
- Accession Number
- ADA480998
Entities
People
- J. L. Allen
- J. Wolfenstine
- T. Richard Jow
Organizations
- United States Army Research Laboratory