High Rate and High Capacity Li-Ion Electrodes for Vehicular Applications

Conference · Sun Jan 01 00:00:00 EST 2012

OSTI ID:1042521

Dillon, Anne C.

Significant advances in both energy density and rate capability for Li-ion batteries are necessary for implementation in electric vehicles. We have employed two different methods to improve the rate capability of high capacity electrodes. For example, we previously demonstrated that thin film high volume expansion MoO{sub 3} nanoparticle electrodes ({approx}2 {micro}m thick) have a stable capacity of {approx}630 mAh/g, at C/2 (charge/dicharge in 2 hours). By fabricating thicker conventional electrodes, an improved reversible capacity of {approx}1000 mAh/g is achieved, but the rate capability decreases. To achieve high-rate capability, we applied a thin Al{sub 2}O{sub 3} atomic layer deposition coating to enable the high volume expansion and prevent mechanical degradation. Also, we recently reported that a thin ALD Al{sub 2}O{sub 3} coating can enable natural graphite (NG) electrodes to exhibit remarkably durable cycling at 50 C. Additionally, Al{sub 2}O{sub 3} ALD films with a thickness of 2 to 4 {angstrom} have been shown to allow LiCoO{sub 2} to exhibit 89% capacity retention after 120 charge-discharge cycles performed up to 4.5 V vs. Li/Li{sup +}. Capacity fade at this high voltage is generally caused by oxidative decomposition of the electrolyte or cobalt dissolution. We have recently fabricated full cells of NG and LiCoO{sub 2} and coated both electrodes, one or the other electrode as well as neither electrode. In creating these full cells, we observed some surprising results that lead us to obtain a greater understanding of the ALD coatings. In a different approach we have employed carbon single-wall nanotubes (SWNTs) to synthesize binder-free, high-rate capability electrodes, with 95 wt.% active materials. In one case, Fe{sub 3}O{sub 4} nanorods are employed as the active storage anode material. Recently, we have also employed this method to demonstrate improved conductivity and highly improved rate capability for a LiNi{sub 0.4}Mn{sub 0.4}Co{sub 0.2}O{sub 2} cathode material. Raman spectroscopy was employed to understand how the SWNTs function as a highly flexible conductive additive.

• Research Organization: National Renewable Energy Lab. (NREL), Golden, CO (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: AC36-08GO28308
• OSTI ID: 1042521
• Report Number(s): NREL/AB-5900-84810; TRN: US201212%%807
• Resource Relation: Conference: Presented at the 243rd ACS National Meeting, 25-29 March 2012, San Diego, California; Related Information: Abstract No. FUEL-280
• Country of Publication: United States
• Language: English

Related Subjects

25 ENERGY STORAGE
77 NANOSCIENCE AND NANOTECHNOLOGY
ANODES
CAPACITY
CARBON
CATHODES
COATINGS
COBALT
DEPOSITION
DISSOLUTION
ELECTRODES
ELECTROLYTES
ENERGY DENSITY
GRAPHITE
IMPLEMENTATION
LITHIUM IONS
NANOTUBES
RAMAN SPECTROSCOPY
RETENTION
STORAGE
THICKNESS
THIN FILMS
Li-ion batteries
electric vehicles
high capacity electrodes