STATO DI SVILUPPO DELL’ACCUMULO ENERGETICO PER VIA ELETTROCHIMICA LE BATTERIE AL LITIO Bruno Scrosati Laboratory for Advanced Batteries and Fuel CellTechnology LAB-FCT Dipartimento di ChimicaCentro Hydro-ECOSAPIENZA Università di Roma
Research background Wind Geothermal Cost of Oil (WTI) Solar Intermittent alternative energy sources (REPs) , as well as electric transportation, require convenient energy storage systems, e.g., batteries • Global warming : suppression of CO2 • Demand of oil in the world (particularly in BRICs) Energy Storage, Vehicle Kyoto protocol http://www-gio.nies.go.jp Courtesy of Dr. Ahiara, Samsung Research, Yokohama, Japan
Li-ionbattery system Electrochemical Reactions • Cathode • Anode • Overall Figure. Schematic illustration of a rechargeable lithium battery (From: K. Xu, Encyclopedia of Power Sources, Elsevier, 2010) 3
Charge Lithium-Ion Battery Electrolyte AL Current Collector Cu Current Collector Graphite LiMO2 SEI SEI
Discharge Lithium-Ion Battery Electrolyte AL Current Collector Cu Current Collector Graphite LiMO2 SEI SEI
Lithium Batteries Lithium batteries: high energy density (3 times lead-acid). Power sources of choice for the consumer electronics market The application of lithium batteries spans beyond the electronics market
HEV, EV and FCV in Japan Hybrid (HEV) and electric (EV) vehicles are already on the road HEV in market PHEV FCHV ? Their diffusion is expected to drammatically increase in the next few years EV Courtesy of Dr. Ahiara, Samsung Research, Yokohama, Japan Reference: Institute of Information Technology, Japan
Lithium Batteries Although lithium batteries are established commercial products further R&D is still required to improve their performance to meet the REP andHEV-EV requirement Enhancement in safety, energy density andcostare needed!
SAFETY Actions: Replacement of the oxygen releasing cathode material (LiCoO2) with structurally stable alternative compounds, e.g. LiFePO4 Replacement of the flammable liquid organic electrolyte with more stable materials, for example Polymer ionic conducting membranes
THE COST ISSUE Cost of lithium batteries in comparison with other rechargeable systems AVERAGE PRICE PER CELL IN 2005 Source : The rechargeable battery market, 2005-2015, June 2006 Source :TIAX, based on MEDI data
COST Actions: Replacement of the expensive cathode material (LiCoO2) with low cost, abundant alternative compounds, ideally iron or sulfur – based cathodes
Cost Comparison of various raw materials for lithium secondary batteries. Materials in use: LiCoO2 (cathode) ; Cu (current collector) Alternative materials: LiFePO4, LiMn2O4, S (cathode) ; Stainless Steel (current collector)
THE ENERGY ISSUE Energy Density (Wh/kg) driving range (km) Middle size car (about 1,100 kg) using presently available lithium batteries (150 Wh/kg) driving 250 km with a single charge 200 kg batteries Enhancement of about 2-3 times in energy density is needed!
Electric Vehicle Applications- The energy issue Revolutionary Technology-Change 500 km Battery Super- Battery < 200kg Pb-acid 3000 kg Ni-MH 1200 kg >500 Wh/kg 200 Wh/kg* Estimated limit of Lithium-Ion Technology 170 Wh/kg* 700 Kg 500 kg 140 Wh/kg* Li-ion Batteries Present 2012 2017 Year Courtesy of Dr. Stefano Passerini, Munster University, Germany
ENERGY DENSITY Actions: Replacement of the present electrode materials with alternative compounds having much higher values of specific capacity
High-Energy Battery Technologies X Where should we go? 500 km Battery 6 5 Potential vs. Li/Li+ 4 Oxide Cathodes High capacity cathodes "4V" 3 Li-ion Super- Battery <200kg/500km Li/O2 , Li/S 2 Intercalation materials 1 Carbon anodes "0V" High capacity 0 0 1250 250 500 1000 1500 1750 750 Capacity / Ah kg-1 Courtesy of Dr. Stefano Passerini, Munster University
Why Li/S battery? Anode Cathode e- e- Anodic rxn.: 2Li → 2Li+ + 2e- Cathodic rxn.: S + 2e - → S2- Overall rxn.: 2Li + S → Li2S, ΔG = - 439.084kJ/mol OCV: 2.23V Theoretical capacity : 1675mAh/g-sulfur Li+ + S Li+ Li+ Li+ Electrolyte (polymer or liquid) Li2S Li Future Li-S performance region Li-S, 2005 Sion Power Corp. Li-S, 2001 Prismatic Li-Polymer Prismatic Li-ion Cylindrical Li-ion SION POWER CORPORATION PBFC-2, Las Vegas, Nevada, USA, June 12-17, 2005 Ni/MH Ni/Cd Fig. Energy density comparison with commercial secondary batteries.
Why Li and S for electrode active material? (1) Lithium Sulfur -. Atomic weight: 32.06g/mol -. Light yellow solid (2.07g/cm3) -. Non-toxic, “green” material -. Abundant and cheap (28 US$/ton) -. Theoretical capacity: 1.675 Ah/g -. Atomic weight: 6.94g/mol -. Lightest alkali metal (0.54g/cm3) -. Silvery, metallic solid -. Theoretical capacity: 3.86Ah/g -. E = -3.045VSHE Courtesy of Prof. K.Kim, Gyeongsang National University, Korea http://periodic.lanl.gov
Why Li / S battery ? Comparison of various secondary batteries. Comparison of various raw materials for lithium secondary batteries. Courtesy of Prof. K.Kim, Gyeongsang National University, Korea
The lithium-sulfur battery The Li/S concept is not new. However, so far limited progress due to a series of practical issues Major Issues: solubility of the polysulphides LixSy in the electrolyte (loss of active mass low utilization of the sulphur cathode and in severe capacity decay upon cycling) low electronic conductivity of S , Li2S and intermediate Li-S products (low rate capability, isolated active material) Reactivity of the lithium metal anode (dendrite deposition, cell shorting, safety)
R&D is required to improve the performance of super-batteries, such as Li-S or Li-O2 to meet the HEV-EV requirement Large investments are in progress worldwide to reach this important goal .
Our approach: Total renewal of the battery chemistry, including all three components, i.e. anode, electrolyte and cathode. ANODE Conventional :Li metal our work : Sn-C nanocomposite (gain in reliability and in cycle life) ELECTROLYTE Conventional : liquid organic our work : gel-polymer membrane (gain in safety and cell fabrication) CATHODE Conventional : sulfur-carbon our work : C- Li2S composite Conventional : liquid organic (Li-metal-free battery ) (Li metal battery) Jusef Hassoun and Bruno Scrosati, Angew. Chem. Int. Ed. 2010, 49, 2371 http://www.wiley-vch.de/vch/journals/2002/press/201010press.html
THE BATTERY Specific advantages Control of lithium sulphide solubility (specifically designed polymer electrolyte) Easiness of fabrication (polymer configuration; match between anode and cathode specific capacity) Safety ( no lithium metal anode; no LiPF6 in the electrolyte; chemical stability of electrodes) Low cost ( abundant materials; simple preparation)
SnC nanocomposite / gel electrolyte/ Li2S-C cathodesulfur lithium-ion polymer battery High energy density (about 3 times that offered by common lithium ion batteries) and plastic design. Jusef Hassoun and Bruno Scrosati, Angew. Chem. Int. Ed. 2010, 49, 2371 http://www.wiley-vch.de/vch/journals/2002/press/201010press.html
Acknowledgement Funds Italian Ministry of Education , University and Resarch, MIUR , PRIN 2007 Project and SIID Project “REALIST” (Rechargeable, advanced, nano structured lithium batteries with high energy storage) sponsored by Italian Institute of Technology.