New Electrode Materials and Electrolyte Solutions for Solutions for - PowerPoint PPT Presentation

New Electrode Materials and Electrolyte Solutions for Solutions for Rechargeable Li ion Batteries. Rechargeable Li ion batteries Doron Aurbach Elena Markevich Valentina Baranchugov Elad Pollak Gregory Salitra Ella Zinigrad Boris Markovsky Liraz Larosh Yossi Talyossef Maxim Koltypin Department of Chemistry, Bar-Ilan University, Ramat-Gan 52900, Israel

A scheme of a typical secondary battery Li-ion battery based on Li x C 6 /Li x CoO 2 electrochemistry LiPF 6 solutions in alkyl carbonates mixtures

Advances in rechargeable Li battery technology: � R&D of high voltage cathodes � R&D of new electrolyte solutions (better safety) � Pushing the capacity to high values � Nano materials/nano composites . � Maintaining a very high level of science: precise measurements using the most sophisticated techniques (SS NMR, Raman, FTIR, HR Microscopy, SPM, XRD, Neutron D, Sincherotron radiation for XANES, EXAFS, fine XRD, all the fine electrochemical techniques – SSCV, PITT, GITT, EIS, EQCM, in situ measurements) and high level ab initio calculations.

Pros Cons � High surface area – low � High surface area – high overall charge transfer reactivity. None of the resistance cathode/anode materials in Li batteries are intrinsically stable � Small size – small with the electrolyte diffusion length. Li solutions. intercalation processes may be controlled by SS � Small size – problems diffusion of Li ions in the host. Small diffusion of electrical contact and length – faster insertion electrical integrity of the active mass. Example: Nano vs. micro LiMn 1.5 Ni 0.5 O 4 spinel and LiMn 0.5 Ni 0.5 O 2 layered cathode materials.

0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 MCMB electrodes LiBOB ec:pc 2:3 LiBOB ec:pc 2:3 LiBOB ec:pc 2:3 LiBOB ec:pc 2:3 LiBOB ec:pc 2:3 LiBOB ec:pc 2:3 LiBOB ec:pc 2:3 LiBOB ec:pc 2:3 LiBOB ec:pc 2:3 LiBOB ec:pc 2:3 LiPF6 ec:pc 2:3 LiPF6 ec:pc 2:3 LiPF6 ec:pc 2:3 LiPF6 ec:pc 2:3 LiPF6 ec:pc 2:3 LiPF6 ec:pc 2:3 LiPF6 ec:pc 2:3 LiPF6 ec:pc 2:3 LiPF6 ec:pc 2:3 LiPF6 ec:pc 2:3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 1M LiBOB 1M LiBOB 1M 1M LiBOB/EC:PC 2:3 LiBOB/EC:PC 2:3 /EC:PC 2:3 /EC:PC 2:3 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 1 1 1 1 1 1 1 1 1 1 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 2 2 2 2 2 2 2 2 2 2 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 3 3 3 3 3 3 3 3 3 3 I (mA) I (mA) I (mA) I (mA) I (mA) I (mA) I (mA) I (mA) mA mA mA mA mA mA mA mA mA mA ( ( ( ( ( ( ( ( ( ( I I I I I I I I I I 1M LiPF 6 1M LiPF 6 /EC:PC 2:3 /EC:PC 2:3 1M LiPF 1M LiPF 6 /EC:PC 2:3 6 /EC:PC 2:3 a a a a -0.3 -0.3 -0.3 -0.3 -0.3 -0.3 -0.3 -0.3 -0.3 -0.3 b b b b Note the huge irreversible capacity in LiPF 6 solutions Note the huge irreversible capacity in LiPF 6 solutions Note the huge irreversible capacity in LiPF 6 solutions Note the huge irreversible capacity in LiPF 6 solutions Note the huge irreversible capacity in LiPF 6 solutions Note the huge irreversible capacity in LiPF 6 solutions -0.6 -0.6 -0.6 -0.6 -0.6 -0.6 -0.6 -0.6 -0.6 -0.6 Much better CV resolution Much better CV resolution Much better CV resolution Much better CV resolution Much better CV resolution Much better CV resolution and small irreversible and small irreversible and small irreversible and small irreversible and small irreversible and small irreversible capacity with LiBOB capacity with LiBOB capacity with LiBOB capacity with LiBOB capacity with LiBOB capacity with LiBOB solutions. solutions. solutions. solutions. solutions. solutions. -0.9 -0.9 -0.9 -0.9 -0.9 -0.9 -0.9 -0.9 -0.9 -0.9 -1.2 -1.2 -1.2 -1.2 -1.2 -1.2 -1.2 -1.2 -1.2 -1.2 V V V V V V V V V V Voltage (V vs Li/Li+) Voltage (V vs Li/Li+) Voltage (V vs Li/Li+) Voltage (V vs Li/Li+) Voltage (V vs Li/Li+) Voltage (V vs Li/Li+) The voltammetric behavoir of Li intercalation into MCMB graphite in 2 solutions. a- LiPF 6 EC:PC 2:3 b- LiBOB EC:PC 2:3

2.5 2.5 Synthetic graghite flakes 2 2 1.5 1.5 Voltage, V Voltage, V 1M LiClO 4 /EC:PC 2:3 1M LiClO 4 /EC:PC 2:3 1 1 1M LiClO4 1M LiClO4 0.5 0.5 1M LiBOB/EC:PC 2:3 1M LiBOB/EC:PC 2:3 1M LiBOB 1M LiBOB 0 0 0 0 250 250 500 500 750 750 1000 1000 1250 1250 1500 1500 1750 1750 2000 2000 2250 2250 2500 2500 Capacity, mAh/g Capacity, mAh/g The first and consecutive galvanostatic cycles of KS25 graphite electrode in LiBOB and LiClO 4 solutions.

LiPF 6 solutions + Li metal 0.5 W g -1 exo DSC curves of 1M LiPF 6 solutions in EC:DMC 1:1 and PC PC in the presence of Li metal at heating rate of 1°C min -1 EC:DMC 40 90 140 190 240 290 340 Temperature, °C LiBOB solutions + Li metal 2 W g -1 PC DSC curves of 1M LiBOB exo solutions in EC:DMC 1:1 and PC in the presence of Li metal at heating rate of 1°C min -1 EC:DMC Aurbach & Al, J. Power 40 90 140 190 240 290 340 Sources, (2007) in press Temperature, °C

Properties of Ionic Liquids, which make them promising Properties of Ionic Liquids, which make them promising electrolyte solution components for Li-ion and magnesium electrolyte solution components for Li-ion and magnesium batteries batteries � Liquidity over a wide temperature range � Non-volatility IL systems ensure very good safety features � Non-flammability � High thermal stability � High ionic conductivity ( over 10 -2 S cm -1 at r.t.) � Wide electrochemical window: the high anodic stability enables the use of a large variety of cathode materials in ionic liquid electrolytes, including materials which red-ox activity is around 5V vs. Li/Li + � Remarkable dissolution properties for organic as well as inorganic substrates, including Li and Mg salts. ▪ ILs are expected to be inert towards magnesium

Electrochemical windows of the imidazolium-based ionic liquids Electrochemical windows of the imidazolium-based ionic liquids 1.0 1.0 0.8 0.8 0.6 0.6 0.4 0.4 0.2 0.2 I, mA I, mA 0.0 0.0 0 1 2 3 4 5 6 0 1 2 3 4 5 6 7 -0.2 -0.2 -0.4 -0.4 -0.6 -0.6 -0.8 -0.8 Do not dissolve Li salts E, V E, V The cathodic limit of imidazolium 3.0 derivatives is relatively high 2.5 2.0 (about 1V vs. Li/Li + ). However, 1.5 they can be used in Li batteries 1.0 I, mA using passivation agents in 0.5 0.0 solutions. 0 1 2 3 4 5 6 -0.5 -1.0 -1.5 Dissolves Li salts E, V Working electrode: glassy carbon (0.2 cm 2 ), R.E.: Li/Li + , scan rate 20 mV/s, 25 0 C.

Electrochemical window of BMIBF 4 measured on glassy carbon electrode and insertion-deinsertion potential regions of LiCoO 2 and LiNi 0.5 Mn 1.5 O 4 cathode materials 2.0 2.0 250 250 250 4 4 4 4 4 4 CH 3 CH 3 CH 3 30 30 30 30 30 30 5-20 5-20 5-20 5-20 5-20 5-20 CH 3 CH 3 3 3 3 3 3 3 Capacity, mA h/g Capacity, mA h/g Capacity, mA h/g 200 200 200 1 1 1 1 1 1 1.5 1.5 N N N BF 4 BF 4 BF 4 E, V E, V E, V E, V E, V E, V 30 0 C 30 0 C 2 2 2 2 2 2 5-20 5-20 5-20 5-20 5-20 5-20 1 1 1 1 1 1 1 1 1 1 1 1 150 150 150 C 2 H 5 C 2 H 5 C 2 H 5 30 30 30 30 30 30 1 1 1 1 1 1 30 0 C 30 0 C 30 0 C 30 0 C 30 0 C 30 0 C BF 4 BF 4 N N 0 0 0 0 0 0 1.0 1.0 100 100 100 0 0 0 0 0 0 2 2 2 2 2 2 4 4 4 4 4 4 6 6 6 6 6 6 8 8 8 8 8 8 10 10 10 10 10 10 Time, hours Time, hours Time, hours Time, hours Time, hours Time, hours C/6 C/6 C/6 50 50 50 C/2 C/2 C/2 C 4 H 9 C 4 H 9 0.5 0.5 0 0 0 I, mA I, mA 0 0 0 20 20 20 40 40 40 60 60 60 80 80 80 Cycle number Cycle number Cycle number 0.0 0.0 0 0 1 1 2 2 3 3 4 4 5 5 6 6 -0.5 -0.5 LiNi 0.5 Mn 1.5 O 4 LiNi 0.5 Mn 1.5 O 4 LiCoO 2 LiCoO 2 -1.0 -1.0 -1.5 -1.5 E, V E, V One of the main advantages of room temperature ionic liquids – their high anodic stability - may be well exploited for the use of 5V LiNi 0.5 Mn 1.5 O 4 spinel cathodes. Aurbach, Markevich, Baranchugov , Electrochem. Comm.(2006)

Why silicon? 1. Very high capacity (> 4000 mAh/gr , better than that of Li metal). 2. Much better safety features, compared to Li metal. 3. Problems of co-intercalation of solvent molecules into carbonaceous materials do not exist with silicon.

Electrochemical window of the neat ionic liquid 1-methyl-1-propylpiperidinium bis(trifluoromethylsuphonil)imide, W.E. glassy carbon 0.8 20 mVs -1 , 25 0 C The 1 st anodic polarization on 0.6 freshly polished W.E. 0.4 The 2 nd canodic polarization 0.2 I, mA 0 -0.2 N(SO 2 CF 3 ) -0.4 2 The 1 st canodic polarization on N freshly polished W.E. -0.6 C 3 H 7 -0.8 -1 0 1 2 3 4 5 6 7 E, V A passivation process takes place during the cathodic polarization of MPPpTFSI solutions, even in the absence of Li salt . This passivation process enables the use of the additive free MPPpTFSI ionic liquid together with a Li salt, as an electrolyte solution for Li batteries. The cathodic peak, seen in the first CV cycle of the neat IL relates to the reduction of the anion.