能源材料-5

能源æ...

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Unformatted text preview: (Energy Materials) -5 Safety and reliability are always the concern • Increase of recall/end-user accident, observed at several applications such as P-DVD and DSC in addition to NBPC/Cellular. • Cause: Electrolyte leakage by bad sealing part design and manufacturing trouble in the past, currently cell internal short by the contamination or insufficient control of particle. • Number of LIB cell-pack accidents is : LIB annual shipment (Billion cells) Recall/End-user side Cell maker/OEM LIB shipment Number of accidents Note) Number of accidents: Counting 1 example as 1 accident Ex: Nikon’s DSC LIB battery pack recall is 1 accident (announced on 2005/11/9, Objective packs 710K, accidents reported 4 abnormal heating) Copyright ©2006 /IIT Page 4 • • • • Keep the Balance 2006(3000 mAh) Non-flammable Solvent Polymer LiMn2O4 Alloy New Anode Binder additives 2003 1997 1991 Year (2400 mAh) LiNiCoO2 LiFePO4 3-layered MCMB Separator Graphite (1700 mAh)Anode Thin (1000 mAh) LiCoO2 Separator Thin collector Safety Energy Density General battery Heat dissipation rate Heat generation rate High energy battery Heat generation rate Heat dissipation rate To, ambient T1, Ignition point T2, Temperature Fire point To, ambient T1, T2 Ignition & Fire point Temperature Method: decrease heat generation rate & increase heat dissipation rate • Thermal Runaway Mechanism: ---the heat generation and dissipation are related to the volume an d surface area of the cell, respectively, the heat generation surpasses the heat dissipation as the cell size increases. Temperature Reaction 90~120 SEI decomposition (LiC6/Electrolyte reaction) 170~230 LixCoO2 decomposition 250~300 LiC6/PVDF reaction >300 combustion • The exothermic reactions for cell: (1)The chemical reduction of the electrolyte by the anode (2)The thermal decomposition of the electrolyte (3)The oxidation of the electrolyte on the Cathode (4)The thermal decomposition of the anode (5)The thermal decomposition of binder for coated electrodes (6)The thermal decomposition of the cathode LixC6 collapse LixMO2/Decomposition + Reaction with Electrolyte, M= Ni, Co, Mn (150J/g) Solvent + LiPF6 (250J/g) Heat generation Separator Fusion (PE) (-190J/g) LixC6/electrolyte 80~120 150 170 220 240 350 Temperature Method: develop high capacity and low enthalpy electrode material (1)-Overall Thermal runaway Anode: SEI decomposition Graphite (-76 J/g, 80~120 ) Secondary SEI formation (-624 J/g ) LiC6 collapses (-2400 J/g, 220~300 ) Li react with PVDF LiF and H2 Separator: PE Separator Fusion (130~150 ) Heat Energy Balance Equation of Battery Input+Gen.-Consumption=Accumulation Cathode: Li0.53(Ni0.8Co0.15Al0.05)O2 LixMO2 collapses (>220 ) LixMO2 react with PVDF -470 J/g (340~350 ) LixMO2 react with solvent (-725 J/g, 210~270 ) LiPF6 decomposition (endothermic, >240 ) (2)-Cathode Li0.53(Ni0.8Co0.15Al0.05)O2 LiMO2 O2 O2 1/2 Li2O + 1/x MxO + (1/2-2/x)O2 (1050J/g) (380J/g) Ethylene carbonate (EC) : -1166 kJ/mol (13.25 kJ/g) Ref. (3) -Oxide EC DSC Li0.53(Ni0.8Co0.15Al0.05)O2*1[Doping] DEC EMC PC LiPF6 PVDF Carbon Onset T 1 2 3 (J/g) 100 235 N.A. LiPF6 , EC>PC~EMC>DEC EC~1166 kJ/mol PVDF MCL Cathode M a teria ls ( J /g ) L i 0 .4 9 C o O 2 L i 0 .3 6 N i 0 .8 C o 0 .2 O 2 L i 0 .3 6 N i 0 .8 C o 0 .2 O 2 ( M g O ) [C o a tin g ] L i 0 .5 3 (N i 0 .8 C o 0 .1 5 A l 0 .0 5 )O 2 * 1 [D o p in g ] R ef1 : 120 350 ( DSC 1 ) ( ---305 ) 213 207 2 ( ---325 ) 3 < 1 0 0 (7 9 ) 2 1 0 380 286 Cycle Test of High-Capacity Slim Li Battery-2 LiCoNi 383450 560 cycles 1.0C Charge and Discharge 4.4 4.2 4 3.8 • 383450 ALB cell(3.8 x 34 x50mm) Voltage (volt) 3.6 3.4 3.2 3 2.8 2.6 0 100 200 300 400 500 Capacity (mAh) 600 700 Item s 500th 800 1st 900 R es ults PA S S F igur es LiCoNi 383450 560 cycles 1.0C Discharge cycle life and Capacity Capacity (mAh) Sample: No. 13 Tes t Co nd it io ns InternaU resistance: 24.8 mLo ad CR l SH 13K N Temp.: RT Loss: (P EN ETA28.2)N 7873m m00%N ail 787 N 6IAT IO / -RL * 1 S .S . = 20.18% O V ER C H A R G E 1C 12V O verc harge PA S S PA S S Cycle life Comparison of Li0.33Ni1-xCoxO2 with MgO-coated Li0.33Ni1-xCoxO2 450 C o In-situ Time-resolved XRD data 220 Fm3m 450 C o 111 200 220 Spinel Ni2O3 240 oC 240 oC 25 C o R-3m 10 002 Graphite 15 20 25 oC R-3m 10 002 Graphite 15 20 003 113 110 108 102 101 105 104 003 107 113 110 108 Uncoated Li0.33Ni1-xCoxO2 102 101 25 105 104 30 107 35 40 MgO-coated Li0.33Ni1-xCoxO2 25 30 35 40 Much slow decomposition benefited from MgO coating Comparison of Li0.33Ni1-xCoxO2 with/without MgO coating (100%SOC) 450oC In-situ Time-resolved XRD data (220) spinel 395oC Ni2O3 245oC 102 101 graphite 225oC 20 Uncoated Li0.33Ni1-xCoxO2 25 30 35 40 MgO-coated Li0.33Ni1-xCoxO2 Ni2O3 phase was not observed for the MgO coated sample. 15 20 25 DSC heat flow test: 15 DSC LiNiCo(M )O2 Heat flow(-W/g) 10 LiNiCoO2 LiCoO2 350 J/g 5 100 J/g 0 -5 150 175 200 225 Journal of The Electrochemical Society , 149 A743-A747 2002 250 Temperature(C) Pressure Profile of the Cathode in Comparison with DSC Profiles oxygen generation cathode/separat or/electrolyte cathode/separator cathode gas from cathode 29. Journal of The Electrochemical Society, 153 (11) A2166 -A2170 (2006) DSC at 10 /min on fully lithiated graphite electrode (a) without electrolyte after rinsing-dotted line, (b) with electrolyte full line Impedance Spectroscopic Characterization of Polymer Lithium-ion Battery at Elevated Temperatures in Accelerated Rate Calorimeter(ARC) Tested cell Tested cell UP343456 Polymer Li-ion 3×33×48 500 11.2 LiCoO2 MCMB-based PC-EC-LiPF6-PVDF Polyethylene Table 1. Sample of prismatic polymer lithium -ion cell for thermal runaway tests and electrochemical impedance spectroscopy. Sony Type Dimensions (mm) (thickness×width×length) Capacity (mAh) Weight (g) Cathode material Anode material Electrolyte Separator Experimental Einxperimental Thermal runaway tests ARC Thermal Electrometer (Keithley 610C) Milliohmmeter (Hewlet Packard 4338B) ARC(accelerated rate calorimeter) 2000TM (Columbia Scientific Industries) Top Heater Ice Point Reference Figure 1 Schematic diagram of the ARC set -up. Impedance (at 1kHz) : Milliohmmeter(Hewlet Packard 4338B) (Internal resistance R 2 Open circuit voltage(OCV) : Electrometer ( Keithley 610C) Side Heater Side Heater Bottom Heater Thermocouple ARC Controller Cell X) 2 Heat-Wait-Search mode Heat-Wait-Search mode 200 180 Cell temperature dT/dt > 0.05 Exothermic reaction C/min Cell temperature ARC cavity temperature Temperature / C O 160 140 120 100 20 The ARC cavity temperature was increased by 5 C. 22 24 26 28 time / hr 30 32 Figure 2 Process of Heat-Wait-Search mode in thermal runaway experiments. Thermal behavior Thermal behavior1 (b) SOC=25% (a) SOC=0% (a) 200 Temperature / C 180 160 140 120 100 20 25 Cell temperature ARC cavity temperature 30 35 time / hr 40 45 155 C O 20 25 30 time / hr 35 40 Figure 3 Thermal behavior of the cell during thermal runaway tes ting (SOC=0, 25 %). Thermal behavior Thermal behavior2 (b) SOC=100% (a) SOC=75% (a) 200 Temperature / C 180 160 140 120 100 20 22 24 Cell temperature ARC cavity temperature 26 28 time / hr 30 151 C O 138 C 32 15 20 time / hr 25 30 Figure 4 Thermal behavior of the cell during thermal runaway tes ting (SOC=75, 100 %). The internal resistance and OCV of the cell Open circuit voltage / V The internal resistance and OCV of SOC=0% SOC=25% cell the 10 5 SOC=75% 2 Internal resistance / 4 3 2 1 0 SOC=100% 10 10 10 10 1 Separator Shutdown 0 -1 -2 100 110 120 130 140 150 160 O Temperature / C 100 110 120 130 140 150 160 O Temperature / C Figure 5 The internal resistance and OCV profile of the cell as function of temperature (SOC=0, 25, 75, 100 %). Separator Shutdown Separator Separator Shutdown Li+ Li+ Li+ Li+ Li + Figure 6 Schematic representation of shutdown separator. Experimental Experimental In situ ac Impedance measurements as function of temperature Potentiostat (Solartron,1286 Electrochemical interface) Side Heater Top Heater Temperature rises in ARC Side Heater After 1 hour Electrochemical impedance spectroscopy Frequency : 10kHz~100mHz (5minutes) Amplitude of AC signal : 10mV-rms Voltage : open circuit voltage Cell FRA (Solartron,1260 Frequency response analyzer) Bottom Heater Thermocouple Ice Point Reference ARC Controller Figure 7 Schematic diagram of the ARC set -up. Temperature profile Temperature profile 140 120 Impedance measurement 125 110 100 C C 120 C C 130 C Temperature / C O 100 80 60 40 20 0 0 2 4 6 time / hr 8 10 12 25 50 C 75 C Cell temperature ARC cavity temperature C Figure 8 Temperature profile during impedance experiments. Before の After SOC=0% SOC=25% SOC=75% SOC=100% Figure 18 Pictures of lithium-ion battery before and after in situ ac Impedance measurements. Functional Electrolyte (I) Mechanism: Stable SEI formation on anode surface by adding 1-5 % of vinylene carbonate or propane sulton Effect: Improvement of cycle life, storage stability (especially under high temp.), swelling prevention Functional Electrolyte (II) Mechanism: Additive agent which has hydrogen atom bonded to tertiary carbon atom is Electrochemically active and generates H2 gas at 4.5 V Effect: overcharging H2 gas evolution pressure increase CID operation disconnection of cell circuit TRI-001 TRI-311 TRI-013 without TRI with TRI-013 with TRI-311 1 M LiPF6 in EC-DMC(1:1) With 5 wt.% TRI-311 With 5 wt.% TRI-013 With 5 wt.% TRI-001 15.3 4.9 7.2 5.7 5.1 4.2 1.2 2.5 213 220 210 200 248 280 203 263 Fig. 2. Thermal behavior of electrolytes containing a strip of l ithium in 1M LiPF6, EC-DMC, 5 wt.% TRI-013 or 5 wt.% TRI-311. 1 M LiPF6 in EC-DMC(1:1) With 5 wt.% TRI-311 With 5 wt.% TRI-013 With 5 wt.% TRI-001 177 203 300 240 without TRI with TRI-001 J. of Power Sources, 161 (2006) 1341. 1 Additives for Stabilizing LiPF6-Base Electrolytes Against Thermal Decomposition DEC DMC EC LiPF6 A 1.0 M solution of LiPF6 in EC/DEC/EMC mixed by weight 1/1/1 (standard electrolyte) pyridine HMOPA[1] HMPA[2] Addition of low concentrations (3-12 %) pyridine: PF5 complex [1] hexamethoxycyclotriphosphazene, [N=P(OCH3)2]3 [2] hexamethylphosphoramide, (C2H6N)3OP NMR Cell performance HMPA: PF5 complex 1 M LiPF6 in 1:1:1 EC/DEC/EMC (1/1/1) 3 % pyridine 10 % HOMPA 3 % HMOPA 12 % HMPA EMC is believed to occur from the rearrangement of DMC and DEC via a PF 5 or OPF3 catalyzed transesterification, and EC is kinetically more stable at elevated temperature than DEC, DMC, or EMC. 8000 9000 J. of Electrochem. Soc., 152 (2005) A1361. Overcharge Reaction of Lithium-ion Batteries Voltage and Temperature Change at Overcharge Gas Evolution at the Cathode and Anode Voltage Temp. Fig. 3. Gas composition of the H-shaped glass cell overcharged at 3 mA cm−2. Fig.2. Gas evolution characteristics of 633048- type prismatic cells at a 1 C rate overcharge. J. of Power Sources, 146, (2005) 97. Battery situation Safety protection V 4.5 Unsafety region 4.25 Degradation of performance 4.1 Actual usage region PTC(positive temp. coefficient) PE separator Gas release vent PCB(protection circuit board) *overcharge, over discharge, over- current protection Controlled by charger PP/PE/PP Al Al2O3 layer Anode layer (Graphite) Cu foil Anode layer (Graphite) Al2O3 layer PE layer Cathode layer(LiNiCoO2) Al foil Cathode layer(LiNiCoO2) Al2O3 layer PE layer 3 F u tu re L iN A iC o O A h 2 2 2006 L iN iC o O A h 2 1 M BI L iC o O C a rb o n 2400m 3 .7 V h /L 525W 4 .2 V 3 .0 V h /L A h 2 l l o -y b a s e d 3600m 3 .4 0 V 740W 4 .2 V 2 .0 V h /L C a rb o n 2900m 3 .6 V 620W 4 .2 V 2 .5 V • • • • • • • / • OCV • IR : (lithium dendrite) (C)Thermal Runaway Energy Storage Device Testing Platform •Power safety design for system products. Safety •Battery and Pack safety (UL,IEC,CNS) verification, Approved Accelerated & Reliability Test. •Battery FMEA analysis (failure mode/ effects/ mechanism analysis). •Material safety evaluation, ion transfer/electrode interface control and verification. UL/IEC/CNS Material, Battery and Power System Testing & Verification Platform System Makers Pack Makers Energy Storage Device Makers High Safety & Low Enthalpy Materials Material& Components Makers High Capacity & High Power Balance Taiwan Power Makers Energy Storage Device Testing & Verification Platform PT: LIB penetrates as scheduled • 1) Confirm reliability by 1-4S products (03-05CY). • 2) Create new products with 28-36V pack (05-09CY), replacing some ACpowered and Air-types. • 3) After lowering cell cost, replace NiCd for main stream 12-18V (08-12CY). • Notable technology is B&D/A123’s LiFePO4 type. • PT pack voltage trend and rechargeable battery user share (06CY). Panasonic 3% Copyright ©2006 /IIT Page 46 PT: Is it safe enough? • Pack configuration and safety features really vary by designers • No FET for over-charge, No Current Monitor…Every pack may have excessive current by external short • Design comparison of LIB pack/charger of PT: Makita BL-1430 14.4V 3.0Ah Sony 18650V 4S2P Charge method Pulse max 3C Max 4.05V/cell Thermal control Yes Cooling fan Yes Pack Charge Voltage Monitor By Micro-C(4 cell total V) Discharge Voltage Monitor No Charge Current Monitor No(PTC inserted) Discharge Current Monitor No ID By Micro-C Mode Over-chage state Cut charger Over-discharge state No control Short circuit Excessive current Hitachi Ryobi Bosch EBM-1430R B-1425L IXO 14.4V 3.0Ah 14.4V 2.5Ah 3.6V 1.0Ah Sanyo 18650W 4S2P Sony 18650VT 4S2P Sony 18650VT 1S CC-CV max 2.6C CC-CV max 1.8C CC max 0.4C Max 4.20V/cell Max 4.095V/cell Max 4.10V/cell Yes No No Yes No No By IC(1 cell each) No By Discrete parts circuit By IC(1 cell each) No By Discrete parts circuit No(Fuse inserted) No(Thermal protector 7A) No No No(Fuse 40A) No No By Hole IC Cut charger No control Cut charger FET off No control FET off (at 1.5V) Excessive current Excessive current No possibility Ryobi pack inside/circuit block Copyright ©2006 /IIT Page 47 • • : :UL1642, UL2054, IEC61960-1, IEC61960-2, CNS 14856, CNS 14857 ,,3C * Electrical Tests Short-Circuit(UL) Abnormal Charge(UL) Abusive Charge(UL) Forced Discharge(UL) Limited Power Source(UL) Crush(IEC/UL) Impact(IEC/UL) Shock(UL) Vibration (UL) 250 N Crush(UL) Mold Stress Relief(IEC/UL) Drop Impact(IEC/UL) Projectile(UL) Heating (IEC/UL) Temperature Cycling(IEC/UL) (IEC/UL) At room temp At 60℃ Mechanical Tests Battery Enclosure Tests Fire Exposure Tests Environmental Tests 5 5 5 5 5 3 5 5 5 5 3 3 3 5 5 5 5 5 5 5 5 5 5 5 5 5 3 3 3 5 5 5 5 “* ” 25% 90 • • , , , • • • • • ...
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