Electrochemical performance of lithium-rich layered oxides for

Transcription

1 IBA 2013 Electrochemical performance of lithium-rich layered oxides for electric vehicle applications Jay Hyok Song, Andrei Kapylou, Chang Wook Kim, Yong Chan You, and Sun Ho Kang* SAMSUNG SDI

2 Contents Samsung SDI and future LIB market Challenges in lithium-rich layered oxide Recent progresses - Fluorine added Li-rich layered oxide - Al doped Li-rich layered oxide Summary 2 /29

3 Samsung SDI Overview Foundation IT battery xev ESS (1970) (2000) (2008) (2010) CRT PDP AMOLED Mobile LIB xev ESS WW No. 1 WW No. 1 WW No. 1 WW No. 1 Major supplier to Industry Frontier ( 11 M/S : 31%) ( 11 M/S : 38%) ( 11 M/S : 98%) ( 12 M/S : 25%) global lautomakers (KW~MW line up) CRT PDP (42 to 60 ) AMOLED Lithium ion Battery (LIB) xev Battery Energy Storage System (kw~mw) Turnover ($B) /29

4 Global network Germany Russia Hungary India China Korea Japan USA Vietnam Taiwan Mexico Malaysia 9 Plants in 6 countries 3 R&D Centers Korea, Japan, Russia 8 Branches / Offices HQ in Giheung, Korea - Employees : 8500 (Korea) 9500 (Overseas) 4 /29

5 LIB market trend - Market Share (IT battery) - LIB market forecast WW No. 1 ( 12~) No SDI SDI 2 nd ~20% 23.2% B (23.5%) SDI 25.1% B (20.7%) xev ESS IT (51%) ($Bil.) (M) 800 1,000 1,250 (30%) (41%) * Techno systems research * Samsung SDI marketing team Advanced LIBs should be developed for increasing EV market 5 /29

6 LIBs for EV application Current state Under development Customer demand Distance 160 km (BMW i3) 200km 300km km 550km Energy density 125 Wh/kg 165 Wh/kg 230 Wh/kg >350 Wh/kg Power 3600 W 4300 W 5300 W - Cycle life (@80% EOL) 5000 cycle 5000 cycle 5000 cycle - Cathode 125mAh/g 150mAh/g 250mAh/g - Anode 350mAh/g 350mAh/g 650mAh/g - * Samsung SDI ABS team To realize 300km driving range, next generation cathode and anode materials should be developed. 6 /29

7 Cathode materials for LIBs Reversible Capacity (mah/g) Electrode Density (g/cc) Volumetric Capacity (mah/cc) Average Voltage (V vs. Li) Pros Cons LiCoO High density Li (Ni 1/3 Co 1/3 Mn 1/3 )O Low cost Rate LiMn 2 O performance, Low cost High thermal LiFePO stability, Low cost High cost, Degradation at high h SOC Degradation at high SOC Low capacity, Mn dissolution Low density Li 2 (Fe,Mn)SiO Potential for high capacity Low density, Low voltage Li 2MnO High capacity Li(Ni,Co,Mn)O 2 Poor cycle performance Among the cathode materials, Li-rich layered oxide can match the goals for 300km 7 /29

8 Li-rich layered oxide * M.M.Thackeray, S. H. Kang, et al., J. Mater. Chem (2007) Structure of Li-rich layered oxide LiMeO 2 region (Me = Ni, Co, Mn) LiMeO 2 region Li 2 MnO 3 region Li 2 MnO 3 region Nano-composite of LiMeO 2 -like and Li 2 MnO 3 -like phases One-third of Mn in transition metal layer of Li 2 MnO 3 is replaced with Li High theoretical capacity (>360mAh/g) due to excess Li ions in Li 2 MnO 3 -like phases Promising candidate cathode material for EV applications 8 /29

9 Li-rich layered oxide 4.5 LiMeO 2 -like Li 2 MnO 3 -like tage (V, vs Li) Vol NCM523 ( V) Li-rich ( V) Capacity (m Ah/g) * Li-rich comp. : Li[Li 1/6 Ni 1/6 Co 1/6 Mn 1/2 ]O 2 * Coin half room temp. Two step behavior during the first charge: LiMeO 2 -like region: LiMeO 2 Li + + MeO 2 + e - (Me = Ni, Co, Mn) Li 2 MnO 3 -like region: Li 2 MnO 3 2Li + + MnO 2 + 1/2O 2 + 2e - High capacity during the subsequent discharge * M.M.Thackeray, S. H. Kang, et al., J. Mater. Chem (2007) 9 /29

10 Challenges Cycle performance Capacity retention >92% after 300cycle Voltage depression V less than 0.03V after 300cycle High operating voltage > 4.5 V should be applied Rate performance >85% 3.00C/0.33C discharge capacity ratio Low density >2.6g/cc electrode density 10 /29

11 Case I : Fluorine added Li-rich layered cathode

12 Cycle performance Li-rich layered oxide showed significant decrease of capacity upon cycling 200 Piti Pristine * Li-rich comp. : Li[Li 1/6 Ni 1/6 Co 1/6 Mn 1/2 ]O 2 * Coin half room temp. LL:~ 5mg/cm 2 (mah/g) Capacity % 100 nm 300cycle 125 NCM111 ( V) Li-rich ( V) 0.1 µm Cycle (#) After cycling, fractures were created on the surface 10 nm * Measured by Samsung SDI analytical team Pristine We assumed that the fractures were originated from the oxygen loss during cycling 12 /29

13 Motivation for fluorine addition LiMe 3+ O 2 Me 4+ O 2 +Li + +e - * J.S. Kim, et al., Chem. Mater. (2004) Li 2 Mn 4+ O 3 Mn 4+ O * 3 + 2Li + + 2e - (Electrochemical process) Mn 4+ O * 4+ 3 Mn O 2 + 1/2O 2 (Chemical process) 4.5 Li 2Mn 4+ O 3 O 2- Voltage (V V, vs Li) O 2- O 2- O 2- Mn 4+ Li 2 Mn 3+ O 2 F O 2- O 2- O 2- F - F - Mn O 2- Capacity (mah/g) Lithium extraction is accompanied by electron removal from oxygen 2p band The unstable oxygen was released during cycling and caused structural instability If we modify Mn 4+ to Mn 3+, Mn could donate more electrons and suppress oxygen loss /29

14 SEM Image * Li[Li 1/6 Ni 1/6 Co 1/6 Mn 1/2 ]O 2-z F z z = 0.00 Starting materials (BET : 5.33 m 2 /g) z = 0.02 F source addition Mixing Heat treatment z = z = (BET : 4.23 m 2 /g) Sieving Fluorine addition tend to enlarge primary particles The larger the primary particles, the lower the performance, due to the longer distance 14 /29

15 Charge / discharge curves Discharge capacity was greatly increased with fluorine addition 0 * Li[Li 1/6 Ni 1/6 Co 1/6 Mn 1/2 ]O 2-z F z 4.5 * Coin half room temp V -100 Voltage (V V, vs Li) z= z = % dq Q/dV (mah/gv) Li 2 MnO 3 phase LiMeO 2 phase Voltage (V) 80% Capacity (mah/g) Based on dq/dv curves, more lithium ions were inserted into Li 2 MnO 3 -like phase during discharge process 15 /29

16 Cycle performance 225 * Li[Li 1/6 Ni 1/6 Co 1/6 Mn 1/2 ]O 2-z F z * Coin half room temp V 25V Discharge capacity (m mah/g) z = 0.00 z = 0.02 z = 0.05 z = % 89% Cycle (#) Cycle performance of Li-rich layered oxide was greatly improved with fluorine addition 16 /29

17 Li-rich layered cathode from other companies SDI SDI Company A Company B Company C (z = 0.00) (z = 0.05) (Hydroxide) (Carbonate) (Hydroxide) Discharge Capacity (@0.2C) 230 mah/g 245 mah/g 230 mah/g 250 mah/g 230mAh/g Ini. Effi. 82% 91% 82% 91% 80% Pallet density 2.6g/cc 2.6 g/cc 2.4 g/cc 2.3 g/cc 2.4g/cc Rate (@1.0C/0.1C) 80% 82% 81% 83% 70% Capacity retention (@40cycle) 89% 94% 90% 75% 80% Voltage depression (@40cycle) 0.07V07V 0.05V05V 0.13V 0.18V 011V 0.11V Samsung SDI s fluorine added Li-rich layered oxide showed best properties 17 /29

18 SIMS and XRD analyses 16 O 19 F 10 8 * Li[Li 1/6Ni 1/6Co 1/6Mn 1/2]O 2-zF z, Z= Li 55 Mn Intensity (co ounts/sec) O 19 F 7 Li 55 Mn Distance ( m) To define the position of fluorine, SIMS analysis was attempted Based on SIMS result, fluoride coating was not detected and fluorine ions are located in the particle * Li[Li 1/6 Ni 1/6 Co 1/6 Mn 1/2 ]O 2-z F z Composition Cell parameters a, Å c, Å c/a V, Å 3 z = (1) (3) (1) z = (1) (3) (1) z = (1) (4) (1) z = (1) (4) (1) XRD results indicated linear increase of c-axis parameter The increased c-axis can be related to improved rate performance 18 /29

19 XANES spectra XANES spectra showed that the Mn ions are partially reduced 0.65 * Li[Li 1/6 Ni 1/6 Co 1/6 Mn 1/2 ]O 2-z F z N ormalized absorption (a.u.) z= z=0.02 z=0.05 z=0.07 Mn K-edge Energy (ev) * Measured at Pohang Accelerator Laboratory (PAL) Fluorine substituted LiMeO 2 -Li 2 MnO 3 can de-intercalate lithium ions with less oxygen removal since reduced transition metals donate more electrons during lithium de-intercalation, leading to superior stability of the host lattice. 19 /29

20 Case II : Al-doped Li-rich layered oxide

21 Voltage depression *Li[Li 1/6 Ni 1/6 Co 1/6 Mn 1/2 ]O 2-z F z, Z= * cell with graphite anode, 1C cycling, V Pristine 100 cycle 200 cycle 300 cycle 400 cycle Pristine 100 cycle 200 cycle 300 cycle 400 cycle Spinel-like phase creation Li 2 MnO 3 2Li + + MnO 2 + 1/2O 2 2MnO 2 + Li + LiMn 2 O LiMn +Li + 2 O 4 Li 2 Mn 2 O 4 <2.8V reaction > * S.H. Park, et al., Mater. Chem. Phys. (2007) Voltage profile of Li-rich layered oxide changed due to spinel-like like phase creation upon cycling 21 /29

22 Motivation for doping Li 2 MnO 3 cycling Spinel phase transition Starting materials Cation source addition Mixing Heat treatment Doped Li 2 MnO 3 No phase change 3.65 cycling tage (V) Nominal volt Ref. Al Mg Zr Ti Cycle (#) Li 2 MnO 3 -like phase changed to spinel-like phase during cycling We assumed that cathion doping to Li 2 MnO 3 can suppress spinel creation However, doped Li-rich layered oxide showed no improvement 22 /29

23 Calculation on dopant sites Ab-initio calculation results * Calculated by SAIT 6 4 (ev) Formatio on energy Mg Al Mo Nb V Zn Ru La -6 Li (NCM) Ni Co Mn Li1 Li2 Mn LiMeO 2 Doping site Li 2 MnO 3 Ab-initio calculations showed that most cation preferentially located at Ni or Co site in LiMeO 2 -like phase One should use special doping method to insert dopant into Li 2 MnO 3 phase 23 /29

24 Acid treatment Volta age (V, vs Li) * Li[Li 1/6 Ni 1/6 Co 1/6 Mn 1/2 ]O 2-z F z, Z=0.05 * Coin half room temp V NCM-like phase Li MnO 3 like phase 4.25 Pristine 3.75 Acid treated Voltag ge (V, vs Li) Voltage (V, vs Li) Pristine NCM111 Acid treated NCM Capacity (mah/g) Pristine Li 2 MnO 3 Acid treated Li 2 MnO 3 Specific capacity (mah/g) Capacity (mah/g) After acid treatment, charge capacity of Li 2 MnO 3 -like phase was decreased Lithium ions in Li 2 MnO 3 -like phase might be preferentially extracted during acid treatment 24 /29

25 Experimental procedure LiMeO 2 Li 2 MnO 3 Active material donant Pristine Acid treatment H + H + H + H + H + Ion exchange H + H + Al doped H + ICP: Al/(Ni,Co,Mn) = Heat treatment Li1? Li2? Mn? 25 /29

26 Electrochemical properties * Coin half room temp V * Li[Li 1/6 Ni 1/6 Co 1/6 Mn 1/2 ]O 2-z F z, Z=0.05 * Coin half room temp V Voltage (V, vs Li) Ref. Acid only Acid + ion ecxhange Disch harge Capacit ty (mah/g) Ref. Acid only Acid+ion exchange Specific capacity (mah/g) Cycle (#) After Al ion exchange, the discharge capacity was slightly higher than pristine Al doped sample showed improved cycle performance 26 /29

27 dq/dv peaks 350 Ref. 350 Acid + ion exchange st 1C 40th 1C st 1C 40th 1C dq/dv 50 0 dq/dv Acid only 1st 1C 40th 1C Voltage (V) Voltage (V) * Li[Li 1/6 Ni 1/6 Co 1/6 Mn 1/2 ]O 2-z F z, Z=0.05 * Coin half room temp V 150 dq/dv Changes in Li 2 MnO 3 -like phase was suppressed Voltage (V) 27 /29

28 Voltage depression * Li[Li 1/6 Ni 1/6 Co 1/6 Mn 1/2 ]O 2-z F z, Z=0.05 * cell with graphite anode, 1C cycling, V 3.40 voltage (V V) Nominal Ref. Al doped Li-rich Cycle (#) Voltage depression of Li-rich layered cathode was clearly suppressed with Al doping 28 /29

29 Summary Challenges in Li-rich layered cathode should be overcome for commercial use. Cycle performance and voltage depression are most serious problem for cell maker. Fluorine addition on Li-rich layered cathode resulted in significant increase of capacity retention and initial efficiency. With fluorine, reduced transition metals donate more electrons during charging process, leading to less oxygen removal. Al doping was attempted to control voltage depression. The voltage depression was clearly suppressed after Al doping. The analysis of exact position of dopant in host lattice is under way. For commercial use, significant efforts should be made to improve electrochemical properties p of Li-rich layered oxide. 29 /29

30 Thank you! Contact information Sun Ho Kang ; sh0816.kang@samsung.com Jay Hyok Song; jayhyok.song@samsung.com