Thin Film and Solid State Batteries Is the future in R2R?

Transcription

1 Thin Film and Solid State Batteries Is the future in R2R? Nancy Dudney Andrew Westover, Andrew Kercher, Sergiy Kalnaus ORNL Erik Herbert, Michigan Technological Univ. Valentina Lacivita, Gerd Ceder LBNL ORNL is managed by UT-Battelle, LLC for the US Department of Energy Research sponsored by: ARPA-E IONICS program DOE EERE Office of Vehicle Technologies, BMR program ARPA-E IONICS program and DOE BES.

2 High expectations for solid-state Batteries Bosch press release Toyota Roadmap for solid state battery MIT and Samsung New superionic solid electrolyte based on bcc sulfur lattice 2

3 ORNL - DOE lab - solid state batteries for vehicles & grid Battery teams work closely; different parts of ORNL organization Always interested in finding industrial R&D partners Physical Sciences Directorate Energy & Environment Directorate Computing and Comp Sci Directorate Chemical Sciences Division Energy & Transport Sci Division Computation Sci & Eng Division 3 Phys Chem Materials Nancy Dudney dudneynj@ornl.gov Roll to Roll Manufacturing David Wood wooddl@ornl.gov Comp Energy & Energy Sci John Turner turnerja@ornl.gov

4 TFB pioneered ORNL, good performance small batteries 1988 began research, 1996 first licensed technology Key is electrolyte, Lipon, a lithium phosphorous oxynitride glass e - load 4

5 Operation is clean. A physicist s battery. Most electrode materials are same as bulk batteries. Others unique. Ion diffusivity is critical; also electronic transport in electrodes load e - current collector Li anode electrolyte LiCoO 2 cathode (101) current collector discharge charge Li + + e - Li Li + + e - Li discharge charge Li 1+x MO y Li x MO y + Li + + e - Li 1+x MO y Li x MO y + Li + + e - 5

6 Thin film batteries based on intercalation compounds See theoretical capacities Shape reflects the crystallographic phases of cathodes LiMn 1.5 Ni 0.5 O 4 is latest and greatest, best option for Co-free Reaction Li 0.5 CoO 2 LiCoO 2 Mn 1.5 Ni 0.5 O 4 Li Mn 1.5 Ni 0.5 O 4 Mn 2 O 4 LiMn 2 O 4 LiMn 2 O 4 Li 2 Mn 2 O 4 V 2 O 5 Li 2 V 2 O 5 1 µah = 3.5 mcoul 6

7 Exceptional cycling performance for thin film Li batteries Li Lipon Li x Mn 2 O 4 (550 C) Li Lipon Li x CoO 2 (800 C) Cell Potential (V) Li - LiMn 2 O 4 (2µm, 550 C) m A/cm 2 Initial Charge 10 to 500 µa/cm 2 D at 0.2 to 2 ma/cm Charge (µah/cm 2 ) Capacity (µah/cm 2 ) µa/cm µa/cm µa/cm µm LiCoO µm LiCoO Cycle V 25 C 7

8 Excellent cycling performance: LiNi 0.5 Mn 1.5 O 4 / Lipon / Li Same thin film cathode with solid Lipon electrolyte and liquid electrolyte Rapid fade typical of typical composite cathodes Conclude fade not due to spinel cathode 1 µm LMNO films V 25 C 5C cycling At 3.5V, ASR is about 200 ohm for TFB 8

9 Performance of thin film batteries demonstrates stability of Lipon electrolyte High energy & power density, rapid recharge (~20 min) High coulomb efficiency (~100%) and energy efficiency (~95%) Long cycle life and low capacity fade (1000 s of cycles) Stable cycling to >5V versus lithium Self discharge negligible (store for years) Can be solder bonded at 250 C. Operating temperature -25 to 100 C with some degradation Stable performance is attractive, but cost-effective manufacturing remains a challenge. 9

10 10 10 How TFBs are fabricated Li anode (thermal evaporation) Substrate Preparation Current collector (dc magnetron sputtering) Cathode (rf magnetron sputtering) Electrolyte (rf magnetron sputtering) Anode current collector (dc magnetron sputtering) Devil s in the details! Anneal cathode (optional, C) Anode current collector (dc magnetron sputtering) Protective coating A (parylene/ti) Here build on substrate. Other options to build on cathode, and build on electrolyte. Lithium-ion anode (magnetron sputtering)

11 Key is Lipon - sputtered dense metastable glass with N content Lipon Thin Film Electrolyte Properties (Amorphous Lithium Phosphorous Oxynitride) Lipon electrolyte film 11 Typical composition Li 3.3 PO 3.8 N 0.24 to Li 2.9 PO 2.9 N 0.7 Lithium conductivity 1-2 x 10-6 S/cm Electronic resistivity >10 14 Ω cm Lithium ionic transference number = 1 Stability window = 5.5 V vs. Li metal Stable in contact with lithium metal Stable to >300 C Near conformal, smooth surface, dense amorphous Elastic modulus 77 GPa Hardness 3.9 GPa Brittle, low fracture strength passivated or stable? Now also by ALD (Atomic Layer Deposition) University of Maryland & PneumatiCoat Technologies SEM cross-section of a Lipon film deposited on a polypropylene membrane.

12 Lipon stability with Li & high V cathodes questioned? Abundant experimental evidence - N in Li 3 PO 4 gives electrochem stability Important to understand adding N complicates processing Stability window (V vs Li metal) 0 1V 2V 5V Gerd Ceder s calculations suggest decomposition. Li 2 O + Li 3 P + Li 3 N at Li anode Li 2 PO 2 N + Li 4 P 2 O 7 or just Li 3 PO 4 at the cathode interface Possible passivation? 12 Richards, W. D.; Miara, L. J.; Wang, Y.; Kim, J. C.; Ceder, G. Interface Stability in Solid-State Batteries. Chem. Mater. 2016, 28 (1),

13 Model for Lipon shows role of N in structure & Li mobility. ab initio molecular dynamics No triply bonded N s N in structure as apical N and bridging 2 PO 3 groups Li mobility Most mobile by a bridging N. Least mobile at apical N. Models and experiment agree. Pub: Valentina Lacivita and Gerd Ceder 13

14 Recent models and experiments reveal details of Lipon structure not a typical glass Compositions with highest conductivity LiO 0.5 Experiment Models Agree: Neutron PDF FTIR So confident of structure Well separate from normal glass forming compositions with PO 2.5 network Li 3 PO 4 Usual N-bonding assignments do not fit with compositions PN 1.67 Lipon Doped Lipon Li 3 PO 4, no N 2 Li 4 P 2 O 7 glass forming LiPO 3 PO JACS 2018 V. Lacivita and A. Westover, et.al.

15 Recent models and experiments reveal details of Lipon structure not a typical glass Compositions with highest conductivity LiO 0.5 Experiment Models Agree: Neutron PDF FTIR So confident of structure Well separate from normal glass forming compositions with PO 2.5 network Li 3 PO 4 Usual N-bonding assignments do not fit with compositions PN 1.67 Lipon Doped Lipon Li 3 PO 4, no N 2 Li 4 P 2 O 7 glass forming LiPO 3 PO JACS 2018 V. Lacivita and A. Westover, et.al.

16 Recent models and experiments reveal details of Lipon structure not a typical glass Compositions with highest conductivity LiO 0.5 Experiment Models Agree: Neutron PDF FTIR So confident of structure Well separate from normal glass forming compositions with PO 2.5 network Li 3 PO 4 Usual N-bonding assignments do not fit with compositions PN 1.67 Lipon Doped Lipon Li 3 PO 4, no N 2 Li 4 P 2 O 7 glass forming LiPO 3 PO JACS 2018 V. Lacivita and A. Westover, et.al.

17 The ARPA-E IONICS challenge stabilize Li metal anodes for high energy vehicle/grid batteries using cost-effective solid electrolytes. Targets: 10 High current density Cycle almost all Li for deep cycle. 1 Extended cycle life High energy per area Albertus, (2018) Nat Energy SSB TFB with Lipon

18 No solid electrolyte (SE) can meet all performance metrics Each SE material is deficient Oxide ceramics and glass are brittle, hard to make thin, expensive, LLZO Li 7 La 3 Zr 2 O 12 doped LGPS Li 10 GeP 2 S Block co-polymers have lower conductivity and deform LGPS has poor stability with Li and is air sensitive What about composites of two SEs? Interface gets in the way of ion motion From IONICS arpa-e call for proposals, 2017, Paul Albertus

19 Short circuits occur when Li penetrates thru solid electrolyte Block copolymer (PS-PE)solid electrolyte in commercial batteries Operation at 60C Superionic conductor Lifetime depends on modulus, but is limited as SEEO gradually distorts, Li penetrates M. Singh,..., and M.P. Balsara, Macromolecules 40, 4578 ( 2007 ). 19 Ceramic electrolyte with garnet structure, doped Li7La3Zr2O12 Wide electrochemical stability Li deposits cause sudden shorts at higher current Lipon does not fail by shorts Cheng E. J., Sharafi A. and J. Sakamoto J., Electrochimica Acta (2016).

20 Because Lipon does not fail by shorts, our IONICS goals are: New compositions Lipon-like, more conductive than Lipon Practical processing low cost Assembly of cells with thick cathode best energy dense Test hypothesis. Lipon, and Lipon-like glasses, are better suited to stabilize Li anodes, than ceramic or polymeric electrolytes. Metastable and Glassy Ionic Conductors A MAGIC solid electrolyte. 20

21 What is reason that Lipon works? Composition (for passivation with Li and conductivity) Microstructure (boundary free) Flaw free surface (glassy smooth) Mechanical properties (high modulus, but some plasticity) Electronic resistivity Are Lipon-like powders be scalable, less expensive? Sufficient Li and N in glassy powder Reasonable conductivity as pressed compact, approaching sputtered films. Nice spray coat, How to sinter without crystallization? Rather expensive processing Lipon film 21

22 Cost target (ARPA-E) $5 per sq.m for electrolyte Sputter targets are expensive; assumed a more efficient design. Deposition assumed 100nm/m. Glassy powders formation capturing N also expensive, poor yield so far. Scale up & larger tools will improve efficiency Powder throughput Membrane from: powder sputtered 22

23 How do we get more energy from a solid state battery? seed Li protection lithium Lithium 23 Optimize materials volume and weight: Reduce inactive components Expand active electrodes 10x Balance electrode capacities electrolyte cathode substrate Typical battery, all a few micrometers cathode For high energy

24 24 New paths to Fabricate battery with very thick cathode 1.2 Cathode-supported battery 1.0 Rapid fabrication 0.8 to replace sputtering Pure, dense 0.6cathode or composite Apply thin 0.4 film current collector Maintain low 0.2 R interfaces 0.0 Li anode (thermal evaporation) Substrate Preparation Current collector (dc magnetron sputtering) Cathode (rf magnetron sputtering) Electrolyte (rf magnetron sputtering) Anode current collector (dc magnetron sputtering) Anneal cathode (optional, C) Anode current collector (dc magnetron sputtering) Protective coating A (parylene/ti) Critical Maintain good interfaces, adhesion Robust crack-free cycling Lithium-ion anode (magnetron sputtering)

25 What is maximum cathode thickness for good energy? Consider: Li & electron motion, mechanical integrity. Some free volume or disorder may relieve interface stress? Typical LiCoO 2 cathode film annealed 700 C to crystallize YI Jang, NJ Dudney,, J ES. 149 (2002) A Z. Wang, S Meng, NanoLetters 7 (2015)

26 Companies show ~15µm cathode can cycle as SS battery, LiCoO 2 cathodes have particularly high Li+ and electron transport. Sputtered cathodes Tape cast, sintered cathodes Dense, 120 µm thick does not cycle 26 Li + e - Wei Lai and Yet-Ming Chiang, Adv Eng Mat. (2010) 74% dense, thick cycles when wet by liquid electrolyte

27 Thick sintered cathodes require liquid electrolyte filled pores. Demonstrated by Yet-Ming Chiang s group 100 cycles with < 5% capacity fade Requires periodic replacement of the Li anode No binder or carbon Wei Lai and Yet-Ming Chiang, Adv Eng Mat. (2010) 27

28 How do we reduce excess Lithium? > % efficient 28 Traditionally, excess Li added because a little is lost each cycle. SE should stop this! Options All Li can come from cathode Need a copper current collector High purity Li OR use a thin Li layer as the current collector Can be very thin if protected seed Li protection lithium electrolyte cathode substrate Typical battery, all a few micrometers Lithium ~1/3 rd cathode thickness cathode For high energy

29 29 Fabrication of the Li anode Must grow on solid electrolyte Vacuum evaporation of Li UHV torr ~ 3 nm/s or more ~15 cm throw µm thick onto solid electrolyte Active interface is buried and protected Li anode (thermal evaporation) Substrate Preparation Current collector (dc magnetron sputtering) Cathode (rf magnetron sputtering) Electrolyte (rf magnetron sputtering) Anode current collector (dc magnetron sputtering) Anneal cathode (optional, C) Anode current collector (dc magnetron sputtering) Protective coating A (parylene/ti) 100 µm Lithium-ion anode (magnetron sputtering) Top surface will react without care to protect. tilted

30 Vacuum deposition conditions determine the grain size, film thickness, purity of the lithium and the interface. Vacuum evaporation dense films, equiaxed grains. (unliked rolled Li) Grain size, Li purity, determined by: deposition rate, base pressure, film thickness Surface reaction/passivation determined by base pressure and Ar glove box purity On clean solid electrolyte, Li coats entire surface with low interface resistance. Reflective Li films on glass Plans explore deposition conditions with new flexible deposition tool. 30 Coarse and fine grains of Li films cps thin Li full cps [110] [200] [211] [220] deg No strong texture found by XRD of Li films

31 Efficient cycling demonstrated with Li-free battery Upon charge Li from LiCoO 2 cathode is plated at anode No Li deposited, thin film of Cu current collector Extended cycling with little capacity loss. Protected overlayer is essential to prevent Li loss through Cu 3μm Li 31 Capacity (µah/cm 2 ) parylene + Ti overlayer Lipon overlayer no overlayer parylene overlayer (0.1 ma/cm 2 ) (0.1) Cycle (1.0 ma) (1.0) V 25 C 0 μm Li

32 Efficient cycling demonstrated with Li-free battery Upon charge Li from LiCoO 2 cathode is plated at anode No Li deposited, thin film of Cu current collector Extended cycling with little capacity loss. Protected overlayer is essential to prevent Li loss through Cu 3μm Li 32 Capacity (µah/cm 2 ) parylene + Ti overlayer Lipon overlayer no overlayer parylene overlayer (0.1 ma/cm 2 ) (0.1) Cycle (1.0 ma) (1.0) V 25 C 0 μm Li

33 Efficient cycling demonstrated with Li-free battery Side by side, Li-free battery matches battery with great Li excess Small initial loss would go unnoticed Cumulative loss over 1000 cycles would be obvious u 3μm Li 0 μm Li Solid lines = Li-free Dashed lines = Li battery 33

34 Good (indirect) evidence of low interface resistance for Lipon / Li Low area specific resistance (ASR), probably ~10 Ω for Li/Lipon, for TFB Buried interface is a clean interface; Li film is dense, coats irregular surfaces Z(real) (Ohm) Complex impedance cell at 3.93 and 3.0V Re Im Re Im partial discharge full discharge 25C; 2.0µm cathode Li/Lipon Lipon Z(imaginary) (Ohm) Cell Potential (V) µm thick LiCoO 2 / Lipon / Li cycled 0.02 to 1 ma/cm 2 ASR= ž cm Ω cmω 2 Current (µa/cm 2 ): 20, 100, 200, 500, 1000, and OCV 4 µm cathode Frequency (Hz) Charge (µah/cm 2 )

35 Assess elastic and plastic behavior of Li thin films As deposited then again with cycling Used nanoindentation housed in inert glove box. 3 Pubs by Erik Herbert J Mat Res (2018) Vol 33, issue 10 35

36 Assess elastic and plastic behavior of Li thin films As deposited then again with cycling Used nanoindentation housed in inert glove box. Fused Silica Berkovich indenter S=dP/dh loading unloading 3 Pubs by Erik Herbert J Mat Res (2018) Vol 33, issue 10 Hardness, the mean pressure the surface can support (flow stress) Elastic modulus 36

37 Mechanics tests For Li metal thin films on glass. Li metal is very ductile Unusual punch-in effect. Stochastic. Many indents mapped and analyzed for strain rate effects. Measured High strain rate Low strain rate 37

38 Pressure supported by the Li depends on the length scale Hardness, the mean pressure the surface can support (flow stress) 5 μm thick same nominal strain rates 18 μm thick 38 Erik Herbert J Mat Res (2018) Vol 33, issue 10 Yield strength of bulk polycrystalline Li is 0.5MPa Xu et al., PNAS (2017)

39 Li is harder than you think, and will crack solid electrolytes In small volume, dislocation glide is not active, so Li is quite hard. What is the implication for electrolyte failure? Li filled cracks will certainly grow and short!. L. Porz (2017) Adv Energy Mater 39

40 Energy dense solid batteries possible at different length scales 10 nm 1 µm 100 µm Long, Rolison Dudney, Cirigliano, Dunn Sehee Lee 40 For good energy density: active electrode materials must be thickest components anode - efficient cycling of lithium metal

41 Other R&D fabrication of solid state batteries 3D batteries - for higher interface area patterned electrodes, electrolyte by ALD to coat Trilayer tape cast ceramic electrolyte (Wachsman) Laminated electrode and electrolyte layers * Milled and pressed layers * * with softer materials * with softer materials 41

42 Summary What are the keys for battery? Different thicknesses for maximum energy density Implications for processing Requires multiple processing methods? Thick cathode transport limited Create hybrid adding liquid or gel electrolyte Good interfaces - conductive and stable Mechanical stability toward breathing of cathode and plating of lithium Cost effective and scalable manufacturing Clean, 100% contact, other factors TBD Mechanics of materials, defect formation and diffusion Material by material, subassemblies, full battery? Critical flaws may cause failure Low impurity, smooth surfaces. 42