Upscaling battery technology

Transcription

1 Upscaling battery technology From material science to pack engineering Dr. Billy Wu Lecturer Electrochemical Science and Engineering group Imperial College London Dyson School of Design Engineering 1

2 The renewable revolution THE STONE AGE CAME TO AN END, NOT BECAUSE WE HAD A LACK OF STONES, AND THE OIL AGE WILL COME TO AN END NOT BECAUSE WE HAVE A LACK OF OIL. FORMER SAUDI OIL MINISTER, SHEIK AHMED ZAKI YAMANI Source: The Telegraph, June 25, 2000

3 Electrochemical Science and Eng. Lithium Ion Supercapacitors Solid State Redox flow batteries Load / Power generator Cerium Ti meshes 2 e - 2 e - 2Ce 4+ H + H2 C paper H 2 2Ce 3+ 2H + H 2 Pump Ion conductive membrane Crossover collector In-operando diagnostics Understanding degradation Improving performance Thermal & physical models Supercapacitors and lithium hybrid capacitors Hybridisation (batteries/fc) Understanding new tech. Modelling mechanical changes Thermal diagnostics Flexible batteries Novel chemistries Modelling Cell optimisation Electrode design Battery Pack Design Metal air batteries Fuel cells Techno-Economics Long Distances Heavy Vehicles Hydrogen & Fuel Cells Mass Market Plug-in-Hybrids Battery Electric Short Distances Light Vehicles Plug-in-Hybrids Advanced Biofuels Mass Market Note: Not to scale time Long Distances Heavy Vehicles Pack design BMS integration & control Thermal management Zinc-air batteries In-situ monitoring Electrolyte additives Scaffolds System design Control & safety Demonstration Integration challenges Market size & trends Business opportunities Investment decisions Supply chain value assessment

4 How do we make better batteries? Multi-length scale problem Cell design Pack design Electrode microstructure Selection of battery chemistry

5 Do we have good chemistry? Anode: High capacity and low voltage Cathode: High capacity and high voltage Electrolyte: Large stability window All: Cheap, mass produced, non-flammable

6 What s inside a battery Coin cell x-ray computed tomography. Video courtesy of Paul Shearing, UCL and Jeff Gelb, Xradia Lithiation-induced dilation mapping in a lithium-ion battery electrode by 3D x-ray microscopy and digital volume correlation. Eastwood et al. Advanced Energy Materials. Volume 4, Issue 4

7 In-operando x-ray tomography study of lithiation induced delamination of Si based anodes for lithium-ion batters. F. Tariq, V. Yufit, D. Eastwood, Y. Merla, M. Biton, B. Wu, Z. Chen, K. Freedman, G. Offer, E. Peled, P. Lee, D. Golodnitsky and N. Brandon. ECS Electrochemistry Letters 3 (7), A76-A Lithium-Silicon Batteries Lithium-silicon anodes - next generation battery electrodes Order of magnitude higher energy density (372 mah/g LiC 6 vs 4,200 mah/g Li 22 Si 5 ) Problem is volume expansion of 300% during lithiation causing failure In-situ x-ray imaging shows delamination process Electrolyte Li-Si Argon bubble Copper current collector XZ Segmented rendering: Yellow = Li-Si Pink = Cu Green = Li Li +

8 Zinc-air batteries Bare zinc tip before deposition Zinc Cycling Zn Zinc tip with dendrites emphasized Multi-scale in-operando x-ray tomography studies of dendrite formation in zinc-air batteries. V. Yufit, F. Tariq, D. S. Eastwood, B. Wu, M. Biton, P. D. Lee and N. P. Brandon. In preparation Zn 8

9 Novel manufacturing Flexible all-fibre electrospun supercapacitor. Liu et al. Submitted.

10 Battery technology readiness level Joint Centre for Energy Storage Research

11 Battery degradation Novel applications of differential thermal voltammetry as an in-depth state-of-health diagnosis method for lithium-ion batteries. Y. Merla, B. Wu, V. Yufit, N. Brandon, R. Martinez-Botas and G. Offer. Journal of Power Sources

12 Cell voltage / V Temperature change / K Model based control Physics based models can accelerate cell development times Model based control can also unlock powerful functionalities such as fast charging Increasing discharge rate Simulated / test data / 0.6 A (0.125 C) / 2.4 A (0.5 C) / 4.8 A (1.0 C) / 9.6 A (2.0 C) Capacity / Ah Experimental / Simulated (without entropy) / Simulated (with entropy) / / 1.2 A (0.25 C) / / 4.8 A (1 C) / / 9.6 A (2 C) Capacity / Ah Differential Thermal Voltammetry for tracking of degradation in lithium-ion batteries. B. Wu, V. Yufit, Y. Merla, R. Martinez-Botas, G. Offer and N. Brandon. Journal of Power Sources 173, Coupled thermal-electrochemical modelling of uneven heat generation in lithium-ion battery packs. B. Wu, V. Yufit, M. Marinescu, G. Offer, R. Martinez-Botas and N. Brandon. Journal of Power Sources 243,

13 Keeping cool Adapted Thermal image Hunt

14 -Z imag [m ] Thermal gradients HAMSTER CAGE Heat And Mass Transfer Experimental Rig for Controlled And Gauged Experiments Control panel with Lid Thermocouple terminal switches Banana sockets for electrical connection Battery compartment (A) Electrical equipment compartment (B) Coolant reservoir Radiator Adjustable feet Quick connector for water hoses Heating element holder Copper plate o C, isothermal 10 o C < T < 20 o C 5 o C < T < 25 o C 0 o C < T < 30 o C -5 o C < T < 35 o C Coolant in Coolant in 4 30 Hz increasing thermal gradient 5 Hz Coolant out Coolant out Hz Cell Hz Peltier Element Water cooled heat sink The effect of thermal gradients on the performance of lithium-ion batteries. Y. Troxler, B. Wu, M. Marinescu, V. Yufit, Y. Patel. A. Marquis, N. Brandon and G. Offer. Journal of Power Sources 247, Z [m ]

15 Better thermal management 6C discharge and 2C charge Tab cooling is better Instantaneous and lifetime capacity Surface Cooling Causes Accelerated Degradation Compared to Tab Cooling for Lithium-Ion Pouch Cells. Hunt et al. Journal of the Electrochemical Society. 2016, Vol 163. Pages A1846-A1852

16 Cost breakdown Cost increases the further up the value chain Majority of cost in a pack not always the batteries Many opportunities to reduce cost through better engineering 30% Cell cost breakdown Cell material costs 5% 8% 3% 12% 42% Cathode Anode Separator Electrolyte Cu foil Al foil Pack cost breakdown for 10 kwh PHEV Whole battery pack 2% 8% 20% 20% 20% 30% Cells Thermal management BMS Labour Logistics Other (inc. enclousres, harnessing) Johnson Matthey Battery Systems report

17 Battery packs contain 100s of cells Hundreds of cells can be connected in series and parallel Imperial Formula Student vehicle Ah Kokam lithium-polymer cells 2 sidepods with 252 cells each Each sidepod has 3 modules with 84 cells in a 12P7S configuration 9 kwh total capacity In-house built

18 Temperature / C Current / A Cell Strip Multiple cells, multiple problems Steel tie rods Plastic spacers Polypropylene mid plates Aluminium connector blocks A 10 A 11 A 12 A 13 A 14 A 15 A 16 A 17 A 18 A Cells 6 7 Polypropylene T and L pieces Insulating polyethylene plate Parallel Cell Number Non-uniform current loading Internal currents rebalance after load removal = 20 C Time / s Coupled thermal-electrochemical modelling of uneven heat generation in lithium-ion battery packs. B. Wu, V. Yufit, M. Marinescu, G. Offer, R. Martinez-Botas and N. Brandon. Journal of Power Sources 243, Module design and fault analysis in electric vehicle batteries. G. Offer, V. Yufit, D. Howey, B. Wu and N. Brandon. Journal of Power Sources

19 Cumulative Percentage / % Percent Percent Shifting the problem? ~93% of UK car trips are less than 25 km in distance The cost of a 300 km EV is high but a 25 km EV isn t Bigger batteries means lower utilisation Emissions can be worse for a coal fired grid Average Small Small/Medium Medium Large < 5 < 10 < 15 < 25 < 35 < 50 < 100 < < Day Distance Driven (banded) / miles All electric days possible / total days Electric miles possible / total miles Battery size / kwh Techno-economic and behavioural analysis of battery electric, hydrogen fuel cell and hybrid vehicles in a future sustainable road transport system in the UK. Offer et al. Energy Policy, 2011, Vol:39, pages: Environmental impacts of hybrid, plug-in hybrid, and battery electric vehicles what can we learn from life cycle assessment? A. Nordelöf et al, Int. J. Life Cycle Assess., 2014, 19,

20 The need for integration I b Current collector Single particle model of a lithium-ion battery Li Battery model Separator e - Li + Li + e - Li Current collector V b SoC C loss T bat To power converter model To network model P bat, SoC To energy loss calculation From battery model From power converter model From energy loss calculation SoC C loss T bat I PCC,RMS T j E loss Primary substation Key C01 Commercial/ industrial busbar C02 C03 C04 Apartment block busbar C05 C06 C07 C08 C09 C10 AB4 Network model Network topology AB05 C11 C13 YS BM KC RB AB06 AB07 BL C14 LL Residential network busbar Measured data C12 CC MR C15 AB01 FC C16 DG Point of connection of 100 kw 50 kwh ESS MA AB02 AB03 P, Q, V PCC To power converter model Power converter model From battery model V b V PCC I PCC θ I[n] = 2I PCC sin( 2π n n + θ ) V[n] = 2V PCC sin( 2π n n ) Power loss and temperature calculation N samples V n, I[n] I[n] V CE [n] E on [n] (1 + 2 V[n] V DC ) E[n] P cond [n] f sw P sw [n] P[n] N samples P[n] N 1 P[n] N n=1 P loss,avg I PCC,RMS T j To network model P, Q, V PCC From network model V[1] I[1] Converter Voltage - Current Sampling T1,D2 I[n] V[n] T2, D1 Conducting Devices V[N] I[N] T1 T2 D1 I D2 E off [n] T j V DC 600 An integrated approach for the analysis and control of grid connected energy storage systems. Patsios et al. Journal of Energy Storage. 2016, 5, I b P loss,avg To battery model To energy loss calculation

21 Are we there yet? Still fundamental challenges with new battery chemistries Lithium-silicon Volume expansion Metal-air batteries Reversibility Novel better! Innovations in manufacturing needed Eastwood Make better use of what we have already There are many causes of battery degradation Model based control can enable advanced functions such as fast charging Lots of room for better battery packs Need to understand thermal boundary conditions Better thermal management systems can prolong life and performance Multiple cells cause multiple problems Can t just shift the problems Decarbonisation of generation is needed

22 Thank you Dr. Billy Wu