l11: batteries mechanical and electrical layouts · l11: batteries mechanical and electrical...

L11: Batteries Mechanical and Electrical Layouts

L11: 16-APR-2019

Lund University / LTH / IEA / AR / MVKF25 / 2019-04-16 2

Outlook

• Modules and modularity– Electric connections

– Ø18L650 battery back – Web tutorials

• Cells and technologies– Cylindrical, prismatic, Pouch – heat flow in cell

• Packs, Banks and packing topologies– Cooling integration

• Battery pack design


Electric connection of cells

• Series [V] –parallel [Ah]connections

• Connection busbars and cables are for electric distribution but also part of heat generation and distribution

• Nickel plate + spot welding = healthy low resistance connections

• Soldering, mechanical bolted connections, …


14s11p – 51.8V18.7Ah

• https://www.youtube.com/watch?v=8Xv8B93EoH0 Patreon

• Reusing batteries <1A (2-4 peak)

• Series path of paralleled pairs

• Soldered connections

• 2x2.5mm2 bus bars, 0.14mm2 fuse wire connections


4s30p – 16.6V80Ah

• https://www.youtube.com/watch?v=NGp7cGBYOLc&t=203s

• Reusage, sorting, …

• 15x8 Cell holders & domains of parallel cells

• Net of spot welded Ni-stripes (0.15 mm thick)


13s6p – 48V20Ah

• https://www.youtube.com/watch?v=Xoc4LIy5SnI Ebikeschool

• New batteries, sorted

• Hexagon fitted and glued cells

• Series connected stack of paralleled cells

• spot welded and soldered NI-stripes


BPD:EM

18650 Li-ion

• Standard (size) cylindrical Li-ion cells ø18h65mm

• ?– Nortvolt Lingonberry

21.70

– NV INR21/70 E1 vs P1


Sorting methods

• Sorting methods– Capacity and AC internal

resistance (C+ACIR)

– Electrochemical impedance spectroscopy (EIS)

– Voltage curve

– Cell dynamic parameters

– Cell thermal behaviour

• Dynamic parameters are in interest but improved SOC aging need to be studied before producing B-pack

Xiaoyu Li et. Al “A comparative study of sorting methods for Lithium-ion batteries”, ITEC Asia-Pacific, 2015


Nickel connection strips, BMS


Overview: BatPackDes

Battery Pack Design

Mechanical and electrical layout

Batteries thermal modeling

Battery management

Purpose, function, model Geometry, cell, module, pack

Cell design and thermal loads Cooling integration

Control and management (SOC) Usage and degradation (SOH)

BPD:intro


Goals

• Design and dimensioning of battery pack based on suitable models

– evaluate suitable battery technologies, specify celland packing, electric and thermal termination

– battery development and energy managementsystems, predict state of charge, health, function, ..

– test battery compatibility to operating conditions, current waveforms Ageing model

Thermal model

Electrical model

BPD:intro


Background A

• Vehicular application– Electrification improves energy

usage – hybrids

• use ICE at 35% instead of 10-20% efficiency

• Reuse deceleration energy for acceleration

– Pure renewable fuel/energy

• System view– Charging, static vs dynamic

– Compatability, AC current loading

Battery and Propulsion

BPD:intro


Background C

Machine PE Battery cell

Peak power density (kW/L) 1.5‐6.6 3.7‐17.2 0.5‐9

Peak specific power (kW/kg) 0.5‐2.5 4‐16.7 0.2‐4

M. Yilmaz P.T.Krein 2013

BPD:intro


PART-1: BPD.EMElectrical and mechanical layout

Function and realization

Performance chart

Cell construction and design

Pack specification

Characteristics and properties Models and tests

Cylindrical, prismatic, pouch design and realizations

Termination Modularity

BPD:EM



Comparison of vehicle battery types

B. Sarlioglu et al, “Driving toward accessibility” IEEE 2017BPD:EM


Comparison of battery cell types

B. Sarlioglu et al, “Driving toward accessibility” IEEE 2017BPD:EM


Overview of cell producers for xEVs

• It is easier to find producer than product ;)

BPD:EM


Vehicular application


Energy storage for vehicular application

• Battery – most important, currently most expensive

• Battery technology – in its infancy, expectedly continues to mature, reducing price and size, increasing capacity

• 2010 the cost of an EV battery per kilowatt-hour (kWh) ranged from US$600 to US$1,105 (2010). Last five years has brought the estimated price near US$500/kWh.

• Vehicular requirement (apart from no cost): Range=energy capacity, Acceleration=Power

BPD:EMhttps://www.youtube.com/watch?v=2PjyJhe7Q1g


Roadmap: from cell to pack

• Design– path from topology

sketching to practical realization

• Cell, Module, Pack/Bank• Battery = Energy storage

[Wh] & Power supply [W]– Applications: Vehicle/Grid– Technologies: Li-ion

• Battery cell– Geometries and

dimensions– Characteristics and

properties

• Cell “virtual” packing

• Electro-Thermal models

• Packing examples

• Thermal design– Cells, modules, backs

• Battery Management System

BPD:EM

Ageing model

Electrical model

current Thermal model

power

temperature voltage

DoD SoH


Battery back design & sizing

• Number of series connected cells in strings

– Ns=Udc/Ucell

• Number of parallel connected strings

– Np=Energy/(Ns*[Wh/kg]*[kg])

– Np=Energy/(Ucell*”cell capacity”)

• Circuits– Electric, thermal, etc

– Protection, surge, over voltageand overheat

BPD:EM

• Self study from page 161 – example cell selection consequences

– 300 V * 100 A

– Pmax = 2*30kW

– P/E ratio 2 and 20


Cylindrical, Prismatic, Pouch

• Hundred or thousands of series and parallel coupled cells to achieve the required power and energy

• Joining requirements: electrode-to-tab + case container

AnodeSeparator

Cathode

www.jmbatterysystems.comBPD:EM


Energy Management vs Design

• A cross-road of different disciplines

• Multi-dimensional (analysis) & multi-objective (synthesis)

Construction Production

Energy Conversion

kg kW, kWh

Pack specification

Pack architecture

Pack design

Electrical power system

Module design

Electrical distribution system

System safety

BMS design

Module CU

CELL

BPD:EM

•Joining methods

and E, M, T criteria?

Information

Energy• Monitoring – measure what

is important

• Control – keep it optimal and constrained

• Diagnosis – keep battery cells healthy


Specific energy and power• Specific energy

originates from material chemistry

– Capacity capability

• Specific power is related to material physics and production

– Internal power losses and thermal constrains –durability and safety

BPD:EMRagone plot


Value chain for EV batteries

• From cell realization to recycling (excluding raw materials)

• Vehicle power (performance), energy (range) and integration (BMS)

Fig.Ref.: B. Averill, P. Eldredge, “General Chemistry: Principles, Patterns and Applications”BPD:EM


BPD:EM

Lithium Battery Technologies

• Optimal performance and lifetime capacity

• Case sensitive: application vs cell configuration

Abbr Wh/kg

Lithium cobalt oxide LiCoO2 LCO

Lithium manganese oxide LiMn204 LMO 4.0V 114-159

Lithium iron phosphate LiFePO4 LFP 3.2V 114-138

Lithium nickel manganese cobalt oxide LiNiMnCo02 NMC 3.7V 93-171Lithium nickel manganese aluminum oxide LiNiCoAlO2 NCA

Lithium titanate Li4Ti5O12 LTO

R. Purkayastha, R.M. McMeeking, "A Linearized Model for Lithium Ion Batteries and Maps for their Performance and •What is and can be done?

Lund University / LTH / IEA / AR / MVKF25 / 2019-04-16 28 2828

Cell material properties example

materialThickness

[μm]

Thermal conductivity

[W/mK]

Electrical conductivity

[S/m]

+ I collector aluminum 20 238 37.8e6

+ Electrode 106 1.58 (wet) 13.9 (wet)

Electrolyte wet

Separator 25 0.34 (wet)

- Electrode 111 1.04 (wet) 100 (wet)

- I collector copper 14 398 59.6e6

case 162 0.16

M. Yazdanpour, “A circuit-based approach for electro-thermal modeling of Lithium-Ion batteries”

•What dimensions what materials?

BPD:EM

• Explore the ”rolled” structure inside the battery cells in order to study loss generation and dissipation


29

Cell construction

• Electrode arrangement: spiral wound jelly roll, stackedelectrodes, bobbin type

• Geometry: Cylindrical, Prismatic, Pouch, Button

www.toray-eng.com

• Components– Case: plastic (PET)

or metallic (steel, Al)

– Core=activecomponents+collectors, separator

– Terminals


Prismatic Cells

• Some cell producers– Hitachi, Samsung-SDI,

Panasonic (Sanyo)

– Northvolt Cloudberry173.115, Lingonberry NV INP27/91/148 L1 vs E1

• PHEV2 format

Prismatic cell

L, [mm] W, [mm] T, [mm] M, [kg] U, [V] C,[Ah]p,

[W/kg]c,

[Wh/kg]Hitatchi-1 148 91 26.5 0.72 3.6 28 2300 140

SDI-1 37SDI-2 60SDI-3 94

BPD:EM


Kokam’s SLPB cell

• SLPB – Superior Lithium Polymer Battery

• Pouch type improvedheat dissipation due to larger surfaces

• Example 240Ah 4.8kg cell

– Pheat=1.1kW @ 480A

– Acool=2x0.15 m2

– V=46.2x32.7x1.58 cm

Kokam.com

0 500 1000 1500 2000 250060

80

100

120

140

160

180

200

220

240

260

SLPB160460330

specific power, pcell

[W/kg]

spec

ific

ener

gy,

wce

ll [W

h/kg

]

Kokam large cells

BPD:EM


Specification list

LinkSource Sink

• Forced heating/cooling for battery back– Concepts, topologies, realization ideas, …

• Battery cell – Construction, properties, heat sources, thermal

loads, …

• Heat conductor– Thermal accessibility, thermal contacts, …

• Cooling plate– Realisation, performance, …

BPD:EM

BPD:TH


Thermal design

• Methods, models, calculation examples for thermal design

• Practical realisation examples from some car manufacturers

Heat

Electricity

BPD:TH

CELL

PACK

SYSTEM

• Chemistry

• Geometry

• Properties

• Thermal interface

• Coolingintegration


Thermal modelling

LinkSource Sink

• Models 1D, 2D, 3D analytic or numeric– Computation time vs accuracy, …

• Single cell, a module of cells, battery back – Specification of equivalent cell volume with specific losses, …

• Assembling, heat transport and temperature distribution– Mechanical assembly and thermal accessibility, thermal contacts

• Integration of active cooling circuits– Realisation, estimation of coolant flow and performance, …



Thermal integration• Power semiconductor

example

• Direct cooling where it is most needed in order to minimize heat transport through the solids that causes interior temperature rise and uneven temperature distribution

• Consider the effects of thermal cycling and expansion

• Experiences from other electric drive components


Cooling integration

• Cooling mechanisms

• Cooling flow determination

• Cooling duct and system design

• From rough design point of view – identify cooling surface and applied HTC on the surface


Cell library• Connect geometry and power

capability into battery-pack layout

• Selected cell examples: cylindrical, prismatic, pouch

• This information is used for virtual packing and rough estimation on temperature rise and distribution

Manufacturer

configuration Geometry Voltage CapacitySpecific power

Weight

[mm] [V] [Ah] [W/kg] [g]Panasonic Cylindrical Ø18.5x65.3 3.6 3.2 120 48.5

Hitatchi Prismatic 148x91x26.5 3.6 28 2300 720Kokam Pouch 462x327x15.8 3.6 240 360 4780


Cell “virtual” packing• For 300V there is need of 84 series

connected 3.6V cells

• First draft of 148x26.5 mm prismatic cell arrangement where 5 mm distance is left between the rows and groups of 7 cells

• First draft of ø18 mm 4 parallel cylindrical cell arrangement with cooling channel in between the cells

• Not only visualization but a parameterized model with coupling to finite element analysis (FEA)


Battery pack with cylindrical cells• “Empty” space between cells

• Cross-flow through battery module– Narrow spacing – expectedly no

cooling

– Large spacing for sake of better cooling is often considered impractical

• CFD vs “fast” design approaches


Battery back with prismatic cells

• Temperature homogenization analysis

• Analysis of thermal runaway


Battery pack with pouch cells• Coupled electro-thermal

FE+model order reduction (MOR) simulation compared to thermographic images

– A reduced order model (ROM) based on singular value decomposition (SVD)

• Direct air-cooled Li-ion pouch battery cell in order to improve the understanding (modelling) and practical realization of battery module


Chevy 104kW 20kWh• GM Volt and Spark EV use thin

prismatic shaped cooling plates in between the cells with the liquid coolant circulating thru the plate.

• The Volt cooling scheme is very effective from a cooling point of view but it is complicated. The cells are encased in multiple plastic frames


Tesla S 285kW 70kWh• Tesla snakes a flattened

cooling tube thru their cylindrical cells resulting in a very simple coolingscheme with very few points for leakage.


BWM i3 125kW 21-33kWh

• The BMW i3 cools the bottom of the battery case with refrigerant eliminating the liquid coolant entirely.

• New energy dense lithium ion cells (50% more)


Integration example by BMW


Integration example by Tesla

• 60kWh, 352V, 14 modules, 6216 cells in groups of 74=6x14

• 85kWh, 402V, 16 modules, 7104 cells


Integration example by Tesla


Accommodation of cylindrical cells


• Single stage heat transfer insufficient hA vs UA

Cool-plate and coolant


Heat transfer mapping

• Driving parameters for cooling P=f(out,Q) at in

• Flow (Re) and coolant (Pr) characterization

• Heat transfer – correlations (Nu) and – coefficient h

• Wall and winding temperature• Pressure across cooling

channel– Power for supply

• Expected cooling power P=f(w,Q) at in

0 100 200 300 400 500 600 700 800 900 100020

40

60

80

100

120

140

160

180

200

220

100100

100100 100

300

300

300300

500

500

500

500

700

700

700

700

900

900

900

1100

1100

1100

1300

1300

1300

1500

1500

flow rate, Q [L/min]

outle

t te

mpe

ratu

re,

out [C

]

Cooling power, p=cpQ(

out-

in) [W]

0 100 200 300 400 500 600 700 800 900 100020

40

60

80

100

120

140

160

180

200

220

200

200

200

400

400

400

600

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600

800

800

800

1000

1000

1000

1200

1200

1200

1400

1400

1600


outle

t te

mpe

ratu

re,

out [C

]

Reynolds number, Re=2dhQ/(A) [-]

0 100 200 300 400 500 600 700 800 900 100020

40

60

80

100

120

140

160

180

200

220

6.6

6.6

6.6

6.8

6.8

6.8

7

7

77.

2

7.2

7.2

7.4

7.4

7.4

7.6

7.6

7.6

7.8

7.8

7.8

8

8

8

8.2

8.2

8.4

8.6


outle

t te

mpe

ratu

re,

out [C

]

Nusselts number, Nu=f(Re,Pr) [-]

0 100 200 300 400 500 600 700 800 900 100020

40

60

80

100

120

140

160

180

200

220

340

360

360

360

380

380

380

380

400

400

400

400

420

420

420

440


outle

t te

mpe

ratu

re,

out [C

]

Heat transfer coefficient, h=Nu k/Dh [W/(m2K)]

0 100 200 300 400 500 600 700 800 900 100020

40

60

80

100

120

140

160

180

200

220

20

20

2020

40

40

40

40

60

60

60

80

80

80

100

100

120

120

140

160


outle

t te

mpe

ratu

re,

out [C

]

Temperature across boundary, Pcool

/(hAcool

) [C]

0 100 200 300 400 500 600 700 800 900 100020

40

60

80

100

120

140

160

180

200

220

20002000

40004000

60006000

8000

8000

80001000

0

10000

12000

12000

14000


outle

t te

mpe

ratu

re,

out [C

]

Pressure drop, dP [Pa]

0 100 200 300 400 500 600 700 800 900 100020

40

60

80

100

120

140

160

180

200

220

5050

50

100100

100

150150

150

200

200


outle

t te

mpe

ratu

re,

out [C

]

Ideal cooling supply power, dPQ [-]

0 100 200 300 400 500 600 700 800 900 10000

50

100

150

200

250

100

100100 100

300

300

300300

500

500

500

700

700

700

900

900

900

1100

1100

1300

1300

1500


wal

l tem

pera

ture

,

out [C

]

Cooling power, p=cpQ(

out-

in) [W]

0 5 10 15 20 25 30 35 40 45 5020

21

22

23

24

25

26

27

28

29

30


outle

t te

mpe

ratu

re,

out [C

]

cooling power, p=cpQ(out

-in) [W]

10001000

1000

10001000

4000

4000

4000

4000

7000

7000

7000

10000

10000

10000

13000

13000

c=3500J/kgK, =900kg/m3

B. Sundén, “Introduction to Heat transfer”


Thermal analysis of cell assembly

• Geometric data– Defined by German standard

DIN 91252

• Heat transfer inside the cell

– From cell to module and pack

– Cell = Jelly-roll (heater) + carrier (assembly)

• Heating power – Worst case P=I2Ro=50W

Hitachi 3.6v 35Ah 0.8mΩ@10A155x27x118 incl terminals 810g


Thermal accessibility of a cell

• Available thermal connection areas

– Large long sides2x134cm2 but low thermal conductivity

– Sides, lateral sides2x24cm2 and Bottom side39cm2

• Bottom and short sides have expectedly betterinherit thermal contact


Inside a battery cell

• Cell dimensions are known, jelly-roll geometry only guessed

• Heat conductivity defined in-plane and cross-plane for whole cell unit and jelly roll (including heat capacity)

• Important part for thermal models are termination and equivalent jelly-roll

DIN SPEC 91252:2011Lundgren et al 2016

H. Lundgren et al, ”Thermal Management of Large-Format Prismatic Lithium-Ion Battery in PHEV Application”


Surface temperature response

• Thermal vs electric power extraction and comparison

• Thermal conductivity– Through-foil

0.95W/mK– Along foil 30.8 W/mK

H. Lundgren et al, ”Thermal Management of Large-Format Prismatic Lithium-Ion Battery in PHEV Application”


2D FE over cross-sections

CaseQbase

[W]Qlateral

[W]max

[oC]

1 50 0 60

2 33 17 55

3 21 29 44λcell=1 W/mK

λcell=20 W/mK

Qv=140W/dm3, surf=30oC

6054484236

Temperature , [C]

30

2

1

3


Observations A

• Battery cell– P=50 W heating, 1/R=0.6 0.5 0.28 K/W, Δ=30 25 14 K

• Heat conductor– Ideal 1/R=0 K/W, Δ=0 K

• Cooling plate– Ideal fluid=wall=surf=30oC

LinkSource Sink

50 W per cell

surf=30oC wall=30oC fluid=30oCcell= surf+Δ


Realization A

• Mechanical assembly in “cross” plane direction

• Thermal enhancement both in plane directions

– Lateral clamp or forcing plate

– Battery to base contact

• ..


Cell clamped into heat conductor

CaseQbase

[W]Qlateral

[W]max

[oC]

1 34 16 51

2 32 18 54

3 27 23 72

Qv=140W/dm3, surf=30oC

6054484236

Temperature , [C]

30

-0.08 -0.06 -0.04 -0.02 0 0.02 0.04 0.06 0.08

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

length, [m]

heig

ht,

[m]

10μm gap Δgap=3oC100μm gap Δgap=21oC

3

2

1


Cell linked to cool-plate

CaseQbase

[W]Qlateral

[W]max

[oC]

1-30 36 14 53

2-h1 35 15 68

3-h2 35 15 148

Qv=140W/dm3, fluid=25oC

6054484236

Temperature , [C]

30

h1=1000W/Km2 wall Δwall=15oCh2=200W/Km2 wall Δwall=95oC

-0.1 -0.08 -0.06 -0.04 -0.02 0 0.02 0.04 0.06 0.08 0.1

-0.02

0

0.02

0.04

0.06

0.08

length, [m]

heig

ht,

[m]

32

1


Transient heating

• 5 minutes between the frames (FEMM transient HT)

• Hot side of the scale (usually presented in between 20-30oC)

• One dominating heat capacitance only


Summary

• Battery cell– Δb=30 25 14 K @ 50W – actual load is lower

• Heat conductor– Insufficient thermal contact 0.1 mm air Δc=20K @ 50W

• Cooling plate– Insufficient heat transfer h2=200W/Km2 wall Δwl=95oC

LinkSource Sink

50 W per cell

surf= wall+Δc wall= fluid+Δw fluid=30oCcell= surf+Δb


Thermal design, control and management

• .J. Li, Z. Zhu, “Battery Thermal Management Systems of Electric Vehicles”, MSc Chalmers 2014

• 29.5/17.7 kWh &1700/270 kg

l11: batteries mechanical and electrical layouts · l11: batteries mechanical and electrical...

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