Current Trends in Battery
Technology
ECV national seminar 24.9.2014
Samu Kukkonen
VTT Technical Research Centre of Finland
Structure of the Presentation
 1. Introduction, what was said in the previous ECV-seminar
 2. Conventional technologies: Lead-Acid, NiMH, and Li-Ion
 3. The future in brief
 4. Exercise: specifying a battery for eBus
 5. Summary
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2
Introduction - What was said in ECV-seminar on
9/2013




Storing electrical energy is difficult in technology and business wise
Li-Ion remains the high capacity technology of the 2010s
Next generation batteries not appearing until after 2020
Cost of batteries is still high but falling
 300 €/kWh in 2020 on a system level for PHEV/EV?
 The cost and performance of present batteries has reached a critical level for
cost effective (hybrid) electric commercial vehicles but implementation requires
careful engineering and solutions
 Applied battery R&D is the focus of ECV-eStorage3. Supporting the industry
with experimental, modelling, and literature work.
 This is still true in 9/2014 but what about the cost estimate?
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3
The conventional
technologies
Lead-acid, NiMH, and Li-Ion
4
Trends in SLI Lead-Acid Batteries
 The increasing electrification in conventional passenger vehicles puts extraordinary
demands for SLI batteries





Electric power steering
Electric AC
Start/stop, power boost, recuperation capabilities, etc.
Upcoming electric turbo chargers
(Automated driving)
 According to the Volkswagen group, the dynamic upper limit for 12 V SLI battery current
is 200 A
 2009- Audi A8 the current demand is 180 A
 2011- Audi A6 the current demand is 290 A! Two batteries required!
 Advancements in lead-acid technology have been made in e.g. power
capability and deeper cycling ability. However, this might not be enough
  New interest for 48 V systems has arisen especially in premium German brands
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Trends in Automotive NiMH Batteries
 Nickel-metal hydride batteries have proven their safety, performance,
and lifetime in mild- and full hybrid applications
 Advantages (when compared to Li-Ion) include simpler BMS, thermal
management and better safety and calendar lifetime
 Disadvantages: Significantly lower energy content and cyclic lifetime
© Toyota
 Nickel as a material is expensive, large NiMH battery systems are
expensive and will probably remain so
 NiMH is the intermediate battery technology
 Mild-hybrids
 Full-hybrids
 Next gen. 48 V systems?
 However, there are few interesting developments happening in NiMH
technology, for example the Swedish Nilar stacked NiMH batteries
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© Nilar
6
Trends in Automotive Li-Ion Technology – First
the Basics
 Lithium-ion technology consists of several anode/cathode
material options and additives which determine the
characteristics of a Li-Ion battery
 In 2014, the primary material families are still
 Anode: graphite and LTO
 Cathode: NMC, NCA, LMO, and LCO
© Chevrolet
 In addition to materials, a cell construction can be
optimized to emphasize certain characteristic like energy
density
 Several new materials are under heavy research to
increase energy content and lower the costs.
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Trends in Automotive Li-Ion Technology – Li-Ion
Chemistry Characteristics
GraphiteNCA
GraphiteNMC
GraphiteLMO/Blend
GraphiteLFP
LTO-NMC
Safety
+
++
++
+++
++++
Energy
++++
+++
+++
++
+
Lifetime
+
+++
++
+++
++++
Charging
+++
+++
+++
++
++++
Cost
++++
+++
+++
++++
+
Supply
+++
+++
++
++++
++
Tesla
Model S
Seems to
be the best
compromise
German
EVs.
Varying
lifetimes
depending
on blend.
Japanese
and USA
EVs.
Chinese are
flooding the
market.
Disparities
in quality. A
real choice
for ECVs.
Expensive
but very
durable,
and high
power. A
real choice
for ECVs.
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Trends in Automotive Li-Ion Technology – Li-Ion
Suppliers and Applications
GraphiteNCA
GraphiteNMC
GraphiteLMO/Blend
Suppliers
Panasonic…
Samsung, LiTec…
AESC, LG
Chem, Li
Energy
Japan…
A123, ATL,
Calb, BYD,
Lishen
Tianjin,
Saft…
Toshiba,
Altairnano,
Tiankang…
Applications
Tesla Model
S
VW eUp,
eGolf, BMW
i3, Daimler
Smart, Fiat
500
Nissan Leaf,
Chevrolet
Volt, Renault
Zoe
Chevrolet
Spark EV,
Coda EV,
eBuses
Mitsubishi iMiEV, Honda
Fit, eBuses
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GraphiteLFP
LTO-NMC
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Trends in Automotive Li-Ion Technology – Li-Ion
Suppliers in China
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Trends in Automotive Li-Ion Technology – The
Challenges
 Electric passenger cars have fundamental challenges
 Range
 Cost
 Lifetime and safety of the batteries
 However, Tesla Model S has proven that 500 km EV is possible
with current technology
 Also, Tesla could bring battery prices significantly down
 Lets take a closer look…
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Trends in Automotive Li-Ion Technology – Case
Tesla Model S and Nissan Leaf
 Tesla Model S
 Nissan Leaf
 Range 500 km (NEDC)
 85 kWh Panasonic graphiteNCA battery
 Cell format is standard 18650
 7104 cells total!
 Range 200 km (NEDC)
 24 kWh AESC graphiteLMO/Blend battery
 Cell format is custom pouch
 192 cells total
 Quite a feat to manage
MTBF!
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Trends in Automotive Li-Ion Technology – Case
Tesla Model S and Nissan Leaf
 Tesla Model S – Implications of
using 18650 cells
 Nissan Leaf – Implications of
using custom pouch cells
 18650 is mature technology
 Small cells, easier safety concept
 Large battery, less lifetime
requirement
 630 Wh/l, 233 Wh/kg cell level
 Cost estimate of cells: 184 $/kWh
(2015) Source: AABC
 Manufacturing process is still
evolving for pouches
 Large cells need to be safe
 Small battery, high lifetime
requirement
 309 Wh/l, 155 Wh/kg cell level
 Cost estimate of cells: 213
$/kWH (2015) Source: AABC
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Trends in Automotive Li-Ion Technology – Tesla
Gigafactory
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Near-future technologies
(2015 – 2020) and beyond
briefly
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Near Future Technologies and Beyond - What is
taking so long ?
 Specific energy (Wh/kg) =
𝐶𝑎𝑝𝑎𝑐𝑖𝑡𝑦 𝐴ℎ ∗𝑉𝑜𝑙𝑡𝑎𝑔𝑒 (𝑉)
𝐴𝑐𝑡𝑖𝑣𝑒 𝑀𝑎𝑠𝑠𝑒𝑠 𝑜𝑓 𝐴𝑛𝑜𝑑𝑒 𝑎𝑛𝑑 𝐶𝑎𝑡ℎ𝑜𝑑𝑒 (𝑘𝑔)
 Some fundamental challenges:
 Increasing voltage beyond 4,5 Volts causes present day
electrolytes to decompose
 Increasing capacity and reducing mass requires new
anode/cathode materials
 Finding new electrolytes has proven difficult
 Developing new stable materials that have the capacity but also
safety, lifetime, power, efficiency, low cost, etc. is also difficult
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Near Future Technologies and Beyond – What is
under research and when are they available?
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Near Future Technologies and Beyond – REDOX
Flow Batteries
 In REDOX flow batteries the reactants
are stored in tanks in liquid state
 The battery can be recharged or the
contents in the tanks can be emptied
and refilled (much like filling your car)
 The size of the tanks determines the
energy
 The size of the battery stack determines
the power
 Lifetime is very long
 Already in commercial operation as
stationary grid energy storage
 Could this be scaled down to ECVs?
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© New energy and fuel
Enervault 1 MWh, 250 kW REDOX
battery in California
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Exercise: Choosing and
dimensioning a Li-Ion
battery/chemistry for
eBus
eBus Battery Exercise – Requirement
Specification
 Objective: Dimension a battery for opportunity charged eBus operating
in HSL bus line 11 (in Espoo) and discuss about the cost and lifetime
 Assumptions
 Charger in Tapiola, Espoo is 250 kW, 8 minutes of charging after each
roundtrip
 One roundtrip is 20 km in distance
 The eBus consumes 1 kWh/km during summer and 1,5 kWh/km during
winter
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eBus Battery Exercise – Dimensioning
 Worst case round-trip energy consumption: 1,5 kWh/km * 20 km = 30 kWh
 Available charging energy = 250 kW * 1 h * 8 min / 60 min = 33,3 kWh
  Usable energy needs to be 30,0 kWh (with safety margin!) with 250 kW
charging acceptance
 Li-Ion LTO batteries are safe, accept the charging power, and have the lifetime
 Li-Ion LFP batteries are cheaper, safe enough, can accept the charging power
when over-dimensioned, but is lifetime enough?
 The options in this exercise:
Altairnano LTO: 2,26 Volts, 60 Ah, 360 A charging acceptance, 16 000 cycle
lifetime (on paper)
A123 LFP: 3,3 Volts, 19,5 Ah, 58,5 A charging acceptance, 3000 cycle
lifetime (on paper)
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eBus Battery Exercise – Dimensioning
 The requirements: 30 kWh each roundtrip, 250 kW charging
 Dimensioning:
 Altairnano 60 Ah LTO: 272s2p = 615 Volts, 73,8 kWh, 440 kW, and 1525 kg
 This leaves 43,8 kWh headroom for energy and 190 kW for charging. Total
eBus range: 49 – 74 km.
 A123 19,5 Ah LFP: 186s9p = 614 Volts, 108 kWh, 325 kW, and 1661 kg
 This leaves 78 kWh headroom for energy and 75 kW for charging. Total eBus
range: 72 - 108 km.
 The cost of the batteries is estimated to be equal
 Lifetime of the batteries determines the total-cost-of-ownership between
the two options
 However, A123 gives added value with significantly larger 78 kWh headroom
and thus range.
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eBus Battery Exercise – Battery Lifetime
 Battery lifetime behaves non-linearly as a function of temperature, power, used
SoC range and time.
 Could I calculate the following?
 Altairnano 16 000 full cycles: 16 000 * 49 – 74 km = 784 000 km – 1 184 000 km
 A123 3000 full cycles: 3000 * 72 – 108 km = 216 000 km – 324 000 km
 The calculation is not correct because lifetime is non-linear
 A123 has much more room for degradation than Altairnano. If safety can be
confirmed, the battery can be used beyond common end-of-life condition of 80
% original capacity.
 Which one has the better TCO?
 Difficult to answer, assessing lifetime requires laboratory testing, field testing ,or
07/11/2014 modelling approaches
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Summary
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Summary
 There is limited improvement potential in Lead-Acid and NiMH
 The present day Li-Ion is the technology of the 2010s
 It is difficult to estimate when new technologies are commercially
available
 Many ECVs are feasible with the current technology. But careful
research and engineering is required.
 VTT is here for the industry. We aim to research and serve as
the necessary knowledge center for batteries and ECV systems.
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TECHNOLOGY FOR BUSINESS