electrochemical pathways towards...

Donald R. SadowayDepartment of Materials Science & Engineering

Massachusetts Institute of TechnologyCambridge, MA 02139-4307

U.S.A.

Electrochemical Pathways

Towards Sustainability

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outline of this morning’s talk

the energy storage landscape

innovation in energy storage electrometallurgical approach for stationary storage applications

innovation in metals extraction electrochemical approach to zero-emissions smelting

misconceptions about batteries

๏ not much has changed: not true!

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electrochemistry and energy storage: noble origins

electrical energy storage (Wh/kg) (MJ/kg)

lead acid 35 0.13

NiCd 45 0.16

NaS 80 0.28

NiMH 90 0.32

Li ion 150 0.54

gasoline 12000 43

misconceptions about batteries

๏ not much has changed: not true!

๏ no Moore’s Law (transistor count doubles every 2 years)

๏ all microelectronics are silicon-based

๏ all new batteries are based on entirely new chemistries radical innovation

different approaches for different applications

๏don’t pay for attributes you don’t need

๏ cell phone needs to be idiot-proof

๏ car needs to be crashworthy

๏ how about service temperature? human contact?

๏ stationary batteries: more freedom in choice of chemistry but very low price point

market price points

application price point

communications $1,000 / kWh

automobile traction $250 / kWh

laptop computer $2,000 - $3,000 / kWh

severity of service conditions price

stationary storage $100 / kWh

storage is the key enabler๏ for deployment of renewables:

intermittency obstructs contribution to baseload

๏ for load leveling, load following, frequency regulation, off-peak capture: colossal battery

๏ for grid-level storage, battery vs combustion need to think differently

๏ today’s Li-ion batteries fail badly the whole is less than the sum of its parts: plinergy

๏ confine chemistry to earth-abundant elements to make it dirt-cheap, make it out of dirt

๏ look at the economy of scale of modern electrometallurgy:

aluminium smelter

how to think about inventing a colossal yet cheap battery

bauxite, carbon, 13 kWh electricity, $5000/tonne capital cost

metal cost < 50¢/lb

a modern aluminium smelter

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15 m × 3 m × 1 km × 0.8 A⋅cm−2

Charles Martin Hall, USAPaul L.T. Héroult, France

1886

how to think about inventing a colossal yet cheap battery: pose the right question

…into thisconvert this…

aluminium potline

350,000 A, 4 V

start with a giant current sink

15 produce liquid metals at both electrodes

why is an aluminium cell not a battery?

frozenbath

960°C960°C960°C960°C

liquid metal battery

work started 5 years ago with internal funding from the Deshpande Center and the Chesonis Family Foundation

refractory lining

refracto

on discharge

liquid metal

battery

refracto

Mg(liquid) ! Mg2+ + 2 e-

on discharge

liquid metal

battery

refracto

Mg(liquid) ! Mg2+ + 2 e-

Mg2+ + 2 e- ! Mg(liquid alloy)

on discharge

liquid metal

battery

our sponsors

$4 million

$7 million

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laboratory-scale test cell

1 Ah“shotglass”

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electropositive anode

molten salt electrolyte

electronegative cathode

cell section after cycling 48 h at 700°C

1 Ah“shotglass”

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“hockey puck” “personal pizza”

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Cell Current density Cycles Cycles

analyzedColumbic efficiency

Energy efficiency Fade rate Capacity

density Utilization Electrode cost

Reason for decommission

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mA / cm2 % % % / cycle Ah/cm2 % $ / kWh

250 100 10 99 67 0 0.6 77 90 Test complete

cycle testing of cell 11 (20 Ah)

attributes of all-liquid battery

all-liquid construction eliminates any reliance on solid-state diffusion

long service life

all-liquid configuration is self-assembling expected to be scalable at low cost

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liquid-liquid interfaces are kinetically the fastest in all of electrochemistry

capable of handling high currents

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Liquid Metal Battery

???

LMB status report

liquid metal battery works: almost 400 cells tested many chemistries: alloys and salts

capacity fade as low as 0.05% / cycle

accelerating scale-up to self-heating cell startup company Liquid Metal Battery Corp.

©2011 LIQUID METAL BATTERY CORPORATION!proprietary & confidential

20110913 EPRI-LMBC slidedeck September 13, 2011 16

towards commercialization

!  founded 2010

!  series A: Bill Gates & TOTAL   patient investors   significant ability to support subsequent capital intensive investment

!  focus on commercialization & scale-up

LIQUID METAL BATTERY CORPORATION

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problems with metals extraction

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steelmaking makes CO2 2 FeO + C = 2 Fe + CO2

(½ kg C / kg Fe) x 1.8 billion tonnes

sundry HAPs including Mn & Pb, polycyclic organics, benzene, & CS2

unfavorable by-products L

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why is metal production so dirty?

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many processes are over 100 years old

r attitude then of indifference towards the environment

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where do metals come from?

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occur naturally as compounds

beneficiated high-purity feed

reducing agents: H, C, M, e-

options for sustainability?

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where do metals come from?

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occur naturally as compounds

beneficiated high-purity feed

reducing agents: H, C, M, e-

options for sustainability?

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beyond the blast furnace

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most metals are found in nature as oxides

“like dissolves like”

e- is the best reducing agent

extreme form of molten salt electrolysis

molten oxide electrolysis:

where pure oxygen gas is the by-product

MMMMM

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๏ electrolytic route from ore to liquid metal viable at industrial scale: aluminium worldwide capacity exceeds 45 million tpy

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replace C with e-: reductant and fuel

๏ decompose Al2O3 dissolved in Na3AlF6 (T = 960°C) liquid Al (-) and CO2 (+) find an inert anode & molten oxide electrolyte

Charles Martin Hall, USAPaul L.T. Héroult, France

1886

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๏ temperature above 1538°C

๏ current flow generates heat by Joule effect

๏ carbon-free iron product in the liquid state

๏ oxygen by-product: environmentally beneficial commercial value

๏continuous process: periodic feeding of iron oxide periodic removal of liquid iron

(FeOx ) = Fe(l) + x2 O2 (g)

liquid iron

iron

NOT TO SCALE

molten oxide electrolysis (MOE)

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attributes of MOE (1)

๏ extraction is carbon-free no emission of CO2, SO2, NOx

๏ cell operates at 1600°C production of molten steel in a single reactor

๏ iron oxide fed directly into the cell fewer unit operations lower cost

๏ tonnage oxygen also produced marketable by-product

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cokeoven

sintering

blastfurnace

basic oxygen furnace

refining, casting, rolling, shaping

molten oxide electrolysis

refining, casting, rolling, shaping

\

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T = 1600°C

cathode collector:making liquid iron

anode lead:making oxygen

-

+

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electrolysis of Fe2O3 at 1570°C as seen through port in cell cap

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constant-current electrolysis at 1575°C

current density: ~1 A cm-2

iron

electrolyte

Mo crucible

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more electrolytic production of molten iron:

iron

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producing oxygen on an inert anode

anode after 2.5 h electrolysis at 1.5 A.cm-2, T = 1565°C

5 mm

metallic alloy core

frozen slag

oxide layer

point defect model (D.D. MacDonald)

๏MOE industrial cell will be self-heated by the Joule effect

๏ energy efficiency and metal purity can be assessed only in an internally heated cell

Joule effect!(+)!

Reaction heat!(-)!

Natural convection!(-)!

Radiation!(-)!

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next step: internally heated cell

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notional design of self-heating cell

anodeø 40 cm

cathodeø 50 cm

slagø 4 cm

NOT TO SCALE

2

other attributes of MOE ironmaking

๏ uses existing† supply chain for iron oxide feed

๏ produces metal of superior quality in liquid state (no carbon, sulfur, nitrogen, or hydrogen)

๏ lower threshold tonnage at lower capital cost

๏ zero carbon emissions from smelter

๏ potential to produce high-quality steels, e.g., stainless

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metal ball at bottom of cathode metal ball on floor of cell

production of nickel by MOE

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production of ferrochromium by MOE

Fe-Ni-Cr alloy

towards electrolytic stainless steel

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production of liquid titanium by MOE

frozen electrolyte

titanium puddle

Mo crucible

cathode: Mo

anode: C

current density ∼1 A/cm2

T = 1725°C

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production of rare-earth metals by MOE?

stay tuned!

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electrochemistry and energy storage: noble origins bright future

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electrochemistry and energy storage: noble origins bright future

Ernest Rutherford

electrochemical pathways towards...

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