Next Generation Energy Storage for Integration with Sensors and Power Generation

Rich Winslow Jay Keist Joe Wang Dr. Christine Orme Dr. Chun Hsing Wu Bernard Kim Prof. Paul Wright Prof. James Evans Prof. Malcom Keif Prof. Xiaoying Rong

UC Berkeley UC Berkeley UC Berkeley LLNL ITRI UC Berkeley UC Berkeley UC Berkeley Cal Poly Cal Poly

•  Energy  storage  essen,al  for  a)  Everyday  devices  

b)  Extensive  deployment  of  renewables  

•  Ba:eries  and  supercapacitors  have  a  major  role  in  suppor,ng  such  applica,ons  

•  Zinc  is  cheap,  non-­‐toxic,  abundant;  yielding  a  poten,al  high  energy  density  ba:ery  

•  Hitherto  zinc  ba:eries  have  not  been  rechargeable  

•  Prior  work  at  UC  Berkeley  shows  that  zinc  rechargeable  ba5eries  possible  using  ionic  liquid  electrolytes.    

Background  on  Zinc  Ba5eries  

Zinc  

•  Background  on  manufacturing  ba:eries  and  supercapacitors  by  prin,ng  

•  Recent  basic  work  on  zinc  deposi,on  •  Integra,on  with  thermoelectric  genera,on  and  supercapacitors  

•  Need  for  large  scale  energy  storage  •  First  successes  in  flexographic  prin,ng  

Outline  

•  Electrochemical  reac,ons  require  surfaces  (heterogeneous  reac,ons)  

•  Manufacturing  ba:eries  (or  supercapacitors)  requires  the  crea,on  of  large  surface  area  per  cm3  

•  Prin,ng  creates  large  surface  area  per  cm3  (even  more  if  “ink”  produces  porous  electrodes)  

The  Prin@ng  Concept  

100 µm

Importance  of  Morphology  in  Zinc  Ba5ery  Cycling  

•  Deposi,on  from  aqueous  electrolyte  –  repeated  cycling  impossible  

•  Gel  polymer  ionic  liquid  electrolyte  permits  recycling  –  why?  

•  Answer  from  surface  characteriza,on  techniques:  •  Op,cal  microscopy  •  Electrochemical  AFM  •  USAXS  

What  is  a  Capacitor?  

Energy  storage  device  for  high-­‐power,  low-­‐energy  applica,ons  

tradi,onal  capacitor   electric  double-­‐layer  capacitor  (supercapacitor)  

parallel  plates  

dielectric  

electric  field  

C.  Ho,  R.  Winslow,  P.  Wright,  J.  Evans  

Ho  et  al.  (2010)    

Current  electrochemical  capacitor    performance  

Capacitance   Max.  Power   Energy  Density  Opera,ng  Voltage  

100  mF/cm2  600  μW/cm2  60  mW/cm3  50  W/kg  

10  μW-­‐hr/cm2    1  mW-­‐hr/cm3    1  W-­‐hr/kg  

0-­‐2  V  

Current  microba5ery  performance  

Capacity   Energy  Density  Opera,ng  Voltage  

1  mAh/cm2  

1.5  mWh/cm2    150  mWh/cm3    130  Wh/kg  

1-­‐2  V  

Printed Microbatteries and Supercapacitors

Nickel  Current  Collector  

Ac,vated  Carbon  Electrode  

Gel  Electrolyte  

Component  Inks  

Printed  Supercapacitor  Performance  Ac,vated  carbon  (cast)  

Current  collector  

Electrode  

Electrolyte  

Integrated Device Concept

Thermoelectric  Voltage  (V)  

Thermoelectric  Power  (mW)  

1.6   0.35  

Target prototype specifications

Current draw from Texas Instruments MSP430 radio

Sleep  mode  draw:  0.6  mA  

Ba5ery  Capacity  (mAh)  

Capacitor  Power  (mW)  

0.80   51  

Cur

rent

(mA

)

Time (ms)

Hot  Side  

Cold  Side  

Sensors  

Printed  Carbon/

Ionic  Liquid  Capacitor  

Printed  Zn/MnO2  Ba5ery  

Printed  Thermoelectric  Generator  

Sb2Te3  Sb   Te  

1.  Ball  Mill   3.  Mix  Thoroughly  

4.  Print  Thermoelectric  Inks  

N-­‐type  Bi2Te3+Epoxy  Polymer  P-­‐type  Sb2Te3+Epoxy  

2.  Add  Powders  to  Epoxy  

Epoxy  

Chen  et  al.  (2011)  

Printable Thermoelectric Slurries

Printable Power Source: Thermoelectric (L); Microbatteries (M); Supercapacitors (R)

Integrated printed thermoelectric prototype featured on the cover of the Journal of Micromechanics and Microengineering

Printed Energy Generation and Storage

Figure  from  Laurent  Pilon,  Transport  Phenomena  in  Electrochemical  Energy  Storage  Systems  (seas.ucla.edu/~pilon/EDLCs.htm)  

Comparison  of  Power  Sources  

Flexographic Printing

Drying Substrate/Webbing

Cathode Printing Electrolyte Printing

Drying Drying

Anode Printing

Mul,-­‐sta,on  commercial  flexographic  printer  at  Cal  Poly,  SLO   Flexographically  Printed  Cathode  

Yield Stress Determines Ink Structural Properties

15  µm  

Three  Layer  Flexographic  Print  MnO2  Cathode  

0.5  cm  

Printed and Cast Battery Components

Cycle  Life:  Over  100  cycles  Printed  Cell:  50-­‐100  mAh/cm3      Rechargeable  AA:  120-­‐250  mAh/cm3  

Electrochemical Characterizations

Zn  Foil  

Printed  MnO2  

Dispenser  Printed  Gel  Electrolyte  

SS  Foil  

One  Cycle  

Conclusions  

•  We  have  a  be:er  understanding  of  why  zinc  ba:eries  can  be  made  rechargeable  

•  We  are  revisi,ng  printed  supercapacitors  

•  We  have  printed  TEGs  and  integrated  them  with  a  printed  ba:ery  

•  We  have  collaborated  with  Cal  Poly-­‐SLO  on  flexographic  prin,ng  of  cathodes  as  first  step  in  prin,ng  grid  scale  ba:eries.