A lithium ion battery is based around the transfer of lithium ions (Li+) from an anode to a cathode whe being charged and reverse when being consumed.
The idea here is to create a bacterially-based cathode (and possibly even anode) by making the bacteria secrete the ions and then nucleate them in an encapsulation reaction
Cathode FePO4 - accepts Li ions and stores them in cathode, diffuses into the anode. Charge by moving from A to C. When not plugged in ions diffuse to A. Idea here is to change the cathode. Because we can encapsulate bacteria in solutions, coat each bacterium with this FEPO4 layer and place in matrix. Acts as a cathode in the system. Cheaper as you can grow your cathode
Take a flask, induce them to coat in FePO4 and concentrate/dry them into a tube. Put tube in Li ion solution.
- less toxic
- increased Li+ transport can enhance energy storage
- production processes can be much more benign than the harsh chemistry normally needed
- 1) Making cobalt oxide coating for anode
dip a polymer electrolyte (conducts electricity) into a solution of engineered viruses. The viruses assemble into a uniform coating on the electrolyte. This coated electrolyte is then dipped into a solution containing battery materials
- 2) Making iron phosphate coating for cathode
Because proteins that encapsulate the viruses recognise and bind specifically to certain materials such as carbon nanotubes in this case, each iron phosphate nanowire can be electrically ‘wired’ to conducting carbon nanotube networks (conducts electricity). Electrons can travel along the carbon nanotube networks, percolating throughout the electrodes to the iron phosphate and transferring energy in a very short time.
Electrically address electrode materials with poor electronic conductivity through nanoscale wiring of active materials
|Cathode Material||Average Voltage||Gravimetric Capacity|
|LiCoO2||3.7 V||140 mAh/g|
|LiMn2O4||4.0 V||100 mAh/g|
|LiFePO4||3.3 V||150 mAh/g|
|Li2FePO4F||3.6 V||115 mAh/g|
|Anode Material||Average Voltage||Gravimetric Capacity|
|Graphite (LiC6)||0.1-0.2 V||372 mAh/g|
|Li4Ti5O12||1-2 V||160 mAh/g|
|Si (Li4.4Si)||0.5-1 V||4212 mAh/g|
|Ge (Li4.4Ge)||0.7-1.2 V||1624 mAh/g|
Q&A Development phases
Phase 1 - Compounds/threshold/detection
- Which chemical do we produce?
- How do we produce the required chemicals for the encapsulation?
- How much do we produce?
- Is there a toxic level?
Phase 2 - Encapsulation
- How long does encapsulation take?
- What are concentrations required?
- Which nucleation sequence on the membrane-bound protein is better?
- How do we measure for successful nucleation?
Phase 3 - Killing strategy/gene deletion
- Is it a really needed step in this project?
- How do we measure for successful deletion?
Phase 4 - Storage
- How do we create block cathodes that don't degrade: Biofilm?
- How much Li+ do we put?
Phase 5 - Delivery
- What technique are we going to use to make the bacteria into cathodes?
Issues to solve
How to conduct electricity for our model
- 1) any conducting wire?
- 2) clumping together of encapsulated cells? (eg biofilm?)
- 3) Can the bacteria produce the FePO4 as at the moment it is essentially like a bead of FePO4.
- 4) FePO4 is needed for the nanoparticle technology, but since we are using bacteria, can use different compounds? MnO?
- 5) The battery limited by Li ions so it is a self regenerating (not self charging) battery.
Key facts from reference:
A virus injects its genome into bacterium (host cell) and this produces more viruses. Can engineer bits on virus that stick to carbon nanotubes providing a matrix. On other side coated with FePO4 acts as your cathode.
Li ions attach. When charged up, the system becomes a cathode. Smaller and cheaper. Anode is just graphite and all this is your battery. Li ions all over the place.
So instead of working with viruses (so infectious they will go everywhere, so infectious) and single walled nanotubes (expensive), use a matrix where bacteria coated in FePO4 swimming around in a contained ‘biofilm’.
What we have is a cheap cathode and a growing one, essentially growing your own batteries.
Biomanufacturing route. Would be a laptop battery.