Cell production and charging (out of MA)

[Artful Dodger]

50MW of solar needed just to charge them...
Good thing the roof will hold a 70 MW system

Lithium NCA battery cells aren't in a low state of charge upon assembly. The chemical constituents aren't purchased in a chemically reduced state for use during cell manufacture. So the cells don't need to be charged before they go on to the next step of pack assembly.

It's a common assumption that secondary (rechargable) batteries need to be charged after they're made, but that's not how it works. Just ask yourself why primary (non-rechargable) batteries don't need to be charged when you buy them. Uh huh that's right, you CAN'T recharge a primary cell. Why would 2ndry cells be manufactured any differently?

Cheers!

 

[AWDtsla]

Lithium NCA battery cells aren't in a low state of charge upon assembly. The chemical constituents aren't purchased in a chemically reduced state for use during cell manufacture. So the cells don't need to be charged before they go on to the next step of pack assembly.

It's a common assumption that secondary (rechargable) batteries need to be charged after they're made, but that's not how it works. Just ask yourself why primary (non-rechargable) batteries don't need to be charged when you buy them. Uh huh that's right, you CAN'T recharge a primary cell. Why would 2ndry cells be manufactured any differently?

Cheers!

The cells have to go through a charge cycle in the factory to form a good SEI layer.

 

[mongo]

Lithium NCA battery cells aren't in a low state of charge upon assembly. The chemical constituents aren't purchased in a chemically reduced state for use during cell manufacture. So the cells don't need to be charged before they go on to the next step of pack assembly.

It's a common assumption that secondary (rechargable) batteries need to be charged after they're made, but that's not how it works. Just ask yourself why primary (non-rechargable) batteries don't need to be charged when you buy them. Uh huh that's right, you CAN'T recharge a primary cell. Why would 2ndry cells be manufactured any differently?

Cheers!

Of course single use cells are a one way chemical reaction, but are you sure about no initial charge for Li Ion? The chemistry and process is totally different than say a lead acid (pre charged plates), zinc air, or zinc carbon type.
Regarding Li-ion manufacturing:

... The electrolyte has to wet the separator, soak in, and wet the electrodes. The wetting and soaking process is the slowest step and therefore is the determining factor in the speed of the line. All other needed insulators, seals, and safety devices are then attached and connected. Then, the cells are charged the first time and tested. Often cells have to be vented during the first charge. First charging cycles follow sophisticated protocols to enhance the performance, cycling behavior, and service life of the cells. Recently, efforts have been made in combined and hybrid processing, such as direct deposition of separators onto electrodes and rapid heat treatments.

From
Materials and Processing for lithium-ion Batteries
And also:
Lithium Battery Manufacturing

Cylindrical Cell Manufacturing Equipment Solutions | Targray

 

[Artful Dodger]

are you sure about no initial charge for Li Ion?

Yes, pretty sure. This short video from PNW Nat'l Lab shows the manufacturing process. Do you want to know more about the chemistry? That's where the electrical potential energy is stored in the ingredients before assembly into cell. Cheers!

 

[mongo]

Yes, pretty sure. This short video from PNW Nat'l Lab shows the manufacturing process. Do you want to know more about the chemistry? That's where the electrical potential energy is stored in the ingredients before assembly into cell. Cheers!

Nice video on the physical construction.
However, I think it skipped the other remaining steps for brevity.
This equipment manufacturer calls out an initial charge.
Lithium-ion Pouch Cell Manufacturing Equipment Solutions | Targray

Step 3:

Use Battery Analyzer to charge & discharge the cell. This enables battery formation and sends excess gas to gas receiver.

Cut off gas receiver and use Vacuum Sealing Machine to finalize sealing on cutting edge under vacuum/glove box.

Here is the entire Li-po pouch cell process
How Lithium Polymer Batteries are Made - learn.sparkfun.com

Once sealed, we can now call this thing a battery. This is the first charging cycle. You can see the plastic clips that clamp down on the exposed tabs. The small wing left on the battery is there to collect any electrolyte or gas that is pushed out during this first cycle.

Article on the SEI formation process:
Charged EVs | New protocol reduces Li-ion battery formation time by a factor of six

Doubt this is an issue, but if you Google "lithium battery initial charge", the links are related to the consumer side of things after manufacturing has prepped the cell.

 

[Artful Dodger]

Nice video on the physical construction.
However, I think it skipped the other remaining steps for brevity.

Hi Mongo. So I think I see why we're talking past each other. There is a distinction between an "initial charge" (your term, not actually used in the Tangray.com link) and "cycling" a new battery cell.

Most manufacturers will run their newly made cells through from 2-4 discharge/charge cycles to break in the cell. The first discharge will be to made to ~25% DOD, then 50% on the 2nd cycle, 75%, and 100%, then finally back down to 70% DOD for storage and shipping.

But the 1st action during break in is a shallow discharge. The battery is at full state of charge as soon as its assembled. This is easy to verify with a voltmeter. The cell is assembled with active compounds, not discharged/spent compounds than need to be recharged. This is also easy to see in the appearance of the electrolytes between a fully charged cell and a discharged one. And yes, a SEI layer forms with most Li-Ion chemistries over the 1st few charge cycles, which also makes the cell look different from new.

Now for the important part, which gets back to your original statement that GF1 would need 150 GWh of PV to charge its annual production of battery cells. Newly built cells do not need an "initial charge", the chemical potential energy is already in the enclosed compounds. They DO need to be cycled a few times to break them in, but that is not a full loss process.

Typically, cell testing rigs discharge one bank of cells by applying a load to another bank of storage cells. Then when the test rig recharges the cell being tested, the energy is returned from the storage cells. Back and forth, back and forth a few times. Yes it's not free (coulomb effic. losses, wiring and electronics losses, cell heating) but it's no where near the energy required to fully charge a depleted cell.

So that's probably where we're talking past each other. "Initial charge" might be a shorthand way to refer to the charge cycling performed during the break-in process, but it is a sloppy shorthand that has lead to a lot of confusion about the chemistry involved.

Charge cycling/break-in is not like "filling the cell with electricy" for the first time with a new battery cell as many people assume. The "gas tank" isn't empty when its built, because it's not a gas tank.

See 1:24 of this video for an example of cycling the cells, which they call 'aging', and I call break in.

Note that if you buy RC LiPo cells from HobbyKing, those cells have never been cycled and have about a 10% failure rate. Most RC users perform 3-4 shallow cycles on their new batts to break them in. Most quality RC chargers actually have a mode to do this now, and allow you to attach an external battery to sink the energy during the cycling. Kinda like the big boys like Panasonic.

So Peace?

 

[mongo]

Hi Mongo. So I think I see why we're talking past each other. There is a distinction between an "initial charge" (your term, not actually used in the Tangray.com link) and "cycling" a new battery cell.

Most manufacturers will run their newly made cells through from 2-4 discharge/charge cycles to break in the cell. The first discharge will be to made to ~25% DOD, then 50% on the 2nd cycle, 75%, and 100%, then finally back down to 70% DOD for storage and shipping.

But the 1st action during break in is a shallow discharge. The battery is at full state of charge as soon as its assembled. This is easy to verify with a voltmeter. The cell is assembled with active compounds, not discharged/spent compounds than need to be recharged. This is also easy to see in the appearance of the electrolytes between a fully charged cell and a discharged one. And yes, a SEI layer forms with most Li-Ion chemistries over the 1st few charge cycles, which also makes the cell look different from new.

Now for the important part, which gets back to your original statement that GF1 would need 150 GWh of PV to charge its annual production of battery cells. Newly built cells do not need an "initial charge", the chemical potential energy is already in the enclosed compounds. They DO need to be cycled a few times to break them in, but that is not a full loss process.

Typically, cell testing rigs discharge one bank of cells by applying a load to another bank of storage cells. Then when the test rig recharges the cell being tested, the energy is returned from the storage cells. Back and forth, back and forth a few times. Yes it's not free (coulomb effic. losses, wiring and electronics losses, cell heating) but it's no where near the energy required to fully charge a depleted cell.

So that's probably where we're talking past each other. "Initial charge" might be a shorthand way to refer to the charge cycling performed during the break-in process, but it is a sloppy shorthand that has lead to a lot of confusion about the chemistry involved.

Charge cycling/break-in is not like "filling the cell with electricy" for the first time with a new battery cell as many people assume. The "gas tank" isn't empty when its built, because it's not a gas tank.

See 1:24 of this video for an example of cycling the cells, which they call 'aging', and I call break in.

Note that if you buy RC LiPo cells from HobbyKing, those cells have never been cycled and have about a 10% failure rate. Most RC users perform 3-4 shallow cycles on their new batts to break them in. Most quality RC chargers actually have a mode to do this now, and allow you to attach an external battery to sink the energy during the cycling. Kinda like the big boys like Panasonic.

So Peace?

Oh, peace for sure.
Agree Tesla/ Panasonic is using their power conversion technology to move charge between charge and discharge cycles.

Still hazy on the manufacturing first charge bit though.
Anode is the negative electrode made of graphite.
Cathode is the positive electrode made of NCA/NMC.
Discharge happens as lithium ions and electrons go from anode to cathode. So initially, there are no lithium ions at the anode (graphite), are there? Or is it doped ahead of time? Is the situation different for Lithium titanate anodes?

 

[JRP3]

I thought I saw a post stating that new cells don't need charging but can't seem to find it now. In case i wasn't imagining things new cells need a "formation" charge, as well as cycling to check capacity and internal resistance.
Example Importance of the constant voltage charging step during lithium-ion cell formation - ScienceDirect

Edit: I see a new thread was created to address this topic.

 

[JRP3]

Lithium NCA battery cells aren't in a low state of charge upon assembly. The chemical constituents aren't purchased in a chemically reduced state for use during cell manufacture. So the cells don't need to be charged before they go on to the next step of pack assembly.

To be clear cells are charged and discharged before being assembled into packs.

 

[Chickenlittle]

Extremely informative discussion. Do they use the energy discharged to charge other batteries that are being cycled?

 

[mongo]

To be clear cells are charged and discharged before being assembled into packs.

Yah, @Artful Dodger and I agree there. The question is the amount of energy needed to do that. Do they start with usable energy or not...

Now for the important part, which gets back to your original statement that GF1 would need 150 GWh of PV to charge its annual production of battery cells. Newly built cells do not need an "initial charge", the chemical potential energy is already in the enclosed compounds. They DO need to be cycled a few times to break them in, but that is not a full loss process.

Extremely informative discussion. Do they use the energy discharged to charge other batteries that are being cycled?

Given Tesla's bidirectional power conversion technology (and the general cell manufacturing state of technology) , I would be really disappointed if they dumped the cell's energy into heat instead of recycling it...

 

[Artful Dodger]

I would be really disappointed if they dumped the cell's energy into heat instead of recycling it...

Yes, a production scale cell testing rig would be set up to capture energy in a battery bank during test cell discharge, and feed it back to that cell during charge. I expect PV and powerpacks will also be integrated with this process to allow 24/7/364 operations on 100% renewables. Cheers!

 

[Artful Dodger]

This journal article provides an extensive description of the manufacturing process for lithium ion battery cells, and proposes an optimized test rig configuration for production:

Mueller, Verena, et al. "Introduction and application of formation methods based on serial-connected lithium-ion battery cells." Journal of Energy Storage 14 (2017): 56-61.

A B S T R A C T
The process step of formation is one key process to guarantee high performance, long-lasting and safe automotive lithium-ion cells. Since the formation of the cell is the most expensive process in cell manufacturing, reducing process cost and time is advanced. The state-of-the-art formation process includes the cycling of lithium-ion cells each on its own power electronic channel which amounts to about 38% of the total formation costs. Therefore, this paper proposes an optimized formation method by serial-connected lithium-ion cells. Due to small resistance and capacity deviations conditioned by manufacturing tolerances, charge balancing is necessary for formation of serial-connected cells. This paper introduces several serial interconnection circuits for serial cell formation, like passive balancing or drop out system. Furthermore, the associated influences on the formation process parameters, e.g. the charging profile and the charge current control are investigated. The comprehensive comparison of serial formation techniques reveals cost reduction potentials and challenges regarding the process control

Also in Muller (2018) [linked by JRP3 above], the author says "The cells were filled with 8 g electrolyte and sealed under vacuum. After a total soaking time of 3 h the cells were pre-charged with a current of 0.2 A for 3.5 h" which is a 35% SOC for a 2 Ahr cell.

I think this can fairly be called the initial charge referred to by Mongo. It also implies that 20 gWh of annual battery production will consume over 7 gWh of electrical energy during initial production of the cell, then more during testing (charge/recharge cycling)

Really enjoying this thread, and learning lots. Thanks!

Cheers!