The Generation Professionals Group is for utility professionals who work in biomass, coal, gas/oil, hydro, natural gas, or nuclear power generation fields. 

WARNING: SIGN-IN

You need to be a member of Energy Central to access some features and content. Please or register to continue.

Post

Battery Breakthroughs

image credit: © Denys Zazimko | Dreamstime.com

This item is part of the Energy Storage - Special Issue - 07/2020, click here for more

1. Introduction

Elon Musk keeps suggesting that “Battery Day” will be really big. Originally he indicated it would be in April, delayed it to May. Then he said it will be sometime in June. As I’m starting to write this on June 20, he said that it will be combined with the upcoming shareholder meeting, which was scheduled for July7, but he is delaying that also. He now says that this combined event will be on September 22.

So I’m diving into this subject without him. I am describing the Lithium Ion chemistries he is currently using in Section 2. In Sections 3 and 4 I will discuss new findings regarding advanced technologies and materials that Elon may use. In section 5 we will look at a reasonable projection of future battery pricing. In the last section, I will briefly repeat some information from the last section of my last Elon post, and relate it to earlier information in this post.

In the earlier post, we talked about the “million mile battery”, and although this will be big news, it will not be the biggest news. I believe that an announcement of a future major reduction in battery pricing driven by improved energy density and simplified production will make the biggest headline. This will facilitate many other advancements in battery electric vehicles (BEVs), battery energy storage systems (BESS), and other technologies that depend on these (like EV supply equipment (EVSE), intermittent renewable mitigation, vehicle-to-grid (V2G) and other grid-storage applications).

To prepare for the above, Tesla appears to be prepping to build a battery research and manufacturing facility. Although Elon threatened to leave California, this facility will be in Fremont, CA where Tesla’s mothership BEV manufacturing plant is.[1]

2. Lithium Ion Chemistries

The following are the chemistries that Tesla currently uses:

Lithium Nickel Manganese Cobalt Oxide (LiNiXMnYCoZO2), NMC: This chemistry can be optimized for power or energy-capacity by adjusting the specific cathode chemistry (X, Y and Z above). This especially applies to vehicular applications vs. battery energy storage systems (BESS). It is used for many battery electric vehicles (BEVs), but Tesla uses it for its BESS applications (Powerwall and Powerpack). The market share of the NMC chemistry is increasing as it displaces older designs.

Lithium Nickel Cobalt Aluminum Oxide (LiNiXCoYAlZO2), NCA: This chemistry is the current capacity-champion. It has characteristics similar to NMC, and costs less, but has a reduced safety tolerance. Tesla uses this chemistry for its vehicles. The reduced safety tolerance means that the battery management system must make sure that the batteries stay in a safe operating domain (over-the-air upgrades are good). I believe Tesla/Panasonic also incorporates safety devices in each cell.

LFP (LiFePO4 or 4Lithium Iron Phosphate) Tesla may be planning to use CATL’s design for a million mile battery based on this chemistry, even though it has a lower energy density than the above two. CATL is Contemporary Amperex Technology, Ltd. The Chinese company signed a two-year deal to supply batteries for Tesla's Model 3 cars in February. Its other clients include BMW, Daimler, Honda, Toyota, Volkswagen and Volvo.

At least one source[2] has suggested that CATL may be evolving this chemistry from a graphite anode to a lithium metal anode. Batteries with a lithium metal anode are frequently referred to as lithium metal batteries. Making this upgrade to an LFP battery would roughly double the energy density of this design.

Note that a lithium metal anode also can be to upgrade other chemistries, including NMC (but not the NCA).

3. A Million and Much More

As I was reading articles on various improvements Tesla is planning for batteries, one of these gave me a link to a paper from Jeff Dahn’s team that really focuses on battery longevity. As a reminder, this team from Dalhousie University (Nova Scotia, Canada), developed an advanced design for NMC Lithium Ion batteries. Jeff (and one assumes his team) now leads Tesla’s Advanced Battery Research program in Canada.

The subject paper is referenced here.[3] Note that this was published in September of last year. I will summarize this below, and would recommend that readers consider reading it themselves. However first, two definitions:

Discharging a battery at 1C means that the battery is discharged so that it is completely depleted in 1 hour. Thus if a battery has a capacity of 100 amp-hours at 1C, it can be discharged with an output of 100 amps for 1 hour. Note that the capacity increases with slower discharge and decreases with faster discharge. Longer discharge periods are usually formatted C/N. For instance a 2-hours discharge would be C/2.

We defined the three chemistries that Tesla is looking at in section 2. The referenced paper mostly looks at NMC. To specifically define an NMC battery you need to chemically specify the quantities of its cathode components, and the material used in its anode, like: LiNi0.5Mn0.3Co0.2O2/artificial graphite. This battery has a metallic-oxide cathode composed of lithium plus nickel, manganese and cobalt oxides (in the proportions indicated) and an artificial graphite anode. A short-hand format for this would be NMC532/AG.

Some of the details I took away from this paper is that there are many methods to extend battery longevity. These include: specific battery design elements, how batteries are charged, stored and discharged, and battery operating temperature. Secondary elements can be used to control all of the above use-related and environment-related elements. For instance, improved cooling and battery-packaging can reduce the operating temperature and thus extend the lifetime (see chart below).

In the above chart, note that the blue lines are for BEVs (top numbers, note that 1 million miles is roughly 1.6 million km) and the black lines are for BESS. DOD is depth of discharge, 20°C is 68°F and 40°C is 104°C. Also note that Tesla’s BEV designs use the heat pump or air conditioner to cool their battery packs.

Use cycles for BESS are much easier to control than for BEVs. However as battery packs become larger in the latter application, many of the elements of the use-cycle (like operating temperature) become easier to control. Larger battery packs could be driven by the desire for more mileage, higher performance and/or applications with larger vehicles (read: Tesla Simi).

4. Dry Battery Electrode (DBE)

Tesla recently bought Maxwell whose primary products are energy storage devices, albeit ones with substantial differences from lithium ion batteries. Maxwell makes ultracapacitors. These devices can charge and discharge much more rapidly than batteries, but have a lower energy density.

However, it is believed that Elon’s primary interest in them is NOT ultracapacitors, but instead a major component of these devices that can be also be used in batteries: the dry battery electrode. The primary source for this section is a paper written by the primary developers of this technology, and referenced here.[4]

…Unlike conventional slurry cast wet coated electrode, Maxwell’s DBE offers significantly high loading and produces a thick electrode that allows for high energy density cells without compromising physical properties and electrochemical performance. Maxwell’s DBE exhibits better discharge rate capability than those of wet coated electrode. Maxwell has demonstrated scalability by producing robust self-supporting dry coated electrode film in roll form with excellent long-term electrochemical cycle performance, and established large pouch cell prototypes in greater than 10Ah format…

Maxwell Technologies is a San Diego-based ultracapacitor manufacturer that uses a proprietary solvent-free electrode production process. Advanced process development without the need for solvents has enabled Maxwell’s dry coating electrode production lines to operate at high throughput using a minimal manufacturing footprint. This unique electrode manufacturing process does not introduce any volatile waste products into the atmosphere or require complex manufacturing plant arrangements. It begins with dry raw materials and maintains its liquid-free state throughout the subsequent processing steps to ultimately produce a robust high-performance ultracapacitor electrode.

For the past several years, Maxwell has been engaged in research and development efforts to expand the application space of its dry coating electrode process technology to apply to battery electrode manufacturing processes. Cell performance using prototype dry coated lithium-ion battery electrodes has been demonstrated. Dry coated electrode configuration with various architectures using a wide range of materials can be produced at thicknesses ranging from about 50 microns to about 1 millimeter. In addition to manufacturing flexibility, the cohesion and adhesion properties of electrodes derived from the dry coating process are superior in the presence of electrolyte at high temperatures compared with those produced using the wet coating technology.

This unique electrode process technology offers significant saving in manufacturing cost and helps curb CO2 pollution in the battery electrode manufacturing process. By eliminating the use of any solvents, and the associated coating and drying complexity inherent in wet coating technology, the dry coating electrode process is environmentally friendly, and can be readily installed and commissioned with a much lower start-up capital investment. Thus, dry coating electrode manufacturing is economically attractive and socially responsible.

Maxwell’s proprietary dry coating electrode technology is comprised of three steps: (i) dry powder mixing, (ii) powder to film formation and (iii) film to current collector lamination; all executed in a solventless fashion. Maxwell’s dry coating electrode process is scalable, and can accommodate current lithium ion battery chemistry and advanced battery electrode materials. In this report, the robustness of the dry coating electrode process is demonstrated using a host of commercially available anode materials such as silicon based materials and lithium titanate (LTO), as well as cathode materials such as layered Li(NixMnyCoz)O2 (NMC), LiNi0.8Co0.15Al0.05O2 (NCA), LiFePO4 (LFP) and sulfur. All dry powder materials were mixed using Maxwell’s proprietary dry coating process to yield a final powder mixture consisting of active material, binder and conductive additive as shown in figure below (left). This powder mixture was calendered to form a continuous self-supporting dry coated electrode film that is wound in roll form (right). A wide range of dry coated electrode configurations can be produced by the adjustment of film processing conditions to control material loading weights and active layer thickness.

Image Credit: John Benson

Various dry coated battery electrodes were fabricated, including NMC811, NCA, LFP, LTO, sulfur/carbon and silicon composite, using Maxwell’s dry coating electrode technology. Maxwell’s dry coating electrode technology can be used to produce advanced high capacity NMC811 cathode and silicon-graphite composite anode that can deliver designed discharge capacity… The NMC811 dry coated electrode exhibited typical discharge profile with stable voltage plateau at the end of the discharge process. The Si/Graphite composite dry coated electrode produced electrochemical characteristic of delithiation (The removal of lithium from an electrode of a lithium-ion battery) of silicon at around 0.5V that significantly enhances energy density…

In addition to higher power performance demonstrated in high energy density cells using dry coating, electrodes derived from a solvent-free process can also be robustly cycled at 100% depth of discharge using a charge/discharge rate of 0.5C/1C, respectively.

5. The Magic Number

There is a “magic number” in the electric vehicle (EV) industry: $100 per kWh. Why is this a magic number? Read on.

The battery pack is the most expensive component in a mass-produced EV. When the cost of this battery reaches roughly $100 per kWh of capacity, BEVs will reach initial purchase price parity with internal combustion powered vehicles (ICVs). BEVs already have many inherent advantages over ICVs. I wrote one of my first posts on BEVs over two years ago, and this is linked below. In section 4 of this paper, I pointed out the intrinsic and political advantages BEVs have over ICVs.

https://energycentral.com/c/pip/evolution-battery-electric-vehicles-and-their-supply-equipment

An analysis in reference 2 above shows that Tesla is approaching the magic number, and will likely pass this within a few years. In addition to the components reviewed in this post, I believe this is also because of their much greater experience in mass producing battery packs for BEV and operating experience by those BEVs, than any other BEV manufacturer.

Increasing cap and trade and carbon tax adders to the price of gasoline and diesel will make the operating cost of ICVs much more expensive than BEVs (it’s already significantly higher – read the above linked post).

6. Previous Design Elements

In early 2019 Jeff Dahn and his team at the Dalhousie University (Nova Scotia, Canada), developed an advanced design for NMC Lithium Ion batteries. Tesla has filed for a new patent on which Jeff Dahn and his team are listed as inventors… They claim it reduces costs, enhances performance and lifetime of Li-ion batteries.

I’m guessing that the above design is compatible with dry battery electrodes (section 3), which would explain why Elon bought Maxwell.

Another innovation from Mr. Dahn’s team is a battery systems with fewer operative, electrolyte additives. This design seems to be compatible with both BEVs and large BESS. This improvement also enhances performance and lifetime of Li-ion batteries, while reducing costs verses other systems that rely on more additives.

I wouldn’t be surprised if Maxwell had tested Mr. Dahn’s additives.

Less than a year ago Tesla acquired a battery manufacturing and engineering company: Hibar Systems. This company specialized in building manufacturing equipment for different processes in battery manufacturing. Hibar’s offerings include an advanced Automated Vacuum Filling Systems for Lithium-ion batteries. Recently, it offered a full 'high-speed Lithium-ion battery manufacturing system.

Note that most of the above components and processes (including dry battery electrodes) simplify and accelerate the manufacturing of lithium ion batteries. Also most (if not all) of the above are heavily protected (read: patents or proprietary designs). It is clear Mr. Musk wants to go to a place where no one else can follow (including ICVs). It should be fun watching Tesla dominate the BEV and BESS markets.


[1] M. Corey Goldman, The Street, “Tesla-Digs-Deeper-Into-California-With-New-Battery-Facility”, June 25, 2020, https://www.thestreet.com/video/tesla-digs-deeper-into-california-with-new-battery-facility

[2] Juan Carlos Zuleta, Seeking Alpha, “Why Tesla Should Be Aware Of The New 'Holy Grail' In Lithium Batteries”, June 10, 2020, https://seekingalpha.com/article/4352962-why-tesla-should-be-aware-of-new-holy-grail-in-lithium-batteries

[3] Jessie E. Harlow, Xiaowei Ma1, Jing Li, Eric Logan, et al, Dalhousie University, “A Wide Range of Testing Results on an Excellent Lithium-Ion Cell Chemistry to be used as Benchmarks for New Battery Technologies”, Sep 6, 2019, https://iopscience.iop.org/article/10.1149/2.0981913jes

[4] Hieu Duong, Joon Shin & Yudi Yudi, Maxwell Technologies, Inc., “Dry Electrode Coating Technology”, http://www.powersourcesconference.com/Power%20Sources%202018%20Digest/docs/3-1.pdf

John Benson's picture

Thank John for the Post!

Energy Central contributors share their experience and insights for the benefit of other Members (like you). Please show them your appreciation by leaving a comment, 'liking' this post, or following this Member.

Discussions

Bob Meinetz's picture
Bob Meinetz on Jul 26, 2020 3:10 am GMT

John, do you have any numbers on round-trip efficiency for these batteries including bidirectional inversion?

John Benson's picture
John Benson on Jul 27, 2020 5:38 pm GMT

Hi Bob:

In one of my earliest posts on Energy Central (first link below), I drilled down into the gory details of all storage chemistries. Per this (section 3.1) and the sources referenced therein, the round-trip efficiency was 89% to 90%. Since this was writem almost 3 years ago, I did a queck with a more recent trusted source (second link below) and it listed 85% for this metric. It should be noted that charging and discharging efficiency is highly dependant on the duty cycle, and battery energy storage systems can be designed for a specific set of cycles over their lifetime.

https://energycentral.com/c/iu/energy-storage-survey

https://atb.nrel.gov/electricity/2019/index.html?t=st

I've not heard of bidirectional inversion. I did a brief search on the web, and couldn't find any trusted sources that covered this.

-John

Bob Meinetz's picture
Bob Meinetz on Aug 3, 2020 2:47 pm GMT

John, bidirectional inversion is simply converting from AC to DC for storage and back again.

The best bi-directional inverters for low-voltage applications are 90-92% efficient, and a 2018 study found that V2G (Vehicle to Grid) charging / discharging was 53-62% efficient - useless for any practical application.

Comments on “Measurement of power loss during electric vehicle charging and discharging” – Notable findings for V2G economics

Proponents' argument that high-voltage inversion is far more efficient ignores the fact high voltage must ultimately be converted to 3.8 volts to be stored in any lithium-ion battery - no matter the capacity, no matter the current.

 

Jim Stack's picture
Jim Stack on Jul 31, 2020 3:43 pm GMT

John great article. Tesla Power Packs are the best and actually are getting lower in cost and longer lasting. Progress on batteries has been similar to the Intel Moores law. Now it's Elon's law of batteries. He predicted a 7% increase each year and has beat that so far. Solid state batteries are very close and that will be another giant leap for stored power. 

John Benson's picture
John Benson on Jul 31, 2020 6:50 pm GMT

Still lots of R&D to do on solid-state electrolyte. I keep seeing incremental improvements on this path like the one linked below. Toyota is projecting 2025, and they are one of the leaders in this development.

https://www.designnews.com/electronics-test/solving-vexing-solid-state-lithium-ion-battery-problem

Elon's new batteries will (still) be announced on Sep 22, and I expect we will start seeing them in BEVs or BESS within six months (albeit in small quantities). He is starting to ramp up his manufacturing of his own battery designs -- see the link below.

https://electrek.co/2020/07/29/tesla-expanding-battery-cell-manufacturing-team-hiring-production-associates/

Larry Eisenberg's picture
Larry Eisenberg on Aug 6, 2020 3:08 pm GMT

Excellent overview of available battery technologies.

In my opinion, the needed transformatiom of the world's electricty supply system will require a vast expansion in grid scale battery / energy storage technology. 

There have been recent developments in energy storage technologies other than those mentioned here that hold a great deal of pomise to produce low cost, environmentally friendly, grid scale solutions.  On that list, I would include organic chemistry batteries, isentropic heat storage, solid material hear storage, and tower based pumped hydro.  Some of these are entering the marketplace, and some are just around the corner. The price point for these technologies is much better than the currently available options.

If we are going to successfully eliminate the use of fossil fuels in energy production, the advancement of these technologies is critical and worthy of public and private investment to get over the hump and make them widely available.

John Benson's picture
John Benson on Aug 6, 2020 8:04 pm GMT

Hi Larry, thanks for the comment.

I write frequently on storage, including all of the above.

Rather than listing all of my papers on storage, I will send you to a more comprehensive resource. The link below is to a list of all of my papers that I publish quarterly. After you download this pdf, start by reading the Introduction (Section 1)- all papers are indexed by section, briefly described and have links to the paper in Energy Central. The Intro describes how to use this capability.

Most of the papers on storage are is section 5 - Renewables & Microgrids, but since I cover Tesla in detail, some information is in section 4 - Mobility.

More specific to your comment, one of my earliest papers (2017) - Energy Storage Survey covers most of the subjects in your response it is near the end of section 5 in my list. I checked the link to this paper and it still works, but you might get an error message (paper still comes up).

https://energycentral.com/c/pip/list-papers-posted-energy-central-subject-second-quarter-2020

One other thing - My post next Tuesday will deal heavily with storage (and Tesla). It's called VIrtual Resources.

-John

Get Published - Build a Following

The Energy Central Power Industry Network is based on one core idea - power industry professionals helping each other and advancing the industry by sharing and learning from each other.

If you have an experience or insight to share or have learned something from a conference or seminar, your peers and colleagues on Energy Central want to hear about it. It's also easy to share a link to an article you've liked or an industry resource that you think would be helpful.

                 Learn more about posting on Energy Central »