CHANNELS

Aerospace

Automotive

Automated & Autonomous Vehicles

Battery & Electrification Technology

Defense

Drone TV

Electronics

Manufacturing & Prototyping

Materials

Medical

Motion Control

RF & Microwave Technology

Robotics & Automation

Sensors & IoT

Test & Measurement

Aerospace
Automotive
Automated & Autonomous Vehicles
Battery & Electrification Technology
Defense
Drone TV
Electronics
Manufacturing & Prototyping
Materials
Medical
Motion Control
RF & Microwave Technology
Robotics & Automation
Sensors & IoT
Test & Measurement
Aerospace & Defense
Search Results

A New, Cheaper Way to Make Li-ion Batteries

An MIT team has designed a system that uses flames to produce costly materials for cathodes of Li-ion batteries. The system promises to be simpler, much quicker, and far less energy-intensive than the conventional method now used to manufacture cathode materials. Watch this video to see what the electrochemical tests showed about how their materials performed compared to those currently used in electric vehicles.

“Our first thought was, what if we can mix together all of the substances — including the lithium — at the beginning?” says Assistant Professor, Sili Deng  . “Then we would not need to have the two stages” — a clear simplification over coprecipitation.

Topics:
Batteries Electrification Energy Power

More From SAE Media Group

    Transcript

    00:00:03 the MIT energy initiative presents using combustion to make Lithium-ion batteries electricity storage for the energy transition written by Nancy W Stouffer for more than a century much of the world has run on the combustion of fossil fuels now to avert the threat of climate change the energy system is changing notably solar and wind systems

    00:00:25 are replacing fossil fuel combustion for generating electricity and heat and batteries are replacing the internal combustion engine for powering Vehicles as the energy transition progresses researchers worldwide are tackling the many challenges that arise silly dang has spent her career thinking about combustion now an assistant professor in the department of mechanical engineering

    00:00:46 and the class of 1954 Career Development Professor Doug leads an MIT group that among other things develops theoretical models to help understand and control combustion systems to make them more efficient and to control the formation of emissions including particles of soot so we thought given our background in combustion what's the best way we can contribute to the energy transition says

    00:01:09 Deng in considering the possibilities she notes that combustion refers only to the process not to what's burning while we generally think of fossil fuels when we think of combustion the term combustion encompasses many high temperature chemical reactions that involve oxygen and typically emit light and large amounts of heat she says given that definition she saw another role for

    00:01:31 the expertise she and her team have developed they could explore the use of combustion to make materials for the energy transition under carefully controlled conditions combusting Flames can be used to produce not polluting soot but rather valuable materials including some that are critical in the manufacture of Lithium-ion batteries improving the lithium-ion battery by

    00:01:52 lowering costs the demand for Lithium-ion batteries is projected to Skyrocket in the coming decades batteries will be needed to power the growing Fleet of electric cars and to store the electricity produced by solar and wind systems so it can be delivered later when those sources aren't generating some experts project that the global demand for Lithium-ion

    00:02:12 batteries may increase 10 fold or more in the next decade given such projections many researchers are looking for ways to improve the lithium-ion battery technology Deng and her group aren't materials scientists so they don't focus on making new and better battery chemistries instead their goal is to find a way to lower the high cost of making all those batteries and much

    00:02:33 of the cost of making a Lithium-Ion battery can be traced to the manufacture of materials used to make one of its two electrodes the cathode the MIT researchers began their search for cost savings by considering the methods now used to produce cathode materials the raw materials are typically salts of several Metals including lithium which provides ions the electrically charged

    00:02:54 particles that move when the battery is charged and discharged the processing technology aims to produce tiny particles each one made up of a mixture of those ingredients with the atoms arranged in the specific crystalline structure that will deliver the best performance in the finished battery for the past several decades companies have manufactured those cathode materials

    00:03:14 using a two-stage process called co-precipitation in the first stage the metal salts excluding the lithium are dissolved in water and thoroughly mixed inside a chemical reactor chemicals are added to change the acidity the pH of the mixture and particles made up of the combined salts precipitate out of the solution the particles are then removed dried ground up and put through a sieve

    00:03:37 a change in PH will cause lithium to precipitate so it is added in the second stage solid lithium is ground together with the particles from the first stage until lithium atoms permeate the particles the resulting material is then heated or annealed to ensure complete mixing and to achieve the targeted crystalline structure finally the particles go through a diaglomerator

    00:03:58 that separates any particles that have joined together and the cathode material emerges co-precipitation produces the need of materials but the process is time consuming the first stage takes about 10 hours and the second stage requires about 13 hours of annealing at a relatively low temperature 750 degrees Celsius in addition to prevent cracking during

    00:04:21 annealing the temperature is gradually ramped up and down which takes another 11 hours the process is thus not only time consuming but also energy intensive and costly for the past two years dag and her group have been exploring better ways to make the cathode material combustion is very effective at oxidizing things and the materials for Lithium-ion batteries are generally

    00:04:43 mixtures of metal oxide so sting that being the case they thought this could be an opportunity to use a combustion-based process called Flame synthesis a new way of making a high performance cathode material the first task for Deng and her team mechanical engineering postdoc Jian and Zhang Valerie L mondoon sb20 sm22 and

    00:05:06 current graduate students manasa bat and shui Zhang was to choose a Target material for their study they decided to focus on a mixture of metal oxides consisting of nickel Cobalt and manganese plus lithium known as NCM 811 this material is widely used and has been shown to produce cathodes for batteries that deliver high performance in an electric vehicle that means a long

    00:05:30 driving range rapid discharge and recharge and a long lifetime to better Define their target the researchers examine the literature to determine the composition and crystalline structure of ncm-811 that has been shown to deliver the best performance as a cathode material they then considered three possible approaches to improving on the co-precipitation process for

    00:05:51 synthesizing NCM 811 they could simplify the system to cut Capital costs speed up the process or cut the energy required our first thought was what if we can mix together all the substances including the lithium at the beginning system then we would not need to have the two stages a clear simplification over co-precipitation introducing fasp

    00:06:14 when process widely used in a chemical and other Industries to fabricate nanoparticles is a type of flame synthesis called Flame assisted spray paralysis or fasp deng's concept for using fast to make their targeted cathode powders proceeds as follows the precursor materials the metal salts including the lithium are mixed with water and the resulting solution is

    00:06:36 sprayed as fine droplets by an atomizer into a combustion chamber there a flame of burning methane heats up the mixture the water evaporates leaving the precursor materials to decompose oxidize and solidify to form the powder product the Cyclone separates particles of different sizes and the bag house filters out those that aren't useful the collected particles would then be

    00:06:58 annealed and de-agglomerated to investigate and optimize this concept the researchers developed a lab scale fast setup consisting of a homemade ultrasonic nebulizer a preheating section a burner a filter and a vacuum pump that withdraws the powders that form using that system they could control the details of the heating process the preheating section

    00:07:19 replicates conditions as the material first enters the combustion chamber and the burner replicates conditions as it passes the flame that setup allowed the team to explore operating conditions that would give the best results their experiments showed marked benefits over co-precipitation the nebulizer breaks up the liquid solution and defined droplets ensuring Atomic level

    00:07:40 mixing the water simply evaporates so there's no need to change the pH or to separate the solids from a liquid as dang notes you just let the gas go and you're left with the particles which is what you want with lithium included at the outset there's no need for mixing solids with solids which is neither efficient nor effective they could even control the

    00:08:00 structure or morphology of the particles that formed in one series of experiments they tried exposing the incoming spray to different rates of temperature change over time they found that the temperature history has a direct impact on morphology with no preheating the particles burst apart and with rapid preheating the particles were Hollow the best outcomes came when they used

    00:08:21 temperatures ranging from 175 degrees Celsius to 225 degrees Celsius experiments with coin cell batteries laboratory devices used for testing battery materials confirms that by adjusting the preheating temperature they could achieve a particle morphology that would optimize the performance of their materials best of all the particles formed in

    00:08:42 seconds assuming the time needed for conventional annealing and de-agglomerating the new setup could synthesize the finished cathode material in half the total time needed for co-precipitation moreover the first stage of the co-precipitation system is replaced by a far simpler setup a savings in capital costs we were very happy sistang but then we thought if

    00:09:05 we've changed the precursor side so the lithium is mixed well with the salts do we need to have the same process for the second stage maybe not improving the second stage the key time and energy consuming step in the second stage is the annealing in today's co-precipitation process the strategy is to anneal at a low temperature for a long time giving the

    00:09:28 operator time to manipulate and control the process but running a furnace for some 20 hours even at a low temperature consumes a lot of energy based on their studies thus far Deng thought what if we slightly increase the temperature but reduce the annealing time by orders of magnitude then we could cut energy consumption and we might still achieve the desired crystal

    00:09:49 structure however experiments at slightly elevated temperatures and short treatment times didn't bring the results they had hoped for in transmission electron microscope tem images the particles that form take clouds of light looking nanoscale particles attached their surfaces when the researchers perform the same experiments without adding the lithium

    00:10:10 those nanoparticles didn't appear based on that and other tests they concluded that the nanoparticles were pure lithium so it seems like long duration annealing would be needed to ensure that the lithium made its way inside the particles but then they came up with a different solution to the lithium distribution problem they added a small amount just

    00:10:29 one percent by weight of an inexpensive compound called urea to their mixture in tem images of the particles formed the undesirable nanoparticles were largely gone to Stang experiments in the laboratory coin cells show that the addition of urea significantly altered the response to changes in the annealing temperature when the urea was absent raising the annealing temperature led to

    00:10:51 a dramatic decline in performance of the cathode material that formed but with the urea present the performance of the material that formed was unaffected by any temperature change that result meant that as long as the urea was added with the other precursors they could push up the temperature shrink the annealing time and omit the gradual ramp up and cool down process

    00:11:12 further Imaging studies confirmed that their approach yields the desired crystal structure and the homogeneous Elemental distribution of the Cobalt nickel manganese and lithium within the particles moreover and tests of various performance measures their materials did as well as materials produced by co-precipitation or by other methods using long-time heat treatment indeed

    00:11:34 the performance was comparable to that of commercial batteries with cathodes made of ncm-811 so now the long and expensive second stage required in standard co-precipitation could be replaced by just 20 minutes of annealing at about 870 degrees Celsius plus 20 minutes of cooling down at room temperature Theory continuing work and planning for

    00:11:54 scale up while experimental evidence supports their approach Deng and her group are now working to understand why it works getting the underlying physics right will help us design the process to control the morphology and to scale up the process system and they have a hypothesis for why the lithium nanoparticles in their flame synthesis

    00:12:14 process end up on the surfaces of the larger particles and why the presence of urea solves that problem according to their Theory without the added urea the metal and lithium items are initially well mixed within the droplet but as heating progresses the lithium diffuses to the surface and ends up as nanoparticles attach the solidified particle as a result a long

    00:12:36 annealing process is needed to move the lithium in among the other atoms when the urea is present it starts out mixed with the lithium and other atoms inside the droplet as temperatures rise the urea decomposes forming Bubbles as heating progresses the bubbles burst increasing circulation which keeps the lithium from diffusing to the surface the lithium ends up uniformly

    00:12:58 distributed so the final heat treatment can be very short the researchers are now designing a system to suspend a droplet of their mixture so they can observe the circulation inside it with and without the urea present they're also developing experiments to examine how droplets vaporize employing tools and methods they have used in the past to study how hydrocarbons vaporize

    00:13:19 inside internal combustion and agents they also have ideas about how to streamline and scale up their process in co-precipitation the first stage takes 10 to 20 hours so one batch at a time moves on to the second stage to be annealed in contrast the novel fast process generates particles in 20 minutes or less a rate that's consistent with continuous processing

    00:13:41 and they're designed for an integrated synthesis system the particles coming out of the back house are deposited on a belt that carries them for 10 or 20 minutes through a furnace a deglomerator then breaks any attached particles apart and the cathode powder emerges ready to be fabricated into a high performance cathode for a Lithium-Ion battery the cathode powders for high performance

    00:14:03 Lithium-ion batteries would thus be manufactured at unprecedented speed low cost and low energy use Deng notes that every component in their integrated system is already used in industry generally at a large scale and high flow through rate that's why we see great potential for our technology to be commercialized and scaled up she says where expertise comes into play is in

    00:14:24 designing the combustion chamber to control the temperature and heating rate so as to produce particles with a desired morphology and while a detailed economic analysis has yet to be performed it seems clear that their technique will be faster the equipment simpler and the energy use lower than other methods of manufacturing cathode materials for Lithium-ion batteries

    00:14:43 potentially a major contribution to the ongoing energy transition This research was supported by the MIT Department of mechanical engineering foreign foreign foreign