Leading the charge to better batteries

Princeton University, Engineering School

Facebook

XLinkedInWeChatBlueskyMessageWhatsAppEmail

 

image: 

Professor Kelsey Hatzell and postdoctoral researcher Se Hwan Park stand in the Hatzell lab. (Photo by Bumper DeJesus)

view more 

Credit: Bumper DeJesus, Andlinger Center for Energy and the Environment

From laptops to electric vehicles, lithium-ion batteries power everyday life. However, as demand for longer-lasting devices threatens to outstrip the energy that lithium-ion supplies, researchers are on the hunt for more powerful batteries.

A team led by Kelsey Hatzell, an associate professor of mechanical and aerospace engineering and the Andlinger Center for Energy and the Environment, has uncovered insights that could help power a new type of battery, called an anode-free solid-state battery, past lithium-ion’s limitations.

By understanding how these advanced solid-state batteries operate and fail under different conditions, Hatzell’s research is informing efforts to improve their performance and manufacturability, helping them to move from the lab to the real world to support the clean energy transition.

“If we can successfully introduce these up-and-coming batteries, we can access energy densities that are impossible with conventional batteries,” said Hatzell. “It would mean that your laptop and your phone would last longer on a charge. It could allow electric vehicles to hit over 500 miles on a charge. It could even move us toward feats that seem impossible today, like electrified aviation.”

The papers stem from Hatzell’s involvement as the manufacturing leader for Mechano-Chemical Understanding of Solid Ion Conductors (MUSIC), an Energy Research Frontier Center supported by the U.S. Department of Energy whose members are unlocking fundamental insight to advance electrochemical energy storage systems. MUSIC is led by the University of Michigan at Ann Arbor and encompasses 16 faculty members from across nine institutions, including Princeton University.

"Solid-state batteries can revolutionize energy storage technology, but a significant challenge is developing a process for manufacturing them at scale," said energy storage expert Jeff Sakamoto, director of MUSIC and a professor of materials and mechanical engineering at the University of California-Santa Barbara. “Hatzell’s work is playing an important role in improving the solid-state manufacturing process, and her work with MUSIC is an example of how integrated research approaches can help overcome complex, multidisciplinary challenges.”

Batteries: A look under the hood

Conventionally, batteries feature two electrodes — one positive (commonly called the cathode) and one negative (the anode). Each electrode is paired with a thin metal foil called a current collector that connects the battery to the external circuit, and the two electrodes are separated from one another by an electrolyte.

The movement of ions between the two electrodes powers the battery. When the battery charges, ions flow from the positive electrode, through the electrolyte, and to the negative electrode. When the battery is discharged, the flow of ions reverses directions.

Compared to the familiar lithium-ion battery, the batteries that Hatzell and her group study are different at two fundamental levels.

First, while the electrolyte in lithium-ion batteries is a liquid, the electrolyte in a solid-state battery is — as its name implies — a solid.

The difference is significant. Solid-state batteries can store more energy in less space than lithium-ion batteries, opening the door to longer driving ranges for electric vehicles. They can also operate with high performance at a wider range of temperatures and promise greater durability than their lithium-ion counterparts.

Second, the batteries that Hatzell studies are ‘anode-free,’ meaning that the negative electrode has been removed. Instead, ions flow from the positive cathode directly to the current collector at the opposite end of the battery. The ions then plate onto the current collector itself, forming a thin metal layer as the battery charges.

Removing the anode makes the battery cheaper and even more compact than standard solid-state batteries. At the same time, anode-free solid-state batteries avoid a major bottleneck to deployment compared to standard solid-state batteries, as the anode in most solid-state batteries is a lithium metal foil that requires specialized manufacturing approaches.

“If you could assemble a battery without a lithium metal anode, you would greatly cut costs while leveraging existing manufacturing processes,” Hatzell said. “Both of these advantages are key if you want to make a dent in the battery market.”

Cracking under pressure

While these next-generation batteries sound good on paper, they face many challenges in practice. Foremost among those is ensuring good contact between the solid electrolyte and the current collector. This ensures that as the ions travel through the electrolyte, they evenly deposit on the current collector when the battery is charged and evenly strip from the current collector when it is discharged.

In one paper, published Feb. 22 in ACS Energy Letters, Hatzell and first-author Se Hwan Park, a postdoctoral researcher in her group, explored how factors such as the pressure applied to the battery influence the contact between the electrolyte and the current collector.

“During charging and discharging, the battery is undergoing an electrochemical reaction. By applying an external pressure, we’re also introducing mechanical forces,” said Park. “It’s a very complex system, with many interacting forces.”

Unlike the liquid electrolytes in traditional batteries that can easily change shape, solid electrolytes are rigid. As such, any defects or irregularities on the surface of either the electrolyte or the current collector in a solid-state battery negatively impact the quality of contact between the two components.

The team found that applying low pressures to the system did not do enough to improve the uneven contact caused by those surface irregularities, resulting in ions plating and stripping unevenly on the current collector as the battery was charged and discharged. Areas with good contact became hotspots, while areas with poor contact formed voids. Ultimately, the uneven plating led to the formation of sharp metal filaments that, like tiny needles, could pierce the solid electrolyte and cause the battery to short-circuit.

At high pressures, the researchers encountered a different problem. While they found that higher pressures favored better contact and more uniform plating and stripping, the high pressure forced the electrolyte and the current collector together so intensely that any imperfections on either were magnified until the mechanical stress caused fractures to form.

Thus, low and high pressure caused the batteries to fail, but for different reasons — either too little or too much contact between the electrolyte and current collector. Hatzell said both failure modes give new insight into the best ways to make and operate anode-free solid-state batteries.

“The Holy Grail in this area will be to figure out how to maintain solid contact at low pressures, since manufacturing a defect-free electrolyte is practically impossible,” Hatzell said. “If we want to realize the potential of these batteries, we have to solve the contact issue.”

A silver lining

While the results of their work highlighted the importance of even contact between the electrolyte and current collector, a second paper from Hatzell’s group, published Dec. 19 in Advanced Energy Materials, investigated a way to achieve that contact.

In this paper, the researchers demonstrated it was possible to achieve more uniform ion plating and stripping by applying a thin coating between the current collector and the electrolyte to facilitate better ion transport.

In their work, the researchers tested several of these coatings, called interlayers, to study how their structure and composition impacted how ions were plated while the battery charged.

Aligning with previous research, the team found that interlayers made from carbon and silver nanoparticles were best at achieving a uniform metal deposition. The silver in these interlayers formed alloys with ions during battery charge and discharge, enabling even plating and stripping from the current collector.

However, the team found that the size of the silver nanoparticles matters. Interlayers with larger, 200-nanometer silver particles formed spindly, uneven metal structures on the current collector. These wire-like structures made the battery less durable, leading to reduced capacity and eventual battery failure over several charging cycles.

Interlayers with smaller, 50-nanometer silver particles supported denser and more uniform structures, leading to batteries with greater stability and higher power output.

“Only a few groups have investigated the actual processes that occur in these interlayers,” said Park. “Among other findings, we demonstrated that the stability of these systems is linked to the morphology of the metal as it plates and strips from the current collector.”

The difference, Park explained, boils down to the alloying process, which causes the silver particles in the interlayer to expand. This expansion leads to localized stress that can alter the interlayer’s structure, forming and expanding pores that impede the flow of ions. When the nanoparticles were smaller and thus better dispersed, the stress was more evenly distributed across the interlayer.

“These findings can inform the strategy for fabricating these interlayers,” Park said. “By reducing the size of the silver particles, we can make sure that we only get the advantages of the silver in the interlayer, which, in turn, could allow us to achieve good contact and uniform plating even at low pressures.”

Charging into the future

In addition to her group’s experimental work, Hatzell and several MUSIC collaborators reviewed the current state of anode-free solid-state batteries in a paper published Jan. 2 in Nature Materials, summarizing recent progress and identifying outstanding research gaps.

One of the biggest gaps in battery research, Park and Hatzell agreed, is demonstrating whether successful techniques in the lab can be scaled and incorporated into the existing battery manufacturing supply chain. There, too, they are hopeful.

After solid-state batteries have been promised as the future of energy storage for several years, Hatzell said that countries like China, Japan, and South Korea now have near-term plans to bring solid-state batteries to market. Samsung, for example, has vowed to begin mass-producing solid-state batteries by 2027, and Toyota has a mass production target of 2030.

 “The challenge will be getting from research to the real world in only a few years,” said Hatzell. “Hopefully the work we’re doing now at MUSIC can underpin the development and deployment of these next-generation batteries at a meaningfully large scale.”

Battery research device

A device built to measure the effects of pressure on a battery system. (Photo by Bumper DeJesus)

Credit

Bumper DeJesus, Andlinger Center for Energy and the Environment

---

The paper, “Filament-induced failure in Li-free solid-state batteries,” was published February 22, 2025 in ACS Energy Letters. In addition to Park and Hatzell, co-authors include Abhinand Ayyaswamy, Bairav Vishnugopi, and Partha Mukherjee of Purdue University; Jonathan Gjerde, W. Beck Andrews, and Katsuyo Thornton of University of Michigan, Ann Arbor; and Michael Drakopoulos, Nghia Vo, and Zhong Zhong of Brookhaven National Laboratory. The work was supported by the MUSIC Energy Frontier Research Center, funded by the Department of Energy.

The paper, “Lithium kinetics in Ag-C porous interlayer in reservoir-free solid-state batteries,” was published December 19, 2024 in Advanced Energy Materials. In addition to Park and Hatzell, co-authors include Kaustubh Naik, Bairav Vishnugopi, and Partha Mukherjee of Purdue University. The work was supported by the MUSIC Energy Frontier Research Center, funded by the Department of Energy.

The perspective paper, “Electro-chemo-mechanics of ‘anode-free’ solid-state batteries,” was published January 2, 2025 in Nature Materials, with Stephanie Elizabeth Sandoval of Georgia Institute of Technology and Catherine Haslam of University of Michigan, Ann Arbor as co-first authors and Matthew McDowell of Georgia Institute of Technology as corresponding author. Including Park and Hatzell, the paper’s co-authors are Bairav Vishnugopi and Partha Mukherjee of Purdue University; Daniel Liao, Jeong Seop Yoon, and Neil Dasgupta of University of Michigan, Ann Arbor; Jeff Sakamoto of University of Michigan, Ann Arbor and University of California, Santa Barbara; and Yixian Wang, David Mitlin, and Donald Siegel of The University of Texas at Austin. The work was supported by the MUSIC Energy Frontier Research Center, funded by the Department of Energy.

---

Journal

ACS Energy Letters

DOI

10.1021/acsenergylett.5c00004 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Filament-Induced Failure in Lithium-Reservoir-Free Solid-State Batteries

Article Publication Date

27-Feb-2025

 

Self-driving cars learn to share road knowledge through digital word-of-mouth

NYU Tandon-led research team develops system that lets vehicles pass along AI models like messages in a social network, even when they don't meet directly

NYU Tandon School of Engineering

Facebook

XLinkedInWeChatBlueskyMessageWhatsAppEmail

An NYU Tandon School of Engineering-led research team has developed a way for self-driving vehicles to share their knowledge about road conditions indirectly, making it possible for each vehicle to learn from the experiences of others even when they rarely meet on the road.

The research, presented in a paper at the Association for the Advancement of Artificial Intelligence Conference on February 27, 2025, tackles a persistent problem in artificial intelligence: how to help vehicles learn from each other while keeping their data private. Typically, vehicles only share what they have learned during brief direct encounters, limiting how quickly they can adapt to new conditions.

"Think of it like creating a network of shared experiences for self-driving cars," said Yong Liu, who supervised the research led by his Ph.D. student Xiaoyu Wang. Liu is a professor in NYU Tandon’s Electrical and Computer Engineering Department and a member of its Center for Advanced Technology in Telecommunications and Distributed Information Systems and of NYU WIRELESS.

"A car that has only driven in Manhattan could now learn about road conditions in Brooklyn from other vehicles, even if it never drives there itself. This would make every vehicle smarter and better prepared for situations it hasn't personally encountered,” Liu said.

The researchers call their new approach Cached Decentralized Federated Learning (Cached-DFL). Unlike traditional Federated Learning, which relies on a central server to coordinate updates, Cached-DFL enables vehicles to train their own AI models locally and share those models with others directly.

When vehicles come within 100 meters of each other, they use high-speed device-to-device communication to exchange trained models rather than raw data. Crucially, they can also pass along models they’ve received from previous encounters, allowing information to spread far beyond immediate interactions. Each vehicle maintains a cache of up to 10 external models and updates its AI every 120 seconds.

To prevent outdated information from degrading performance, the system automatically removes older models based on a staleness threshold, ensuring that vehicles prioritize recent and relevant knowledge.

The researchers tested their system through computer simulations using Manhattan’s street layout as a template. In their experiments, virtual vehicles moved along the city’s grid at about 14 meters per second, making turns at intersections based on probability, with a 50% chance of continuing straight and equal odds of turning onto other available roads.

Unlike conventional decentralized learning methods, which suffer when vehicles don’t meet frequently, Cached-DFL allows models to travel indirectly through the network, much like how messages spread in delay-tolerant networks, which are designed to handle intermittent connectivity by storing and forwarding data until a connection is available. By acting as relays, vehicles can pass along knowledge even if they never personally experience certain conditions.

"It's a bit like how information spreads in social networks," explained Liu. "Devices can now pass along knowledge from others they've met, even if those devices never directly encounter each other."

This multi-hop transfer mechanism reduces the limitations of traditional model-sharing approaches, which rely on immediate, one-to-one exchanges. By allowing vehicles to act as relays, Cached-DFL enables learning to propagate across an entire fleet more efficiently than if each vehicle were limited to direct interactions alone.

The technology allows connected vehicles to learn about road conditions, signals, and obstacles while keeping data private. This is especially useful in cities where cars face varied conditions but rarely meet long enough for traditional learning methods.

The study shows that vehicle speed, cache size, and model expiration impact learning efficiency. Faster speeds and frequent communication improve results, while outdated models reduce accuracy. A group-based caching strategy further enhances learning by prioritizing diverse models from different areas rather than just the latest ones.

As AI moves from centralized servers to edge devices, Cached-DFL provides a secure and efficient way for self-driving cars to learn collectively, making them smarter and more adaptive. Cached-DFL can also be applied to other networked systems of smart mobile agents, such as drones, robots and satellites, for robust and efficient decentralized learning towards achieving swarm intelligence.

The researchers have made their code publicly available. More detail can be found in their technical report.  In addition to Liu and Wang, the research team consists of Guojun Xiong and Jian Li of Stony Brook University; and Houwei Cao of New York Institute of Technology.

The research was supported by multiple National Science Foundation grants, the Resilient & Intelligent NextG Systems (RINGS) program — which includes funding from the Department of Defense and the National Institute of Standards and Technology — and NYU’s computing resources.

---

DOI

10.48550/arXiv.2408.14001 

Roadway safety research, automated vehicle testing join forces at U-M

As the U-M Transportation Research Institute turns 60, it expands to include Mcity and fast-track AV technologies as the next frontier in roadway safety

University of Michigan

Facebook

XLinkedInWeChatBlueskyMessageWhatsAppEmail

 

 

Images

 

In an effort to bolster its research on next-generation mobility technologies that save lives, the University of Michigan is fusing its longstanding leadership in transportation safety with its distinct expertise in testing connected and automated vehicle technologies.

 

Beginning March 1, U-M's Transportation Research Institute (UMTRI) will expand to include the Mcity public/private partnership and test facility. Henry Liu, Mcity's director since 2022, will lead the expanded UMTRI.

 

"We see this as a multiplier of our impact," said Liu, the Bruce D. Greenshields Collegiate Professor of Engineering and a professor of civil and environmental engineering. "UMTRI brings top safety researchers and a focus on the human facets, while Mcity provides technology development and a one-of-a-kind test facility. Together they've shaped Michigan Engineering's reputation as a leader in mobility work that not only advances the engineering aspects, but goes beyond to examine how they impact peoples' lives."

 

Liu takes over for James Sayer, UMTRI's director for the past nine years, who will remain as a research scientist. 

 

The change is a homecoming of sorts for the Mcity Test Facility. UMTRI leaders including Sayer—along with industry and government partners—envisioned, developed and launched Mcity in 2015 as the world's first purpose-built test track for connected and automated vehicles. 

 

"What spun out of our efforts to improve roadway safety has come full circle, and at a time when it's clear that connected and automated vehicle technologies are the essential next frontier in traffic safety," Sayer said. "More than 40,000 people are still dying on U.S. roads every year."

 

The new era begins as UMTRI marks its 60th anniversary and the Mcity Test Facility its 10th.

 

Sixty years of saving lives 

 

In 1965, the nation was facing an alarming rise in traffic fatalities. More Americans were owning faster cars designed for style and performance, and cruising them along the new interstate highways built the previous decade. From 1960-65, roadway deaths rose by 20% per 100,000 people, according to data from the National Safety Council. 

 

The federal government recognized the issue and began deliberating solutions. So did Ford, GM and the Automobile Manufacturers Association. With $10 million, they founded UMTRI's predecessor, the Highway Safety Research Institute, which became UMTRI in the 1980s. It was time to add safety to vehicle engineering.

 

Since opening its doors, the institute has conducted foundational research that played a pivotal role in bringing fatalities down by an estimated 35% per capita, according to 2023 NRC data. Most recently, UMTRI has led connected and automated vehicle deployments that enabled it to amass the world's largest set of connected vehicle data, and use it to demonstrate how effective the tech can be at enhancing safety. But its work started with a focus on vehicle design, driver behavior, vehicle dynamics and crash analysis.

 

During the 1970s, researchers began work to make crash test dummies more realistic to better protect people in cars, including children. Eventually they published a landmark study of driver body shape and posture, Anthropometry of Motor Vehicle Occupants, that has served as the design basis for adult-sized crash test dummies for nearly 40 years. The work continues today.

 

In the following decade, the institute's research shaped design and policy around occupant restraint systems, particularly seatbelts, child safety seats and airbag technologies. As one example, a 1988 survey of child safety seat use and misuse across Michigan drew national attention and led to the creation of the Lower Anchors and Tethers for Children (LATCH) system for installing child safety seats.

 

Around the same time, UMTRI and its researchers established the International Roughness Index used across the world by builders to quantify road surface quality. The index continues to play a critical role in road safety and reducing vehicle repair costs.

 

Today's heavy truck safety standards can also trace their origin to UMTRI researchers' mathematical modeling and measurements. 

 

By the 1990s, UMTRI had honed its advanced 3D modelling and simulation capabilities through decades of studying and validating vehicle dynamics, and startup Mechanical Simulation Corp. spun out to offer the auto industry a new way to accurately and realistically predict real-world vehicle behavior. When the company was purchased in 2022 by vehicle software supplier Applied Intuition, it supported more than 200 OEMs and Tier 1 suppliers. Today, Applied Intuition provides software used by automakers and others to advance autonomous vehicle technologies. It was valued at $6 billion in 2024.

 

UMTRI's record of safety work made it a natural partner for government and the auto industry as attention turned to the potential of connected and automated vehicles. Under UMTRI's leadership, roughly 2,800 drivers traveled 71 million miles in the world’s first large-scale connected vehicle deployment. Safety Pilot Model Deployment, a $30 million effort launched in 2012 with the U.S. Department of Transportation. 

 

Safety Pilot showed that connected vehicles can reduce unimpaired crashes by 80%. The initial project has evolved over the past decade with infrastructure and technology enhancements and now totals more than $82 million. Today's Ann Arbor Connected Environment 2.0 and Smart Intersections Project encompass 27 square miles of Ann Arbor, 75 sites, including 69 intersections and relies on cellular-based C-V2X. 

 

UMTRI's crash analysis research has continued to yield influential findings enabling an improved safety response. Partnering with the Office of Highway Safety Planning and others, including NHTSA, for more than 30 years, UMTRI has maintained high quality access to Michigan crash data statistics. The Michigan Traffic Crash Facts website is an award winning, powerful crash analysis tool that allows users to search traffic crash facts related to a wide-range of data including: age, deer, vehicle/driver and occupant information. 

 

The institute's work also includes the benefits of active safety systems such as automatic emergency braking, and it informed General Motors' decision to make five active safety features standard on most 2023 vehicles. This includes systems that reduce crashes involving pedestrians and cyclists. 

 

A safe place for technology testing

 

Early on, UMTRI leaders recognized the need to test cutting-edge connected and automated technologies in a safe environment, rather than on public roads. That's why they designed the Mcity Test Facility, a 32-acre site that recreates a real-world urban and suburban environment, complete with roads, intersections, traffic signs and signals, streetlights, building facades, sidewalks, construction obstacles and more. 

 

The goal of the test facility was to create a space for rigorous, repeatable testing in a safe, controlled environment and to complement UMTRI's large-scale real-world deployments. 

 

Automakers and others in the industry recognized the need to accelerate research and development of these technologies as well. Initially, 15 Leadership Circle companies pledged $1 million over three years, and 31 affiliate members $150,000, providing more than $19 million in industry support to operate the facility and fund research. Early Leadership Circle members included General Motors, Ford, Honda, State Farm, Toyota and Verizon. 

 

Not long after the Mcity Test Facility opened in 2015, Ford became the first automaker to test autonomous vehicles there.

 

"Testing Ford's autonomous vehicle fleet at Mcity provides another challenging, yet safe, urban environment to repeatedly check and hone these new technologies," Raj Nair, then Ford's group vice president of Global Product Development, said at the time. "This is an important step in making millions of people's lives better and improving their mobility."

 

By combining both physical and virtual assets, Mcity can recreate almost any driving scenario—controlling vehicle behavior, simulating pedestrians and more. Its researchers are also working to provide and advocate for an automated vehicle testing structure for the industry and consumers. Its Mcity Safety Assessment Program is a two-part protocol for validating the safety of Level 4 automated vehicles before real-world deployment that could serve as a blueprint for a national standard. L4 vehicles can navigate most driving situations without human intervention.

 

Mcity's Driverless Shuttle was the nation's first AV shuttle research project on user behavior and a way to gauge consumer acceptance of the technology. It was followed by partnerships with May Mobility on trial AV shuttle deployments in Ann Arbor and Detroit.

 

Today, Mcity offers remote testing too, made possible using digital infrastructure developed with funding from the National Science Foundation. The digital and physical infrastructure work together to allow researchers around the world to use the test facility without leaving home, helping to speed up development of automated technologies.

 

Also, Mcity recently introduced the first open-source digital twin of the test facility, providing a faster, safer, less expensive way to test autonomous and connected vehicle software. The digital twin is free for anybody to use and does not require a physical vehicle or test facility. 

 

A tipping point for road safety

 

Liu believes that bringing UMTRI and Mcity together has the potential to accelerate a tipping point for road safety. While traffic fatalities per 100,000 people are less than half of what they were at their worst in the 1970s—around 13 people vs. 28—more than 40,000 are still dying on U.S. roads every year. The USDOT calls it a "crisis" and has established the National Roadway Safety Strategy to address it. The strategy includes automated technologies, and Liu underscores their importance.

 

"Given all the safety features that have been added to vehicles over the years, it's my view that the only thing that will significantly reduce the number of roadway fatalities at this point is automation," Liu said. 

 

And not automation in a vacuum. 

 

"We need to think about how to protect AV occupants. Maybe the passengers shouldn't be facing forward. Maybe the seatbelts and airbags should be designed differently," Liu said. "In transportation, you really have to have a systems view, and this new structure will emphasize that."

AMERIKA

Medicaid extension policies that cover all immigrants in a post-COVID world reduce inequities in postpartum insurance coverage

Postpartum uninsurance declines by 4 percentage points; smaller impact among NYC’s Hispanic population

Columbia University's Mailman School of Public Health

Facebook

X
BlueskyMessageWhatsAppEmail

New York— A new study at Columbia University Mailman School of Public Health reveals that Medicaid extension policies, which cover all immigrants in the post-COVID era, have led to a notable reduction in postpartum uninsurance, particularly in New York City. However, the study highlights that awareness gaps may have hindered the full benefit for Hispanic immigrants. The results are published in the American Journal of Public Health (AJPH).

Continuous Medicaid enrollment during the Families First Coronavirus Response Act (FFCRA) was associated with a 4 percentage-point decrease in postpartum uninsurance among immigrant populations in New York City. This led to a reduction, though not complete elimination, of the insurance gap between immigrant and U.S.-born populations. An earlier study from Columbia Mailman School of Public Health conducted on a national scale revealed that continuous Medicaid coverage during the FFCRA period helped reduce uninsurance rates from 10 percent in 2019 to 3.7 percent  in 2021, with an increase in the use of preventive postpartum services among Medicaid beneficiaries.

“While postpartum Medicaid extension policies that include all immigrants help reduce inequities, it is still critical to implement community-based strategies to raise awareness of coverage and promote maternal health equity,” said Teresa Janevic, PhD, associate professor of Epidemiology at Columbia Mailman School.

The study examined postpartum insurance rates among Medicaid-paid births in New York City using the Pregnancy Risk Assessment Monitoring System (PRAMS). Researchers assessed uninsurance rates for individuals 2 to 6 months postpartum, comparing the pre-FFCRA period (2016-2019) with the post-FFCRA period (2020-2021). The analysis included 2,611 Medicaid-paid births in the pre-FFCRA period and 1,197 births from 2020 to 2021 post-FFCRA.

Among immigrant populations, postpartum uninsurance dropped from 13.6% to 9.3% following FFCRA, while the rate for U.S.-born individuals decreased from 1.2 percent to 0.7 percent  Although uninsurance decreased across all immigrant groups, the decline was least pronounced among Hispanic immigrants, who saw a reduction from 23.5 percent  to 18 percent. In fact, 1 in 6 Hispanic immigrants reported being uninsured during the FFCRA period despite continuing eligibility for coverage. Sociodemographic analyses showed differences in uninsurance based on years in the U.S., race/ethnicity, and education level.

In New York City, Hispanic and Black populations face 2- and 6-fold higher risks of pregnancy-related deaths, respectively, compared to non-Hispanic White populations. These inequities extend into the postpartum period, and the loss of Medicaid coverage after birth may contribute to these disparities.

“The finding that many Hispanic immigrants were unaware of their continued Medicaid coverage suggests that knowledge gaps about Medicaid eligibility—particularly related to immigration status—remain a critical barrier,” explained Janevic. “In 2020, postpartum maternal mortality rose by 41 perent during the COVID-19 pandemic, with the largest increase seen among Hispanic individuals. This underscores the urgent need to bridge these knowledge gaps.”

To address these challenges, the researchers suggest targeted communication strategies, such as partnering with community-based organizations and federally qualified health centers, to disseminate information about Medicaid coverage. However, these efforts may face challenges due to ongoing anti-immigrant sentiment in the U.S. and the fear some immigrant communities face accessing benefits for which they are eligible.

The study's results also carry national significance. Of the 47 states that extended postpartum Medicaid, New York and 11 other states include all enrollees, regardless of immigration status. The study shows that these states have made significant gains in improving postpartum insurance coverage. In contrast, states that exclude certain immigrant groups may not see similar benefits.

Co-authors of the study include Lauren Birnie, Kizzi Belfon, Lily Glenn, and Folake Eniola, New York City Department of Health and Mental Hygiene; Sheela Maru, Heeun Kim, and Ellerie Weber, Icahn School of Medicine at Mount Sinai; Simone Reynolds, SUNY Downstate Health Sciences University; and Ashley Fox, SUNY Albany Rockefeller College of Public Affairs and Policy.

The study was supported by the Robert Wood Johnson Foundation (grant #79625). The authors report no conflicts of interest.

Columbia University Mailman School of Public Health

Founded in 1922, the Columbia University Mailman School of Public Health pursues an agenda of research, education, and service to address the critical and complex public health issues affecting New Yorkers, the nation and the world. The Columbia Mailman School is the third largest recipient of NIH grants among schools of public health. Its nearly 300 multi-disciplinary faculty members work in more than 100 countries around the world, addressing such issues as preventing infectious and chronic diseases, environmental health, maternal and child health, health policy, climate change and health, and public health preparedness. It is a leader in public health education with more than 1,300 graduate students from 55 nations pursuing a variety of master’s and doctoral degree programs. The Columbia Mailman School is also home to numerous world-renowned research centers, including ICAP and the Center for Infection and Immunity. For more information, please visit www.mailman.columbia.edu.

---

Journal

American Journal of Public Health

Article Title

Immigrant inequities in uninsurance and postpartum Medicaid extension: a quasi-experimental study in New York City, 2016-2021