Portrait picture of Sarah Fleischer

TUM Alumna Sarah Fleischer is the founder of the company tozero (Image: tozero).

Alumni in sustainability
Entrepreneur Sarah Fleischer
“Founding Is Easy, but Persevering Is Difficult”
22. Mar 2024  |  
Reading time Min.
Lithium is scarcely found in Europe, but it is urgently needed for the energy transition. This is a problem that TUM Alumna Sarah Fleischer aims to solve with her startup. Tozero is one of the first companies in Europe to recycle lithium-ion batteries. Even Federal Chancellor Olaf Scholz is interested in the company of the young founder.
In a commercial area in Karlsfeld near Munich, a container with a mason jar-like appearance sits on an office desk, complete with a red-and-white checkered lid. However, it doesn’t contain homemade jam but rather lithium. Revolutionary lithium. Recycled lithium. Sarah Fleischer calls it “White Gold – made with love in Munich.”

The TUM Alumna is one of the founders of tozero, one of the first startups in Europe for recycling lithium-ion batteries, a technology that even Federal Chancellor Olaf Scholz finds intriguing. The reason: lithium is becoming one of the most crucial commodities in the world, more important than oil and gas, yet it is scarcely found in Europe. And without lithium, it becomes challenging with smartphones and the energy transition, with electric cars and solar panels. There is a lack of mining areas and efficient technology to recover high-quality lithium from old batteries.

Tozero aims to be the European solution to this lithium problem. For founder Sarah Fleischer, however, the company is also the answer to the question: “Can I endure another failure?”

Porträtbild von Sarah Fleischer und Dr. Ksenija Neumann.
Sarah Fleischer and her co-founder Dr. Ksenija Milicevic Neumann at the tozero Day celebration: The one-year anniversary of tozero. (Image: tozero)

Tozero is Sarah Fleischer’s third venture. After completing her bachelor’s degree in Mechanical Engineering, the TUM Alumna founded her first startup: an online shop for German baby products in China. A year later, she started a service company that facilitated luxury goods for Chinese tourists in Europe. Both startups failed. The first one due to diverging visions between Sarah Fleischer and her co-founder, and the second due to insufficient funding. “After that, I fell into a deep hole because failure is very challenging in German society,” says Sarah Fleischer today.

For almost six years, she therefore initially rejected new entrepreneurial offers. The next time around, it had to be worth it, there had to be meaning behind the project, not just money: “Starting a business is easy. Holding on, going through the ups and downs, that’s the hard part,” explains the TUM Alumna.

So, Sarah Fleischer first focused on completing her master’s degree in Mechanical Engineering at TUM. However, her commitment to innovative projects persisted. During her studies, she participated in a student team that competed in Elon Musk’s student competition, the ‘Hyperloop Pod Competition’. As the only German group, they made it among the top thirty. Confidence slowly returned, and a few years later, an encounter encouraged her to fully revive her entrepreneurial spirit.

Creating Something New out of Nothing Is Simply Incredible.

Sarah Fleischer


In March 2019, Sarah Fleischer was working as a consultant for the Luxembourg Space Agency (LSA) when she met Dr. Ksenija Milicevic Neumann at a social networking dinner. That same evening, the two women signed a contract on a napkin promising that they would eventually start a venture together: “We will conquer the universe together,” it said.

Three years later, Sarah Fleischer received a phone call. Ksenija Milicevic Neumann, who was researching the foundational principles for tozero’s later recycling technology at RWTH Aachen, was on the line, saying, “Hey Sarah, you’re obligated to start a venture with me, in case you’ve forgotten, a scan of the napkin is in your inbox.” For six months, the two of them tinkered with the startup idea for tozero alongside their full-time jobs, figuring out if their visions aligned, and planning the financing round.

Sarah Fleischer realized that tozero could be something she could finally say yes to. Something that aligned with her roots as a mechanical engineer. Something for which failure would be worth it again because it could potentially change the world for the better. “The biggest hurdle for female founders is having the courage to do something crazy, even when you’re afraid or think you’re not ready yet,” says Sarah Fleischer.

Bild: tozero.

As CEO of tozero, Sarah Fleischer was invited by Olaf Scholz in February 2024 to be a keynote speaker at the fourth meeting of the Alliance for Transformation – a dialogue format where the German government convenes with business, social partners, and academia to discuss how the socio-ecological transformation can succeed in Germany. During the subsequent event series “Workshop of Change,” she also met Federal President Frank-Walter Steinmeier (Image: tozero).

The first job interviews for their company were held by the two founders in the free offices of the Munich Urban Colab at UnternehmerTUM in Munich’s creative quarter. By now, seventeen people from ten different countries work at tozero. A map hangs at the entrance of the office, displaying pins to illustrate how international the team is: USA, Canada, Turkey, France, several Scandinavian countries. “We have people from almost every continent working with us,” says Sarah Fleischer.

Thinking internationally, having different perspectives, has always been important to Fleischer. She graduated from the German School Shanghai, wrote her bachelor’s thesis at a university in Oman, her master’s thesis at Harvard Business School in the USA, and at TUM, she led the German-Chinese Alumni Club, connecting students with companies and organizing Chinese New Year celebrations. “My group at TUM was already completely international and diverse back then, and I wanted the same for my team,” she says.


Many employees of tozero have relocated to Munich, specifically to Sauerlach. In March 2023, the first prototype plant was established there after the founders raised €3.5 million for their startup in their initial funding round. The 100-square-meter production hall became too small within just two months. Now, tozero is located in Karlsfeld and operates in a larger facility, producing secondary lithium.

Here, batteries are recycled and lithium, nickel, cobalt, manganese, and graphite are extracted. Before visiting this hall, Sarah Fleischer sits in a white lab coat, safety goggles, helmet, and gloves in the changing room lined with green artificial turf and light wood. She pulls on shoe covers and says, “Being able to create something new out of nothing is simply incredible.”

TUM Alumna Sarah Fleischer

Sarah Fleischer (Bild: tozero)

Sarah Fleischer

Bachelor Mechanical Engineering 2014, Master 2019


Sarah Fleischer earned her bachelor’s and master’s degrees in Mechanical Engineering from TUM, where she also led the German-Chinese Alumni Club. She is a Fellow of the Center for Digital Technology and Management (CDTM) – a joint research and teaching institute of TUM and LMU. She wrote her master’s thesis at Harvard Business School.

Together with Dr. Ksenija Milicevic Neumann, Sarah Fleischer founded tozero in 2023: Europe’s first startup to recycle lithium-ion batteries. Through the recycling process, all critical materials contained in the battery, such as lithium, graphite, nickel, and cobalt, are sustainably recovered. The founders raised €3.5 million in the first pre-seed financing round for the startup, enabling them to build an initial prototype plant in Munich.

Before founding tozero, Sarah Fleischer served as the lead for commercial strategy and partnerships at the German logistics startup Forto. Prior to that, she was a consultant for the Luxembourg Space Agency, where she established the €120 million early-stage VC fund Orbital Ventures and introduced the ESRIC Incubator for startups in collaboration with the European Space Agency (ESA).

Sarah Fleischer also shares her experiences as a mentor in the TUM Mentoring program, where alumni mentor students. In April 2024, she will speak at the event commemorating the 15th anniversary of the Women of TUM network. The network comprises over 19,000 female students, 130 female professors, and 40,000 alumnae.