Murari
Ramkumar

A membrane is a doorman for ions. Murari Ramkumar builds the best doormen he can.

Inside a flow battery, an electrolyzer, a fuel cell, there is a sheet so thin you could mistake it for cling film. It lets the right ions through and blocks the wrong ones. Get it right and clean energy gets cheaper. Get it wrong and the whole device underperforms. That sheet is the entire business.

Most of the membrane industry solved the "let the right ions through" problem decades ago with fluorinated chemistry, the same family of "forever chemicals" now showing up in regulatory crosshairs around the world. Vimano's answer is different. Its membranes are PFAS-free, built from green-chemistry formulations tuned to the specific job: a flow battery storing the grid's surplus, an electrolyzer splitting water for hydrogen, a fuel cell pushing a truck a little further. Same platform, different recipe.

Murari Ramkumar founded the company in 2019 with Dr. Nagesh Kini, a materials scientist who had spent over a decade as a principal scientist at Thermax. Ramkumar brought a B.Tech from NIT Karnataka in Surathkal and a master's in nano science from the University of Pennsylvania, plus a research past that has very little to do with energy and everything to do with precision: at Penn he worked on neuroprosthetic devices and brain-computer interface fabrication, learning how to build tiny things that have to survive inside hostile environments. Membranes, it turns out, are also tiny things that have to survive inside hostile environments.

The pitch is not modest. Vimano wants its membrane inside one of every two large-scale energy storage devices, electrolyzers and fuel cells on the planet. It is the kind of number you say out loud to see if anyone laughs. So far, investors have written checks instead.

The hard part isn't inventing the membrane. It's making a big one.

When Ankur Capital first met the founders in 2020, the two were working out of a borrowed lab at the Indian Institute of Science, with one thing to show: a single membrane for redox flow batteries, roughly the size of a drink coaster. Plenty of materials work beautifully at 25 square centimeters and fall apart the moment you try to make them bigger. Scaling is where good chemistry goes to die.

Vimano scaled its membranes about 100x, from 25 cm² to 2,500 cm², and is pushing toward the meter-width rolls that real manufacturing demands. Along the way the company logged a string of firsts: India's first anion exchange membranes for electrolysis, and the first Make-in-India polymer films for satellite thermal management. That last one earned an early customer not usually associated with seed-stage startups: the Indian Space Research Organisation.

Three devices, one platform

The reason Vimano can chase such a big number with such a small team is that the underlying chemistry is a platform, not a product. A flow battery wants a membrane that stops the two electrolytes from mixing while keeping ions flowing - Vimano reports capacity retention 15.7x higher after 100 cycles. An AEM electrolyzer wants to split water cheaply enough that green hydrogen competes on price. A fuel cell wants range - a Vimano-equipped hydrogen cell reportedly adds about 35 km per 100 km of truck travel. Different recipes, same kitchen.

The seed money goes where seed money should: pilots with strategic partners, a bigger team, and the unglamorous work of turning a lab process into a manufacturing line. The membrane is invented. Now it has to become a product you can order by the meter.