Envia Systems, which has created a cathode that it claims can more than double the capacity of lithium-ion batteries, has raised $17 million in a new round, and $7 million of the total comes from General Motors.

The new round of investment underscores the ongoing interest of VCs and large corporations in energystorage Besides GM, Asahi Glass and Asahi Kahei invested in the company. But the additional investment is also an endorsement of Envia's somewhat unusual business model.

Envia doesn't want to make batteries. Instead, it aspires only to make the cathode, a crucial internal component, and to license its intellectual property. Making battery cells or battery packs remains a high-risk, capital-intensive endeavor that requires scientific creativity and engineering breakthroughs. Most companies fail in the early stages, and even if a startup gets that far, it then has to contend with giants like LG and Toshiba that have extensive R&D teams, worldwide sales channels, strong links with government officials, friends at car companies (they already sell chips to automakers), and factory capacity that could cover several football fields.

Capacitors requires far less capital investment. Besides, doesn't selling components based around novel intellectual property to other, larger, brand name manufacturers work in semiconductors? Consumers never buy Cypress Semiconductor products, after all. They buy set-top boxes with Cypress chips inside them.

"It's going to happen," CEO Sujeet Kumar told me last year.

Sadly, in batteries, it doesn't work so easily. See the story on Envia from last year. Large Asian conglomerates are much more reluctant to license crucial technology from startups. Some of the companies are also far more reluctant to acquire startups and integrate their technology into existing product lines. At many companies, the not-invented-here mindset remains a corporate ethos.

Plus, they fear losing a competitive advantage. Batteries, unlike computers, function more like holistic machines: the components are fine-tuned and finessed to work together. Many say the cathode determines the personality of a lithium-ion battery. Trying to integrate a third-party component could be a step backward, and what happens if other large rivals adopt the same cathode?

Some companies might be able to sell passive components like separators to battery makers, but VCs we talked to last year said selling cathodes looked like a stiff, uphill battle.

GM helps. No battery maker will refuse to work with Envia if GM says that it really, really wants to make its next EV with batteries containing its cathode. Kumar has also said that Chinese battery makers are interested. They are a little further behind that manufacturers in South Korea and Japan. And, interestingly, China is lot more open to new ideas than Western companies. Innovalight, which makes a pixie dust that increases the efficiency of solar panels, has five customers, all Chinese. Tigo Energy, which makes DC optimizers for solar panels, is getting a lot of interest from China.

A few other startups seem to be taking a component approach. PolyPlus in Berkeley, Calif., has come up with a solid electrolyte and other technologies that might make it possible to mass-manufacture lithium air batteries, a futuristic unit that could hold ten times as much power as today's batteries. The company also has a lithium sulfur battery it will license.

Porous Power Technologies has created a way to coat electrodes in batteries with a spray-on separator for lithium-ion batteries. A spray-on separator can increase the capacity of batteries, cut the manufacturing cost and increase the reliability, says CEO Tim Feaver.

Meanwhile, a few startups like Zeptor -- not the evil galactic dictator from the Antares galaxy, but a group of engineers out of the greentech grad school known as Intel -- are experimenting with cathodes made from carbon nanotubes. And then there are companies like Atievo, which make software for controlling and monitoring battery cells stuffed by the hundreds into car battery packs.