Battery startups are sparking lots of interest from investors these days.

Seeo, based in Berkeley, Calif., has raised $8.6 million while CFX Battery has snagged $5 million, according to their filings with the Securities and Exchange Commission this week.

Both companies are on the quest for the perfect lithium chemistries to make batteries that can hold lots of energy and are cheap to make and safe to use.

With multibillion-dollar investments from the federal government for automotive and other advanced battery research and manufacturing, it's easy to see why venture capitalists would be looking to put money in battery startups.

Some of the high-flying startups that have attracted lots of private equity include A123 Systems and Boston-Power. A123 Systems recently won a $249.1 million grant from U.S. Department of Energy to build factories in Michigan for components production and car battery pack assembly.

Seeo sought a smaller round than CFX. Seeo offered $8.86 million of shares for sale earlier this month and got $8.6 million. CFX offered $26.95 million around the same time and got $5 million so far.

Seeo is developing solid electrolytes for lithium polymer batteries, technology that came from the Lawrence Berkeley National Laboratory. The company has been relatively quiet about what it's up to.

CFX, meanwhile, is a company founded in 2007 that previously raised $11 million from investors including CMEA Ventures, Harris & Harris Group and U.S. Venture Partners.

The company is developing lithium carbon-fluoride based batteries for the auto, consumer electronics, medical and military markets.

CFX's co-founders include Robert Grubbs, a professor at the California Institute of Technology and a 2005 Nobel Prize winner in chemistry; and Rachid Yazami, a professor from the French National Center of Scientific Research (CNRS).  

The company moved into a 16,000-square-foot office and lab in Azusa last December.

Lithium carbon-fluoride battery has high energy density, so it can hold a lot of energy. It also has long shelf life and is considered safe. But it can be expensive compared with other types of lithium batteries, and it does do so well in cold temperatures.

The company has figured out ways to boost performance and lowering production costs, including the use multi-walled carbon nanotubes to improve conductivity, according to market research firm Frost & Sullivan, which named the company the emerging battery startup of the year in 2008. 

The startup's first product would be a primary battery, though it also plans to introduce rechargeable versions later.

Given the potentially large market for electric cars, a host of tech giants are joining the race to develop the idea batteries.

IBM, for example, is big on lithium-air batteries, which produces energy by exposing metal and an electrolyte to oxygen. The company touted its development at its Almaden lab near San Jose, Calif., this week (see photo of a battery with concept car).

Other major players include Korea-based LG Chem, which snagged the contract to sell lithium-ion batteries for the Chevy Volt.