New cell designs
 

Many batteries today contain a "gel" electrolyte. There is no free liquid inside the battery. The acid is contained in Absorbent Glass Mat (AGM) separators between the plates. The separators hold the acid much like a paper towel soaks up water, making the battery spill-proof even if the case is punctured. This also means a battery with AGM separators can be shipped by normal means (no spillage) and installed in any position. AGM separators provide extra cushioning and are more resist to vibration damage (a leading cause of battery failure).
Some premium batteries also use a new type of "spiral-wound" cell construction instead of flat plates. This allows a greater surface area for higher power density. The six battery cells are arranged like beverage cans in a six-pack. The result is a very compact, efficient design that delivers more cranking amps during the initial three to five seconds of cranking. The spiral-wound cells also produce a slightly higher voltage that raises the battery's overall voltage output by 15 percent for added cranking power. The tightly wound spiral cells typically hold a charge longer than flat plate cells, which means the battery can sit for months without being used and still crank an engine. The spiral-wound construction also offers improved durability making this type of battery ideal for rugged-use applications.
New high-voltage batteries (up to 274 volts) are also being used in hybrid vehicles. In the first-generation Toyota Prius, a stack of 38 7.2 volt Nickel Metal Hydride (NHM) batteries are combined in series to produce the power needed to run the car’s electric motor and operate the engine stop-start system. The second generation Prius uses a smaller 28 NHM battery pack with a voltage rating of only 201 volts, but it’s amperage output is actually higher than the previous battery. These are very expensive batteries and are covered by an extended warranty. Hybrid replacement batteries are not yet available in the aftermarket - but that will eventually change as more and more hybrid vehicles go into production. Both Ford and GM have hybrids coming (though in limited numbers), and Toyota and Honda are ramping up their production.

Lithium-Ion Car Battery
For automotive applications, Valence Technology, Inc. has introduced a new lithium-ion car battery. The "U-Charge" system's patented "Saphion" Lithium-ion technology offers twice the amp capacity of an ordinary battery of the same size, and one third of the weight. It also charges faster and lasts up to four times longer than a lead-acid battery says the company. The battery can be used as a direct replacement for an ordinary car battery. Saphion technology utilizes a phosphate-based cathode material in place of metal-oxide materials that are typically used in Lithium-ion batteries. Saphion technology is chemically and thermally stable, making it safer than lead-acid batteries.