A rapid series of technological breakthroughs in battery design have made it possible to mass-produce electric cars and vans by 1985, according to industry officials.

General Motors Corp. is planning production of electric vehicles in 1985, perhaps a year sooner, according to its chairman, Thomas A. Murphy. "We're going to pursue it as aggressively as we can," he said in an interview. "

Although the company has not described in detail the vehicles it will build, industry sources believe GM is working on a small, two-seat runabout designed as a second car for urban use.

An advanced battery system developed by Gulf & Western Industries Inc. appears capable of powering a four-door compact electric car at least 100 miles between recharging and may last 5 to 10 times longer than the lead-acid batteries currently used in electric vehicles, according to the Energy Department.

"All batteries have a problem of longevity. This one has the potential for much longer life. It might even last the life of the car," more than five years, said Paul J. Brown, director of the Electric and Hybrid Vehicle Division of the Energy Department.

Gulf & Western is expected to announce its battery soon as a major breakthrough in the development of electric cars.

The battery system, designed initially for use by electric utilities, is now being tested in vehicles, and the results, although incomplete, are very promising, Brown said. "I don't want to say we have solved all the problems," he said. "But we're much encouraged."

A durable battery-power system has been a critical missing link in electric vehicle planning and the main target of government and industry research since 1975 when Congress identified electric vehicles as a potential answer to the nation's energy problems.

GM, relying on its own, newly designed battery system, believe it can produce a car whose price and performance will appeal to a substantial number of buyers.

The Gulf & Western battery appears to be a major advance even on the GM design, according to Brown and industry sources.

With these developments and others, the future of the electric vehicle now depends more on consumer taste than technology, industry experts say.

The range and speed of electric cars, and thus their appeal, are related directly to battery technology.

The first generation of electric vehicle test cars was powered by modified lead-acid batteries similar to those in conventional gasoline-powered cars. Because of the battery weight, the cars typically travel only 45 miles in stop-and-go traffic before needing a recharge. Moreover, the entire battery system has to be replaced every one to three years at a cost of $300 or more.

Although millions of American motorists drive less than 45 miles a day, and thus could use a car with that range for shopping and commuting, there was no assurance they would buy such a car given the chance, and no automaker was ready to mass-produce one.

GM has said a range of at least 100 miles or more was essential to justify mass production.

Within a year, that gap has been closed.

Last summer, an experimental car built with $6 million in Energy Department funding was rolled out by General Electric Co., Chrysler Corp. dand Globe Union Inc.

Its range is estimated at 75 miles thanks to an improved lead-acid battery design, coupled with a braking system that helps recharge the batteries as the car slows. The car, a compact, four-passenger sedan, has a top speed of 60 miles an hour.

Last September, GM announced its "long-elusive breakthrough on a promising new battery" installed in a subcompact Chevette. GM's nickel-zinc oxide battery produces more than twice the power per pound of a lead-acid battery, GM said.

It has a top speed of 50 mpg, a range of 100 miles between recharging and a battery life of 30,000 miles.

"We still have a tremendous amount of development to do," GM President E. M. Estes said then. "But we've cleared a major technological obstacle to our plans to begin offering electric-powered vehicles in the mid-1980s."

How far GM has come isn't known outside the company because it hasn't shared its battery test results with the Energy Department.

Murphy said in an interview that the company believes there is a market for a small electric car, particularly among women who would rather have a car that can be recharged at home by plugging into a garage electric outlet than a gasoline-powered auto that must be refueled at service stations.

Indsutry sources expect that the GM electric car will be very small, perhaps the size of a Fiat two-seater popular in Italy as a second car. It probably will be expensive at first, aimed at upper-middle-income drivers, with less expensive versions being offered in later years, assuming a growing demand, according to Ernest T. Kendall, president of Commonwealth Reserach Group Inc., a Cambridge, Mass., research firm.

Road tests of the Gulf & Western battery system are expected to demonstrate a range of at least 100 miles between recharging, said Brown.

In conventional lead-acid batteries, the potential power is locked inside in the metal plates or poles that produce ions in contact with an acid solution. In the process, the metal gradually is consumed, however, and because the plates inside the battery cannot be replaced, the entire battery eventually must be discarded.

The new Gulf & Western battery uses a cooled, liquid slurry to generate the current, despoition zinc ions on a comb-like graphite plate, said Brown. As the battery ages, more zinc slurry can be added without having to replace the batteries.

The system was designed in cooperation with the Electric Power Research Institute for use by utilities to store energy and has proven itself in that role. Brown said.

The critical remaining question is whether electric vehicles will be cheaper to operate in 1985 than gasoline-driven cars. Kendall says he has doubts -- the answer depends on the unpredictable future prices of gasoline and electric power.

Department of Energy research indicates electric cars will cost about 20 percent more than comparable gasoline-powered cars, but electric vehicle owners will make that up and more in lower operating costs, Brown said.