By the 1990s, energy-dense nickel-metal hydride batteries were on the market, soon followed by lithium-ion batteries.

到了 20 世纪 90 年代，市场上出现了高能量密度的镍氢电池，很快，锂离子电池也问世了。

A lot of those battery life myths you might hear apply to nickel-cadmium and nickel-metal hydride batteries.

你听到的很多关于延长电池寿命的小窍门，仅适用于镍镉和镍氢电池。

Hybrids aren't true electric vehicles; their nickel-metal hydride batteries are only used to optimize the efficiency of gas-burning engines.

混合动力车并不是真正的电动汽车；他们的镍氢电池仅用于优化燃汽油发动机的效率。