Supercapacitor in the context of "Electric locomotive"

Ionic conductivity (denoted by λ) is the movement of ions through a solid material, a phenomenon central to solid-state ionics. It is denoted by λ and measured in siemens per meter (S/m). While perfect crystals of inorganic compounds are typically electrical insulators, ionic conduction arises when defects are introduced—either intrinsically through thermal activation or extrinsically via doping with aliovalent impurities. These defects enable ion migration by providing pathways through the crystal lattice. Solid ionic conductors, known as solid electrolytes, are critical components in technologies such as all-solid-state batteries, supercapacitors, fuel cells, and thin-film microelectronic devices. The ionic conductivity (σ) follows an Arrhenius-type relationship with temperature, governed by activation energy barriers influenced by crystal structure and defect chemistry. Ionic conduction is one mechanism of current.

Hybrid vehicle drivetrains transmit power to the driving wheels for hybrid vehicles. A hybrid vehicle has multiple forms of motive power, and can come in many configurations. For example, a hybrid may receive its energy by burning gasoline, but switch between an electric motor and a combustion engine.

A typical powertrain includes all of the components used to transform stored potential energy. Powertrains may either use chemical, solar, nuclear or kinetic energy for propulsion. The oldest example is the steam locomotive. Modern examples include electric bicycles and hybrid electric vehicles, which generally combine a battery (or supercapacitor) supplemented by an internal combustion engine (ICE) that can either recharge the batteries or power the vehicle. Other hybrid powertrains can use flywheels to store energy.

A hybrid electric vehicle (HEV) is a type of hybrid vehicle that couples a conventional internal combustion engine (ICE) with one or more electric engines into a combined propulsion system. The presence of the electric powertrain, which has inherently better energy conversion efficiency, is intended to achieve either better fuel economy or better acceleration performance than a conventional vehicle. There is a variety of HEV types and the degree to which each functions as an electric vehicle (EV) also varies. The most common form of HEV is hybrid electric passenger cars, although hybrid electric trucks (pickups, tow trucks and tractors), buses, motorboats, and aircraft also exist.

Modern HEVs use energy recovery technologies such as motor–generator units and regenerative braking to recycle the vehicle's kinetic energy to electric energy via an alternator, which is stored in a battery pack or a supercapacitor. Some varieties of HEV use an internal combustion engine to directly drive an electrical generator, which either recharges the vehicle's batteries or directly powers the electric traction motors; this combination is known as a range extender. Many HEVs reduce idle emissions by temporarily shutting down the combustion engine at idle (such as when waiting at the traffic light) and restarting it when needed; this is known as a start-stop system. A hybrid-electric system produces less tailpipe emissions than a comparably sized petrol engine vehicle since the hybrid's petrol engine usually has smaller displacement and thus lower fuel consumption than that of a conventional petrol-powered vehicle. If the engine is not used to drive the car directly, it can be geared to run at maximum efficiency, further improving fuel economy.

A fuel cell vehicle (FCV) or fuel cell electric vehicle (FCEV) is an electric vehicle that uses a fuel cell, sometimes in combination with a small battery or supercapacitor, to power its onboard electric motor. Fuel cells in vehicles generate electricity generally using oxygen from the air and compressed hydrogen. Most fuel cell vehicles are classified as zero-emissions vehicles. As compared with internal combustion vehicles, hydrogen vehicles centralize pollutants at the site of the hydrogen production, where hydrogen is typically derived from reformed natural gas. Transporting and storing hydrogen may also create pollutants. Fuel cells have been used in various kinds of vehicles including forklifts, especially in indoor applications where their clean emissions are important to air quality, and in space applications. Fuel cells are being developed and tested in trucks, buses, boats, ships, motorcycles and bicycles, among other kinds of vehicles.

The first road vehicle powered by a fuel cell was the Chevrolet Electrovan, introduced by General Motors in 1966. The Toyota FCHV and Honda FCX, which began leasing on December 2, 2002, became the world's first government-certified commercial fuel cell vehicles, and the Honda FCX Clarity, which began leasing in 2008, was the world's first fuel cell vehicle designed for mass production rather than adapting an existing model. In 2013, Hyundai Motors began production of the Hyundai ix35 FCEV, claimed to be the world's first mass-produced fuel cell electric vehicle, which was subsequently introduced to the market as a lease-only vehicle. In 2014, Toyota began selling the Toyota Mirai, the world's first dedicated fuel cell vehicle.