Currently, most new energy vehicles on the market primarily charge from fixed charging stations. However, the number of fixed charging stations is far fewer than gas stations, and the charging time is longer, which undoubtedly restricts the development of new energy vehicles. Although China has made great efforts in the construction of charging infrastructure, when new energy vehicles are traveling on the road or in remote areas, they often lack available charging facilities in case of an emergency power cut, leading to concerns about long-distance travel in electric vehicles. Having a convenient and portable on-board charging device to extend the vehicle's operating time has always been a focal point of interest. In recent years, portable car charging power banks have provided another solution to address the range issues of new energy vehicles.

A portable car charging power bank is an integrated battery device that combines energy storage, voltage boosting, and charging/discharging functions. It stores external power input in the form of chemical energy and converts it back to electrical energy when needed for charging, which is the well-known charging and discharging process. Taking lithium-ion batteries as an example, their main components include the cathode, separator, anode, and organic electrolyte. The cathode is made of materials such as lithium manganese oxide or lithium cobalt oxide. The separator is a high molecular film that allows lithium ions to pass through freely but blocks electrons. The anode primarily consists of graphite and carbon materials similar to graphite. The organic electrolyte is a carbonate solvent dissolved with lithium hexafluorophosphate.

The reaction of a lithium-ion battery can be seen as lithium ions being released from the cathode and entering the graphite, while during discharge, lithium ions are released from the graphite anode and return to the cathode. Additionally, since charging is not possible under the same potential voltage, the power bank uses a voltage-boosting system to increase the discharge voltage to the required level for the vehicle, thus meeting the demand for multiple cycles of electricity use.

The challenge for researchers in designing a car charging power bank lies in adding a battery management system and an inverter. The battery management system is a real-time system that controls, protects, and monitors the safe operation of battery packs in electric vehicles, including functions such as temperature and voltage level monitoring. The inverter converts direct current (DC) into alternating current (AC) with fixed or adjustable frequency and voltage to ensure the normal operation of other electrical equipment in the car.

With the increasing popularity of new energy vehicles, both domestic and international research and development efforts on car charging power banks have been intensifying. In 2021, a British startup named ZipCharge launched a portable car charging power bank, which is about the size of a briefcase. It contains a lithium-ion battery weighing 22.7 kilograms, with a net capacity of 4 kilowatt-hours and a charging power of 7.2 kilowatts. It can extend the maximum range by 30 kilometers after half an hour of charging. Subsequently, China's Envision Technology Company introduced the world's first green charging robot, with a capacity of 70 kilowatt-hours and a charging power of 42 kilowatts. It can enable a new energy vehicle to travel 600 kilometers after two hours of charging. Another product from China's Tieqiu Energy Company is a new energy vehicle charging power bank, about the size of a printer, weighing around 22 kilograms, with a maximum power of 5 kilowatts. It can provide a range of 70 to 100 kilometers after two hours of charging.