Various methods exist for recharging the batteries of electric cars. Currently, the largest concern surrounding electric vehicle transportation is the total travel range available before the need to recharge. The longest range recorded to date was 606.2 miles, achieved by a Tesla Model 3. However, this was conducted in very controlled conditions where the car maintained a constant speed without the added drain of the air conditioning compressor. [1] Typically, the battery would last for approximately 300 miles - the equivalent to three days of city commuting in warmer weather, or one day in colder weather. With these limitations, long-distance trips are currently unsuited for an electric car unless rapid charging stations are available on the route of the trip.
The process of discharging involves lithium ions from a positive electrode passing through a separator/electrolyte. The ions then transfer, via a solid electrolyte interface (SEI) and intercalate, into the negative electrode. The potential negative impact for rapid charging is that battery aging may be accelerated by the unstable SEI, produced by charging and discharging multiple times.
New pulse charging has significantly improved the stability of SEI since the unnecessary chemical reaction has been reduced by new charging methods and SEI is grown via a reduction reaction. Thus, a battery's life cycle and efficiency has also improved in comparison to the traditional charging method. [2] Also, in traditional charging method, ethylene might be produced during charging due to electrolyte (EC, mostly) reduction with lithium ions. Since the battery is closed, the internal pressure is contained. The produced ethylene will lead to overpressure inside the battery. Overpressure of the battery may also cause the battery to expand due to an internal temperature rise, potentially causing the battery to explode. By using these new composite waveform charging method, however, it can reduce the produced ethylene by suppressing the electrolyte reduction reaction. Therefore, giving a moderate energy for lithium ions to transfer during charging and a quick negative pulse to reduce unwanted chemical reactions, it seems to be a theoretical charging method in the future. [3]
The different algorithms vary in charging efficiency, charging time, battery life cycles, and costs. However, researchers still cannot define which is the most appropriate one for the application, as many algorithms have been developed; each one has advantages and disadvantages. For instance, the constant current-constant voltage charging method has a longer charging time compared to the multistage current charging algorithm, while the cost of research on the latter is higher than the former. Considering the pros and cons of each algorithm, the goal is to match each one with its appropriate application.
The constant current charging method adjusts the output voltage of charging devices or the resistance in series with the battery to keep the current constant. It uses a constant current value form the beginning to the end of charging. As nickel-cadmium batteries are easy to polarize during conventional charging, the electrolyte continuously produces hydrogen-oxygen gas in both conventional constant voltage and constant current charging algorithms. Under the action of internal high pressure, the oxygen penetrates to the negative electrode and interacts with the cadmium plate to generate CdO, resulting in the decrease of effective capacity of the electrode plate. As the acceptable current capacity of the battery decreases gradually with the progress of the charging process, this led to the overcharging of the battery in the later charging period. Eventually, it will also lead to a sharp drop in battery capacity. [4]
Constant voltage charging is a widely used charging method involving constant voltage between the battery poles. The starter battery uses constant voltage charging when the vehicle is running. If the specified voltage constant value is appropriate, it can ensure that the battery is fully charged, while also minimizing gas and water loss.
The boost charger CC/CV charging algorithm is a further development of the constant current/constant voltage algorithms. Instead of using the constant voltage and current in the entire charging period, it boosts the charging efficiency through maximizing voltage in the first period, with the battery reaching approximately 30% of its nominal charging capacity. After this period, the charging algorithm is then switched to the standard CC/CV. [5] Due to the initial higher charging voltage, the BC-CC/CV can charge the battery faster than the CC/CV, but it is required to fully discharge the battery before charging. As the charger needs to provide variable voltage, all components need to accept the highest voltage generated by the boost charger. Discharging the battery before recharging is important as this will influence the efficiency charging algorithm and the life cycle of batteries.
Multistage current charging divides the entire charging period into several charging stages that attempt to use the optimal charging current across each stage, maximize the charging efficiency. By determining the optimal charging current for each stage, the fuzzy controller is used to determine the charging current by the change in temperature. To sum up, this algorithm is based on a micro-controller or a computer. [6] The charging speed is faster and charging efficiency is higher than those of the CC/CV.
Non-contact charging utilizes magnetic resonance to transfer energy in the air between the charger and battery. This achieves a highly efficient energy transformation. [7] As the non-contact charger could keeping charging the vehicle, it allows EVs to have a smaller battery. By itself, it is more economical, safer and more sustainably developed. Since the battery is the major contributor to the cost of an EV, the MSRP of an EV is lowered as a result of the use of non-contact charging. However, developing a non-contact charging system involves huge financial support. For example, to realize real-time charging on the road, it requires installation of receiver coil under the car and reconstruct the road and put transmitter coil under the power supply track. In this way, it allows car to be automatically charged while operating on the road. [8] Due to this, many EV manufacturers are using traditional charging methods to keep costs low. Since non-contact charging systems rely on the electromagnetic field as their mechanism of action, electronic devices in close proximity to the charger may be negatively affected during charging. There is also the possibility that animals may be influenced. Efficiency is another concern for researchers.
Battery swapping involves the use of an automatic or semi-automatic system to exchange a depleted battery with a fully charged one. [9] This process can only be completed by technical personnel. The process is meant to achieve a comparable refueling time to a traditional gasoline vehicle, with swaps typically completed in roughly 3 minutes. In China, company like NIO have built more than 1151 battery swap stations to help popularize this technology. [10]
An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit. Electrodes are essential parts of batteries that can consist of a variety of materials (chemicals) depending on the type of battery.
An electrochemical cell is a device that generates electrical energy from chemical reactions. Electrical energy can also be applied to these cells to cause chemical reactions to occur. Electrochemical cells that generate an electric current are called voltaic or galvanic cells and those that generate chemical reactions, via electrolysis for example, are called electrolytic cells.
A nickel–metal hydride battery is a type of rechargeable battery. The chemical reaction at the positive electrode is similar to that of the nickel–cadmium cell (NiCd), with both using nickel oxide hydroxide (NiOOH). However, the negative electrodes use a hydrogen-absorbing alloy instead of cadmium. NiMH batteries can have two to three times the capacity of NiCd batteries of the same size, with significantly higher energy density, although only about half that of lithium-ion batteries.
The nickel–cadmium battery is a type of rechargeable battery using nickel oxide hydroxide and metallic cadmium as electrodes. The abbreviation Ni–Cd is derived from the chemical symbols of nickel (Ni) and cadmium (Cd): the abbreviation NiCad is a registered trademark of SAFT Corporation, although this brand name is commonly used to describe all Ni–Cd batteries.
A lithium-ion or Li-ion battery is a type of rechargeable battery that uses the reversible intercalation of Li+ ions into electronically conducting solids to store energy. In comparison with other commercial rechargeable batteries, Li-ion batteries are characterized by higher specific energy, higher energy density, higher energy efficiency, a longer cycle life, and a longer calendar life. Also noteworthy is a dramatic improvement in lithium-ion battery properties after their market introduction in 1991: over the following 30 years, their volumetric energy density increased threefold while their cost dropped tenfold.
A rechargeable battery, storage battery, or secondary cell, is a type of electrical battery which can be charged, discharged into a load, and recharged many times, as opposed to a disposable or primary battery, which is supplied fully charged and discarded after use. It is composed of one or more electrochemical cells. The term "accumulator" is used as it accumulates and stores energy through a reversible electrochemical reaction. Rechargeable batteries are produced in many different shapes and sizes, ranging from button cells to megawatt systems connected to stabilize an electrical distribution network. Several different combinations of electrode materials and electrolytes are used, including lead–acid, zinc–air, nickel–cadmium (NiCd), nickel–metal hydride (NiMH), lithium-ion (Li-ion), lithium iron phosphate (LiFePO4), and lithium-ion polymer.
A lithium polymer battery, or more correctly, lithium-ion polymer battery, is a rechargeable battery of lithium-ion technology using a polymer electrolyte instead of a liquid electrolyte. Highly conductive semisolid (gel) polymers form this electrolyte. These batteries provide higher specific energy than other lithium battery types. They are used in applications where weight is critical, such as mobile devices, radio-controlled aircraft, and some electric vehicles.
An automotive battery, or car battery, is a rechargeable battery that is used to start a motor vehicle.
The AA battery is a standard size single cell cylindrical dry battery. The IEC 60086 system calls the size R6, and ANSI C18 calls it 15. It is named UM-3 by JIS of Japan. Historically, it is known as D14, U12 – later U7, or HP7 in official documentation in the United Kingdom, or a pen cell.
A battery charger, recharger, or simply charger, is a device that stores energy in an electric battery by running current through it. The charging protocol—how much voltage, current, for how long and what to do when charging is complete—depends on the size and type of the battery being charged. Some battery types have high tolerance for overcharging after the battery has been fully charged and can be recharged by connection to a constant voltage source or a constant current source, depending on battery type.
State of charge (SoC) quantifies the remaining capacity available in a battery at a given time and in relation to a given state of ageing. It is usually expressed as percentage. An alternative form of the same measure is the depth of discharge (DoD), calculated as 1 − SoC. It refers to the amount of charge that may be used up if the cell is fully discharged. State of charge is normally used when discussing the current state of a battery in use, while depth of discharge is most often used to discuss a constant variation of state of charge during repeated cycles.
A lithium-ion capacitor is a hybrid type of capacitor classified as a type of supercapacitor. It is called a hybrid because the anode is the same as those used in lithium-ion batteries and the cathode is the same as those used in supercapacitors. Activated carbon is typically used as the cathode. The anode of the LIC consists of carbon material which is often pre-doped with lithium ions. This pre-doping process lowers the potential of the anode and allows a relatively high output voltage compared to other supercapacitors.
Rechargeable lithium metal batteries are secondary lithium metal batteries. They have metallic lithium as a negative electrode. The high specific capacity of lithium metal, very low redox potential and low density make it the ideal negative material for high energy density battery technologies. Rechargeable lithium metal batteries can have a long run time due to the high charge density of lithium. Several companies and many academic research groups are currently researching and developing rechargeable lithium metal batteries as they are considered a leading pathway for development beyond lithium-ion batteries. Some rechargeable lithium metal batteries employ a liquid electrolyte and some employ a solid-state electrolyte.
An electric battery is a source of electric power consisting of one or more electrochemical cells with external connections for powering electrical devices. When a battery is supplying power, its positive terminal is the cathode and its negative terminal is the anode. The terminal marked negative is the source of electrons that will flow through an external electric circuit to the positive terminal. When a battery is connected to an external electric load, a redox reaction converts high-energy reactants to lower-energy products, and the free-energy difference is delivered to the external circuit as electrical energy. Historically the term "battery" specifically referred to a device composed of multiple cells; however, the usage has evolved to include devices composed of a single cell.
The lithium–air battery (Li–air) is a metal–air electrochemical cell or battery chemistry that uses oxidation of lithium at the anode and reduction of oxygen at the cathode to induce a current flow.
A supercapacitor (SC), also called an ultracapacitor, is a high-capacity capacitor, with a capacitance value much higher than solid-state capacitors but with lower voltage limits. It bridges the gap between electrolytic capacitors and rechargeable batteries. It typically stores 10 to 100 times more energy per unit volume or mass than electrolytic capacitors, can accept and deliver charge much faster than batteries, and tolerates many more charge and discharge cycles than rechargeable batteries.
Research in lithium-ion batteries has produced many proposed refinements of lithium-ion batteries. Areas of research interest have focused on improving energy density, safety, rate capability, cycle durability, flexibility, and reducing cost.
A dual carbon battery is a type of battery that uses graphite as both its cathode and anode material. Compared to lithium-ion batteries, dual-ion batteries (DIBs) require less energy and emit less CO2 during production, have a reduced reliance on critical materials such as Ni or Co, and are more easily recyclable.
Lithium–silicon batteries are lithium-ion battery that employ a silicon-based anode and lithium ions as the charge carriers. Silicon based materials generally have a much larger specific capacity, for example 3600 mAh/g for pristine silicon, relative to the standard anode material graphite, which is limited to a maximum theoretical capacity of 372 mAh/g for the fully lithiated state LiC6.
An aqueous lithium-ion battery is a lithium-ion battery (Li-ion) that uses a concentrated saline solution as an electrolyte to facilitate the transfer of lithium ions between electrodes and induce an electrical current. In contrast to non-aqueous lithium-ion batteries, aqueous Li-ion batteries are nonflammable and do not pose any significant risks of explosion, because of the water-based nature of their electrolyte. They also lack the poisonous chemicals and environmental risks associated with their non-aqueous counterparts.
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