What are the three characteristics and performance of rechargeable batteries?

What are the three characteristics and performance of rechargeable batteries?

In order to eliminate dependence on expensive petroleum and reduce the adverse health effects of harmful gases, energy experts are eager to explore backup battery technologies that may be used in electric vehicles (EV) and hybrid electric vehicles (HEV). Energy experts and transportation consultants recommend the use of high-capacity lithium-ion rechargeable batteries for electric vehicles and hybrid vehicles. The battery designer pointed out that Nissan Motor Co. and Sony Corporation have deployed rechargeable lithium battery packs in their electric and hybrid vehicles. General Motors and Siemens have invested heavily in research and development of fuel cells that are most suitable for trucks and buses. Zero emission vehicle (ZEV) battery requirements will be more stringent. Sealed nickel-cadmium batteries (Ni-Cd) are currently used in commercial (MD-80, DC-9, Boeing 777) and military aircraft (F-16, F-18, E-8). In order to meet the requirements of long life and reliability, the exhausted nickel-cadmium batteries used in various commercial and military aircrafts should be replaced with high-performance, maintenance-free sealed nickel-cadmium rechargeable batteries. Sealed lead-acid (Pb-acid) and vented nickel-cadmium rechargeable batteries are widely used in commercial and military aircraft to meet the requirements of improving efficiency, reliability, life and output power.

The demand for new generation batteries will focus on low cost, light weight, compact packaging, portability, and a service life of more than 15 years. Rechargeable batteries will be very suitable for many applications such as battlefield weapons, communication satellites, space reconnaissance and surveillance systems, underwater tracking sensors, etc. Note that large-capacity batteries are particularly suitable for commercial and military aircraft, helicopters, drones, hybrid vehicles, space sensors and battlefield weapons, while low-power rechargeable batteries are widely used in mobile phones, laptops, medical equipment, computers, and Many other electronic and digital devices. In the design and development of next-generation rechargeable batteries, the integration of miniaturization technologies including microelectromechanical systems (MEMS) and nanotechnology will be carefully considered to meet stringent performance specifications, including reliability, portability, longevity, and compression packaging.

In order to improve the design of nickel-zinc (Ni-Zn) rechargeable batteries, active research and development activities are currently being carried out. One of the key requirements is to provide the lowest transportation cost (0.03~0.44) USD/km. Design and development activities must focus on key electrical parameters, such as state of charge (SOC), thermal breakdown, charge and discharge rates, discharge cut-off detection, and the correlation between state of charge and open circuit voltage (OCV). For battlefield rechargeable batteries, weight, size, cost, reliability, and life are the most important design requirements.

Regardless of its application field, secondary or rechargeable batteries have the following three distinct characteristics:
·Energy performance;
·Power performance;
·Life (actual time and charge-discharge cycle).

These characteristics are inextricably linked. In other words, to increase one item, the other or two must be reduced. For example, increasing the size of the current collector in the battery to increase the mass energy density will reduce the space for the active electrode material, which will reduce the volume energy density. Both mass energy density and volumetric energy density are essential for rechargeable batteries installed in electric and hybrid electric vehicles. Currently, there is no electric car that can drive without refueling. In order to solve this important problem, the latest technology is indispensable in the design and development of rechargeable batteries for electric vehicles and hybrid electric vehicles.

Regardless of its application area, the following terms are used to define battery performance:
·Anolyte: liquid anode.
· Catholyte: liquid cathode.
·DOD: Depth of discharge.
·Electrolyte: The medium through which ion migration promotes the flow of electrons.
·Volume energy density: the electric energy stored per unit volume of the battery at a specific discharge rate. Also called volumetric energy, expressed as W·h/L.
·Volume power density: in a specific state of charge, usually 20%, the power that a unit volume of the battery can deliver. Also called volume ratio power, expressed as W/L.
·Mass Energy Density: In a specific state of charge, the electric energy per unit mass of the battery can be stored. Also called mass specific energy, expressed as W·h/kg.
·Specific power: In a specific state of charge, usually 20%, the power that can be delivered per unit mass of the battery. Also called mass power density, expressed as watts per kilogram (W/kg).
·SOC: This represents the percentage of the total ampere-hour capacity stored in the battery, called the state of charge.