Portable Lithium-Ion Battery
Portable lithium-ion battery are the most popular batteries in electronics like cellphones and laptops. They also power cordless tools, digital cameras and more.
Lithium-ion batteries contain critical minerals like cobalt, graphite and lithium. When they are disposed in the trash, we lose these resources. To avoid this, recycle your batteries.
High Energy Density
The energy density of a battery refers to the amount of power it can emit in relation to its size. The higher the Portable lithium-ion battery energy density, the smaller and lighter a battery can be. This makes them ideal for small and lightweight products like smartphones and tablets, where there isn’t much room for a large battery.
Most lithium batteries in portable devices today are cobalt-based. They feature a cobalt oxide positive electrode (cathode) and graphite carbon negative electrode (anode). Other types of lithium batteries have different cathodes including manganese, nickel-cobalt, and phosphate, but they all share the same core design. The most important factor separating them is their energy density, which determines how much run-time they can deliver and what applications they can be used in.
All rechargeable batteries will lose charge over time, but lithium ion batteries have a very low self-discharge rate. They only discharge 1.5% to 2% a month, which is significantly lower than other types of batteries.
Li-ion batteries are also able to tolerate fast charging, which is very important in some applications where users need their portable devices to be as powerful as possible. However, it is critical to properly manage these batteries during the fast-charge process in order to prevent safety issues, such as overheating or thermal runaway. Fast-charging requires precise control over the current flow, voltage and temperature to avoid damaging the battery.
Fast Charging
The high volumetric energy density of lithium batteries makes them ideal for powering portable devices. Their small size allows them to be packaged into spaces too tight for lead acid batteries. In addition, their thin anode allows for a large amount of surface area that enables fast charging.
The fast charging speed of Li-ion is a result of the fact that the negative electrode (anode) is composed of a carbon material with a high capacity per volume, and that Portable lithium-ion battery the positive electrode (cathode) is a metal oxide with low resistance to electron and ion transport. A battery management system controls the current flowing through the anode to prevent overcharging and overdischarging, as well as preventing the formation of the solid electrolyte interphase (SEI), which is detrimental to cycle life.
To ensure the safety of a lithium battery, it should be stored in a vented container and with a non-aqueous electrolyte such as ethylene or propylene carbonate. This is a vital step to reduce the risk of thermal runaway, which could cause an explosion.
Although lithium batteries are fairly maintenance free, a periodic “balancing” process is required to ensure that the individual cells in a battery pack have the same charge state. This is done automatically by the BMS during constant voltage (CC) charging. During the CC phase, the charger applies a continuous voltage equal to the maximum cell voltage times the number of cells in series until the current declines to 3% of the initial constant charge current.
Long Lifespan
Many consumer electronic devices like mobile phones, laptops and digital cameras are powered by lithium-ion batteries. They are also used in energy storage systems for sustainable energy sources and electric (hybrid) vehicles. A typical lifespan of a rechargeable lithium-ion battery is 2-3 years or 300-500 charge cycles, whichever happens first.
A rechargeable Li-ion battery ages by slowly losing its ability to hold a charge. This is referred to as capacity loss or power fading. It is caused by several processes that occur simultaneously and cannot be studied independently. Capacity loss is increased by elevated temperature, dwelling at a full state of charge, cycling and aging.
The longevity of a rechargeable lithium-ion Battery can be extended by carefully managing its usage. It is best to use the battery in a device that uses it as intended and confirm its status regularly by following its user handbook. It is also recommended to drain the battery to about 50 percent of its capacity and keep it at a moderately low temperature. The cycle life differs depending on the battery type, charge time and loading protocol and the operating temperature. Lab tests often report cycle counts that are not attainable in the field. The performance of a battery in its actual application is more important than the cycle count. The optimum operating condition is to keep the battery in mid-state of charge.
Safety
The high energy density of lithium-ion batteries makes them sensitive to local damage, leading to unwanted side reactions and thermal runaway. Those undesirable reactions can lead to battery fires, explosions, and even combustion of the whole vehicle. Consequently, safety regulations on LIBs are very strict.
The root causes of battery failures are various parasitic side reactions in the cathode, anode, and electrolyte of a cell (Fig. 2a-c). Unwanted heat and gas generation from these reactions are the major reasons for batteries’ thermal runaway. These reactions can be triggered during mechanical, electrical, and thermal abuses of a battery, such as broken separator or oxygen evolution on the cathode side.
During normal operation, the heat generated by anodic and cathodic reactions is dissipated quickly through external cooling and internal oxidation. The cooling rate of a battery is determined by its external surface area and geometry, and the cell’s structure and geometry. Currently, automakers are selecting pouch cells for their EV models, prismatic cells for BYD Tang and Song models, and cylindrical cells for SAIC Motor’s ROEWE R ER6 model. Regardless of the type of cell, it is important for manufacturers to design and engineer safe batteries through their internal strategies, such as improving cell chemistry, temperature management, and cooling rate. Besides, they also need to conduct rigorous tests and develop appropriate test standards for their batteries.
