Lithium-ion Battery
A lithium-ion battery, also known as the Li-ion battery, is a type of secondary (rechargeable) battery composed of cells in which lithium ions move from the anode through an electrolyte to the cathode during discharge and back when charging.
The cathode is made of a composite material (an intercalated lithium compound) and defines the name of the Li-ion battery cell. The anode is usually made out of porous lithiated graphite. The electrolyte can be liquid, polymer, or solid. The separator is porous to enable the transport of lithium ions and prevents the cell from short-circuiting and thermal runaway.
Chemistry, performance, cost, and safety characteristics vary across types of lithium-ion batteries. Handheld electronics mostly use lithium polymer batteries (with a polymer gel as electrolyte), a lithium cobalt oxide (LiCoO2) cathode material, and a graphite anode, which offer high energy density.
Li-ion batteries, in general, have a high energy density, no memory effect, and low self-discharge. One of the most common types of cells is 18650 battery, which is used in many laptop computer batteries, cordless power tools, certain electric cars, electric kick scooters, most e-bikes, portable power banks, and LED flashlights. The nominal voltage is 3.7 V.
Note that non-rechargeable primary lithium batteries (like lithium button cells CR2032 3V) must be distinguished from secondary lithium-ion or lithium-polymer, which are rechargeable batteries. Primary lithium batteries contain metallic lithium, which lithium-ion batteries do not.
Advantages and Disadvantages of Lithium-ion Batteries
There are many advantages to using a Li-ion cell. As a result, the technology is being used increasingly for a huge number of widely varying applications. A lithium-ion battery offers advantages over other battery types in several areas.
Advantages:
The main advantage of rechargeable cells is that they may be recharged after discharge. Therefore, rechargeable batteries are more environmentally friendly than primary batteries. Not only can they be used repeatedly, but they generate less waste over the long term. This is particularly true in the case of power-intensive devices, which consume batteries at an increased rate. Another very important advantage is a high C-rate. Rechargeable cells have better power output capabilities compared to primary cells and are used for high-power applications.
There are several specific advantages to lithium-ion batteries.
- Cell voltage. Lithium-ion batteries have a high operating voltage of 3-5 volts, depending on the specific chemistry. This allows for an equivalent power operation at a lower current draw, and the battery will last longer on a single charge.
- High energy density. Lithium-ion batteries have a high energy density, so lithium-ion batteries are lightweight and compact. NCA’s usable charge storage capacity is about 180 to 200 mAh/g. The capacity of NCA is significantly higher than that of alternative materials such as LiCoO2 with 148 mAh/g, LiFePO4 with 165 mAh/g, and NMC 333 (LiNi0,33Mn0,33Co0,33O2)with 170 mAh/g.
- No memory effect. Unlike NiCd and older NiMH batteries, Li-ion batteries do not exhibit any memory effect and have long shelf lives – up to 5 years. Ni-Cd cells required a periodic discharge to ensure that they did not exhibit the memory effect.
- Low self-discharge. Li-ion rechargeable batteries have a self-discharge rate typically stated by manufacturers to be 1.5–2% per month. Old rechargeable batteries self-discharge more rapidly, especially nickel-based batteries. A freshly charged nickel-cadmium (Ni-Cd) battery loses 10% of its charge in the first 24 hours and thereafter discharges at a rate of about 10% a month.
- Load characteristics. The load characteristics of a lithium-ion cell or battery are reasonably good. They provide a reasonably constant 3.6 volts per cell before falling off as the last charge is used.
Disadvantages:
Battery price is one of the challenging factors in choosing the right rechargeable battery for your device or applications. It greatly affects the decision of the buyer. Rechargeable batteries have higher initial costs than their primary counterparts. Another important disadvantage is their self-discharge. In low-drain applications, the service life is more important, and the self-discharge characteristics of a rechargeable battery mean that they are less suitable for use as the primary energy source.
There are several specific disadvantages to lithium-ion batteries.
- An electronic battery management system is required. Lithium-ion batteries use monitoring electronics to ensure over-charge and deep-discharge protection.
- A thermal management system is required. Batteries generate heat when being charged or discharged, especially at high currents. Large battery packs, such as those used in electric vehicles, are generally equipped with thermal management systems that maintain a temperature between 15 °C (59 °F) and 35 °C.
- Ageing. One of the major lithium-ion battery disadvantages for consumer electronics is that lithium-ion batteries suffer from ageing. Not only is this time or calendar dependent, but it is also dependent upon the number of charge-discharge cycles that the battery has undergone. Most modern 18650 lithium-ion batteries, which are common for laptop batteries, have a typical cycle life of 300 – 500 (charge, discharge cycles). When in C-rate or high DOD situations, this can decrease substantially to 200 cycles.
- Higher cost. A major lithium-ion battery disadvantage is its cost. Typically they are around 40% more costly to manufacture than NiMH cells.
