How do Lithium Batteries Work?

G.N.Lewis led efforts to pioneer lithium-ion batteries in 1912, but it was not until 1970 that the first non-rechargeable lithium-ion batteries became commercially available. In 1980, lagged, rechargeable lithium battery was researched and tried to develop but failed due to the instability of lithium metal as a cathode material.

Of all the metals, lithium is the lightest and has the most considerable electrochemical degree, providing the most significant specific energy per weight. Rechargeable batteries with lithium metal just on the anode can offer a high energy density, but around 1985 lithium ion batteries discovered that the anode could produce unwanted crystals due to cycling. At the same time, these particles can penetrate the diaphragm and cause an electrical short circuit. “Flame emission” refers to the battery after a short course, the temperature rises rapidly, close to the melting point of lithium, heat conduction out of control. In 1991, a lithium ion battery recalled a large shipment of rechargeable lithium-metal batteries shipped to Japan after a man’s face was burned by gas from a mobile phone battery.

Because lithium ions have their instability during charging, the research was transferred to non-metallic solutions using lithium ions. In 1991, the first lithium-ion battery was commercialized by SONY, and the chemical is now the fastest growing and sometimes most good storm on the market. Although the specific energy of lithium ion is lower than that of lithium metal, the main current display and voltage limits are observed, and lithium ion is safe.

Lithium ion battery developed by lithium cobalt oxide batteries because of John B. Goodenough (1922). After a successful collaboration between Goodenough and a graduate student in the United States hired by NTT, the student returned to Japan with the findings. In 1991, SONY announced that it had obtained a national patent for the Liguria oxide cathode. SONY won the patent after years of litigation. Goodenough and the other contributors received nothing in return, and the National Academy of Engineering honored Goodenough and the other contributors with the Les Stark Draper Award in 2014. And the following year, Israel awarded Goodenough a $1 million prize, which Goodenough donated to the Texas Institute for Materials Research.

The key to superior specific energy is a high battery voltage of 3.60V. Improved active materials and electrolytes can further enhance energy density. The stored energy is effectively utilized in a rational flat voltage spectrum with good load characteristics and a flat discharge curve of 3.70-2.80V /cell.

The 18650 cylindrical battery (1100 mah) cost more than $10 to make in 1994. But the price fell below $3 in 2001, when capacity rose to 1,900 mah. The 18650 battery has a high energy density that can deliver more than 3,000 mah of current, falling costs. Lithium-ion batteries are paving the way for widespread acceptance in portable applications, heavy industry, satellites, and power systems because of increased energy requirements, fewer toxins, and lower costs. The 18650 is 65mm in length and 18mm in caliber.

Lithium-ion batteries are a battery that does not require high maintenance, an advantage that most other chemical products lack. Batteries have no memory, so there is no need to exercise to stay in good shape. Lithium-ion batteries generally have less self-discharge than nickel-based systems, which helps fuel gauges. 3.60V is the voltage of the earring battery, which can directly power mobile phones, digital cameras, and tablets with a more straightforward design and lower cost compared to multiple batteries. The disadvantages are the need to protect the circuit from abuse and the high price.

Types of Lithium-ion Batteries

The conductor of lithium ions is an anode (positive electrode), a cathode (negative electrode), and an electrolyte. When a battery is discharged, the cathode is positive, and the anode is negative. The anode has many carbon holes, while the cathode is a metal oxide. During the discharge process, ions will flow from anode to cathode through electrolyte and separator, the charge will change direction, and ions will flow from cathode to anode.

Figure 1: Ion flow in lithium-ion battery.
When the cell charges and discharges, ions shuttle between the cathode (positive electrode) and anode (negative electrode). On discharge, the anode undergoes oxidation or loss of electrons, and the cathode sees a reduction or a gain of electrons. Charge reverses the movement.

There are many types of lithium-ion batteries, all of which have one thing in common: the slogan “lithium-ion.” Although similar at first glance, these cells all behave differently and are unique due to their choice of active materials.

The anode of the original SONY lithium-ion battery was coke. But since 1997, most lithium-ion manufacturers, including SONY, have used graphite for smoother discharge curves. Graphite is a form of carbon whose cyclic stability is a property used in pencils. This is the most common carbon, and there are also hard carbons and soft carbons. Nanotube carbons have yet to find commercial use in lithium ions due to their tendency to tangle and affect performance. But graphene could improve lithium ion performance in the future.

Figure 2 illustrates the voltage discharge curve of a modern Li-ion with graphite anode and the early coke version.

Figure 2: Voltage discharge curve of lithium-ion.
A battery should have a flat voltage curve in the usable discharge range. The modern graphite anode does this better than the early coke version. Courtesy of Cadex

Several additives, including silicon-based alloys, have been tried to improve the performance of graphite anodes. It requires a lithium ion bonded to six carbon (graphite) atoms; Four lithium ions bonded to one silicon atom. This means that silicon anodes could theoretically store ten times more energy than graphite, but at the same time, expansion of the anode during charging remains a problem. But pure silicon anodes are impractical. Only 3-5% of the silicon is added to the anode of the silicon base to achieve good cycle life.

When nano-structured lithium titanate is used as an anode additive, it has good cycle life, safety, load performance, and low temperature performance. But it’s lower energy and higher cost.

Cathodic and anodic materials can be tested to enhance the intrinsic quality, but in this way, the enhancement may damage the other. The so-called “power cell” optimizes the specific energy (capacity) for market line operation over long periods but has a lower specific power. Although the “power cell” provides extraordinary power, the accommodation is still lacking. Meanwhile, “hybrid cells” serve as a compromise that offers a bit of both.

Instead of expensive cobalt, manufacturers can add nickel, which is relatively easy to achieve with low cost and high specific energy, making the battery less stable. To gain quick market acceptance, startups may focus on low prices and high specific power, but at the same time, safety and durability still cannot be compromised. Reputable manufacturers highly value safety and service life. Table 3 summarizes the limitations and advantages of lithium ions.

This similar design is found in most lithium-ion batteries, consisting of a carbon/graphite negative electrode (anode) coated on a copper collector, an electrolyte made from lithium salts and a separator in an organic solvent, and a metal oxide positive electrode (cathode) overlaid on an aluminum collector.