Batteries can be categorized into two types based on their charging/discharging methods: one type can only discharge and cannot be recharged, while the other can both be charged and discharged. To enhance your understanding of batteries, this article will introduce battery performance parameters and paper batteries. If you are interested in batteries, please continue reading.
I. Battery Performance Parameters
1. Internal resistance
The internal resistance of a battery refers to the resistance encountered when current flows through the battery's interior. It includes ohmic internal resistance and polarization internal resistance, with polarization internal resistance further divided into electrochemical polarization internal resistance and concentration polarization internal resistance. Due to the existence of internal resistance, the battery's operating voltage is always less than its electromotive force or open-circuit voltage. The battery's internal resistance is not constant; it changes continuously (gradually increases) over time during charging and discharging because the composition of the active materials, the concentration of the electrolyte, and the temperature are constantly changing. Ohmic internal resistance obeys Ohm's law, while polarization internal resistance increases with increasing current density, but not linearly. It generally increases with increasing current density.
Internal resistance is an important indicator that determines battery performance. It directly affects the battery's operating voltage, operating current, output energy, and power. For batteries, the lower the internal resistance, the better.
2. Impedance
A battery has a large electrode-electrolyte interface area, so it can be considered equivalent to a series circuit of a large capacitor and a small resistor and inductor. However, the actual situation is much more complex, especially since the battery impedance changes with time and DC level, and the measured impedance is only valid for the specific measurement state.
II. Paper Batteries
(I) What is a paper battery?
Paper batteries are batteries that use paper as a carrier. They are made by coating paper with a special ink made of silver and carbon nanomaterials, offering a glimmer of hope for lightweight, high-efficiency new energy storage.
A paper battery is a type of battery made from sheet-like cellulose, named for its resemblance to both cellulose sheets and paper. It is manufactured by filling sheet-like cellulose with neatly arranged carbon nanotubes. These carbon nanotubes act as electrodes, conducting electricity. Its function is similar to both lithium-ion batteries and supercapacitors. Compared to conventional batteries, it provides a long-term, stable power output and, like a supercapacitor, can rapidly release high energy. While conventional batteries combine several individual components, paper batteries integrate all battery components into a single structure, making them more efficient.
(II) Advantages of Paper Batteries
1. Increasingly lightweight. It can be made 20 nanometers thick, which is about 5,000 times the diameter of a human hair.
2. High stability. It adopts solid "electrolyte", can be cut and cut freely without leakage, and will not explode under puncture, stretching and other conditions.
3. Low temperature resistance. Under the conditions of a low-temperature flamethrower at 1300 degrees Celsius, the paper battery will not catch fire or explode.
4. High adaptability. It can be bent and folded freely, and can be used normally between -70°C and 150°C.
5. Faster charging and longer lifespan. The energy density of paper batteries is approximately 90 watt-hours per kilogram, roughly half that of traditional batteries, comparable to the latest lithium-ion batteries, and twice the energy potential of lead-acid car batteries.
6. It does not contain any harmless chemicals or heavy metals.
(III) Market Prospects for Paper Batteries
This paper battery performs just as well as traditional batteries in terms of energy storage and charge cycle life. Experiments show that incorporating carbon nanotube paper into a traditional rechargeable battery can reduce weight by 20%. Pei-Dong Yang, a chemistry professor at the University of California, Berkeley, believes this technology could be commercialized in the near future.
Professor Sun Kening of the Department of Applied Chemistry, School of Science, Harbin Institute of Technology, believes that each type of battery is specifically designed and invented to meet different needs. Because different batteries have different characteristics, no single battery can be universally applicable, and this new type of paper battery is no exception.
As a novel battery concept, the new paper battery certainly has promising applications. However, judging from the published production method, the production cost of the carbon nanotubes required for this type of paper battery is very high, making it unsuitable for mass production. Therefore, its practicality is limited. This new paper battery can only be positioned as an exploratory research invention. Due to technological and other limitations, it cannot replace other widely used types of batteries, nor is it likely to capture the market in the short term.
This makes it an ideal power source for laptops, mobile phones, digital cameras, and even automobiles. Due to its high plasticity, this battery can even be shaped like a car door. It also offers unparalleled advantages over other batteries in powering miniature medical devices (such as pacemakers). Researchers are working to reduce the cost of paper batteries, hoping to one day mass-produce them using printing technology, much like printing newspapers.
