Scientific intro of energy density of a battery
Energy density of a battery refers to the amount of charge a battery can hold relative to its weight, typically measured in Watt-hours per kilogram (Wh/kg).
Practically, the battery energy taken in watts of a battery fractionates by its weight in kgs. The resulting value in Wh/ kg is our required energy density With that being said, higher the energy density, the more charge-emitting capacity of a battery because of the more charges it holds, resulting in a long-lasting battery. This article provides the scientific introduction, key concepts and factors of energy density of a battery.
Table of Contents
What is energy density of a battery?
The energy density of lithium-ion battery proves to be the highest among all batteries. These batteries function on the mobility of ions from the cathode to the anode in lithium ion battery and vice versa. The mobility of ions inside the battery is responsible for creating a potential difference that acts as voltage and powers electric device.
Acknowledging the functioning, let us proceed to the energy density of lithium-ion battery. It comes in various sorts that are explained below
- Lithium-Nickel-Cobalt-manganese oxide is commonly used in electric vehicles and portable electronics due to its high energy density, ranging from 200-300 Wh/kg.
- Lithium-ferro phosphate is considered an economical option, having a lower voltage which makes it less energetic as compared to other lithium-ion batteries. The energy density ranges from 90-160 Wh/kg.
- Lithium Nickel-Cobalt-Aluminum Oxide contains high energy density and is preferred in electric cars for its capacity and reliability. Energy density ranges from 200-220 Wh/kg.
- Lithium Titanate Oxide is one of the fastest charging batteries with energy density ranging from 50-80 Wh/ kg. This low energy density, however, makes it less likely to be used in high-performance devices.
How to calculate energy density of a battery?
The energy density of a battery can be calculated using the variables battery voltage (V), battery capacity (Ah), and battery weight (Kg). In fact, when multiplying battery voltage (V) by battery capacity (Ah), you will get Wh. For the specific differences between these battery terms, you can read WH vs ah.The formula is as follows
Energy density = V x Ah / Kg
Take the energy density of lithium-ion battery as an example. Consider a 1kg lithium-ion battery having a 3V voltage with a capacity of 150 Ah. Putting variables in the formula
Energy density = 3 x 150 / 1 = 450 Wh kg-1
What is difference between energy density and power density?
Confusion occurs between these two terms as they closely relate to each other. Power density and energy density both relates to battery energy, however, the distinction occurs in the application of these terms in a battery.
The main difference is that energy density is the quantity of charge a battery possesses(Wh) per unit volume or weight while power density refers to the maximum power a battery can provide(W) per unit volume or weight. It signifies that power density means the rate at which the battery outputs while energy density refers to the amount of charge it stores. On the whole, we conclude that a battery with a high power density and high energy density is an ideal one, considering that it holds large charges and can provide strong energy.
What’s the advantage of high energy density?
Getting to opt between a small battery with a huge charge stored and a comparatively larger battery with a low charge stored, what could be the possible course of action anybody would choose? Certainly, choosing a battery of smaller size storing huge charges. Here comes the acknowledgment of owning a high-density battery.
High energy density portrays a high amount of charge stored within a battery. This signifies larger energy being provided by a relatively smaller size of the battery. This portrays the convenience of high energy density as it holds more energy within less weight. These batteries take the lead where a huge charge is required in a compact space. EVs and mobile phones are common examples, and the same principle is increasingly applied in modern smart furniture, where integrated power systems must deliver reliable energy without adding bulk or compromising design aesthetics.
As mentioned, it carries more charges, occupying less space. This trait makes it unique and compatible with compact electronic devices as well as huge machineries, making it one of the most feasible battery option for devices.
Mentioning compact electronic devices, high energy density makes it convenient to store huge charges in portable/ mini devices like headphones, and mobile phones. Imagine carrying a laptop weighing 10kgs? Not really feasible , but these high energy density batteries make it possible.
The same goes for heavy machinery like automobiles and aircraft. Engineers tend to design these as lightweight as possible for maximum output.This not only enhances the performance of the overall machinery by reducing weight but also enables them to experience higher battery capacity.
Comparison of the energy density of different batteries
The table below demonstrates the energy densities and other salient features of different batteries including lead-acid batteries, NiMH, NiCad, and several lithium-ion batteries.
| Specifications | Lead acid | NiCad | NiMH | LFP | NMC | NCA |
|---|---|---|---|---|---|---|
| Cathode material | Lead acid | Nickel-cadmium battery | Nickel–metal hydride | Lithium ferro phosphate | Lithium Nickel Manganese Cobalt Oxide | Lithium Nickel-Cobalt-Aluminum Oxide |
| Energy density | 30-50 | 45-80 | 60-120 | 150-200 | 200-300 | 200-250 |
| Life cycle | 200-300 | 1000 | 300-500 | 4000 | 2000 | 2000+ |
| Voltage | 2 | 1.2 | 1.2 | 3.2 | 3.6-3.7 | 3.6-4 |
| Maintenance | 3-6 months | 30-60 days | 60-90 days | None | None | None |
It is pretty evident that the lithium family serves to be the leading battery in energy densities as well as other features including voltage, maintenance, and life cycle. However comparing the voltages, lead acid has a considerable performance after lithium-ion. Also, analyzing the life cycle, we see NiCad having a relatively satisfactory performance after lithium-ion. These both still do not compete to the extent of lithium-ion as their overall capacity still lacks behind.
The high energy density of lithium-ion battery is the basis for their usage in most predominant machinery. With that being stated, Lithium-ion NCA (NCA 1865/ 2170) with an energy density of 200-250 Wh/ kg is currently being used in the tesla model S and X. The reason is its highenergy density with the longest durability.
NMC serves the same purpose as of NCA. The difference comes in M (manganese) and A (aluminum), and their percentages used in their respective cathodes. LFP having comparatively low capacity then NCA and NMC, still performs to be the best alternative for these lithium-ion batteries. Thusly, energy density of lithium-ion battery makes them unique.
Why do lithium-ion batteries have high energy density?
The energy density of lithium-ion battery proves to be the most iconic. It is functioning based on a cathode of cobalt-oxide with graphite carbon in the anode. This composition of the cobalt-oxide cathode in a lithium-ion results in a high energy density. Furthermore, the reason behind the energy density of lithium-ion battery being high is their compact size with respect to their charge storing capacity. This charge-to-size ratio of lithium-ion batteries makes them capable of holding a high energy density of up to 265 Wh/ kg.
Can high energy density make a battery last longer?
Yes, it does. The literal meaning of a high energy density is storing more charge than other batteries of the same size, this conveys that a high-density battery provide higher capacity, ultimately lasting much longer. This is practical for appliances and machinery where weight and less space occupation are important consideration factors.
The energy density of lithium-ion battery is much higher and there are factors affecting their long-lasting battery.
- High capacity: Generally speaking, the larger the capacity, the longer the battery can discharge.
- Low discharge current: The discharge current also affects the duration of the battery. Battery capacity/discharge current can get the discharge time of the battery.
- No memory effect: Memory effects in batteries occur by the reduction in the lifetime of a battery due to incomplete discharges previously. Lithium-ion batteries have no memory effect.
What factors affect energy density of battery?
The top 4 proven reasons affecting the energy density of a battery are as follows.
- Optimizing charge current
Keeping the current for charging controlled can help improve the lifetime of a battery. Otherwise, providing a high or low charge current can damage the internal reactions occurring within a battery and thus, reduce its capacity.
- Internal resistance
Low resistance means more easy flow between the anode and the cathode and ultimately better performance. For this, you need to create less resistance to boost performance. Using add-ons in the electrolyte can reduce the resistance and provide a better flow of ions. Vinylene carbonate is one of the best options to use for add-ons.
- Temperature
Exposing the battery to extreme temperatures affect its density. Charging it at extremely high or low temperatures can result in oxidation at the electrodes which can reduce the overall capacity.
- Aging
Unlike normal aging, the aging here is not only to consider the years of usage but the conditions you put the battery in which ultimately results in fast aging. These include overcharging, undercharging, or exposing them to extreme temperatures. These processes damage the battery electrolyte and reduce their capacity resulting in lower performance.
How do you increase the energy density of a battery?
Talking about increasing the energy density of lithium-ion battery, different strategies can be implemented. Starting off with the electrode engineering, which lessens the weight of inactive components of a battery such as a binder and a separator and thus, improves the energy density. This occurs as a by-product of mass loading on electrodes, hence providing more capacity and energy density to a lithium-ion battery.
Another method is laser perforation. This process creates pores in the electrodes of a lithium-ion battery and significantly improves the energy density of the battery due to the rational distribution of the surface. The improvement in the chemistry of a lithium-ion battery from laser perforation has been scientifically proven.
Greeny
I am an experienced author in the lithium battery and electric two-wheeler swapping industries. I hold a bachelor's degree in Electronic Engineering from a prestigious university and have conducted in-depth research in lithium battery technology and battery swapping systems. I have worked as a battery engineer at a renowned power battery company and have been involved in the design and operation of electric two-wheeler swapping stations. With years of professional experience, I have gained a deep understanding of the industry's trends and market demands.
My commitment is to share my expertise and knowledge accumulated in these fields with readers. Through my writing, I aim to provide insights into industry dynamics, technological trends, and future development directions. I strive to help readers better comprehend the industry's updates and make informed decisions.
Thank you for your attention and support. I look forward to exploring the fascinating world of the lithium battery and electric two-wheeler swapping industries together.
All Posts
Related post
Leave a comment