Nickel Cadmium Smartphone Batteries
Ibrahim Alahmari
ME 472
Due 11/21/2019
Nickel Cadmium Smartphone Batteries
Need Statement
Smartphones have become critical components of everyday living. They are used for major functions, including making calls and sending messages, social networking, browsing the Internet, and performing other vital tasks like shopping, booking flights, money transfer, monitoring the stock markets, keeping up-to-date with the news, and many different roles. Therefore, the smartphone must be on for an extended period, even when the individual is on the move. However, such functionality is limited by the batteries, which have a limited capacity, and which under intense usage even drains faster. Therefore, there is the need to explore strategies to make high capacity batteries with more prolonged per-charge usage, and that is also more durable. Such a battery should be made of Nickel Cadmium, which is so far the most reliable material among the available options.
Concept
Nickel Cadmium (NiCD) is inarguably one of the most preferred rechargeable battery systems materials for mobile phones. NiCD is preferred because it offers desirable qualities for phone batteries. The batteries are more durable, lighter, reliable, high performing, and economical. Therefore, they guarantee excellent performance at a lower cost (Morris & Tosunoglu, 2012). In the highly competitive smartphone market, where each product seeks to outdo the other in performance, NiCD batteries are the best option.
Smartphone batteries are unique in that they are small, slim, and light, but are required to handle high usage intensity. The battery component for the phone is compact because the device is held by hand and carried in the pocket compared to other devices like cameras and laptops that can be carried in a compartment or a bag. Latest phones support diverse functionalities, which also means that their energy usage is intense than other devices.
Embodiment
As will other rechargeable battery systems, NiCD operates on the principle that electrochemical reactions at the electrodes are reversible, which enables the storage of energy through charging and its release through discharging. During charging at the positive electrode, the electrical energy from a power source is stored as chemical energy through the conversion of the lower energy Ni(OH)2 + OH- to the higher energy NiOOH + H2O + e-. During discharge, the reversal occurs (Sullivan & Gaines, 2010). However, the NiCD battery is differentiated with the others in the way that cell pressure is managed. In other types of batteries, there is needed a mechanism to prevent the side reactions that releases gases that then increases the internal pressure and causes the cell to swell. The reaction is the leading cause of degeneration and eventual breakdown.
In sealed NiCD batteries, the internal pressure is maintained at safe levels during usage by increasing the capacity of the negative electrode in a process known as charge-reserve. The strategy ensures that once the battery approaches full charge, the positive electrode releases oxygen through electrolysis, which is then diffused to the negative electrode and is consumed through the oxygen recombination process with Cd and through reversal electrolysis, which then prevents the release of hydrogen and at the same time eliminates the oxygen. The same strategy is used to prevent hydrogen generation during discharge by using the same active material in the positive electrode (GP Batteries, n.a.). The technology makes the battery durable due to resistant to frequent charge and discharge and temperature variations. Therefore, they are the most effective to use in smartphones.
Detailed Analysis
Material Analysis
NiCD is one of the materials that have been used for the longest time in rechargeable batteries. Compared to the other elements, it is lighter, which allows for simple storage and transport. Most freight companies accept it without specific requirements. The downside of the material is that it is highly toxic and therefore, improper disposal poses risks for poisoning and damage to the environment (Breeze, 2018). It has a low memory, which needs regular exercising.
NiMH has been stabilized over the years by making alloys for use in batteries. The material is also suitable because it is environmentally friendly, by not containing toxic metals. It offers 40% higher energy density than NiCD, and there is potential for improvement. However, it is less durable due to the lack of tolerance to heavy load and high temperatures (Battery University, 2017). Therefore, it has reduced self-life and efficiency.
Lithium, particularly polymer and Li-ion, is preferred due to it is lightweight, which makes it ideal for making small batteries. It has high energy density and potential increase three-fold with improvement in electrode-active materials used, which reduces the quantity of material needed as they can run on a single cell. Li-polymer also has no memory, and therefore no maintenance is required. However, it has high reactivity and risk for fire. As a result, manufacturers are forced to use an additional protection circuit to reduce the risk, which reduces capacity (Breeze, 2018). There have been reported incidences of smartphones bursting and catching fire, which has caused injuries to users. The battery also suffers rapid deterioration, in the first year, and failing after two or three years, whether in use or not (Battery University, 2017). Therefore, it is not ideal for more intensity usage on a mobile phone.
Screening
NiCD has a lower energy density of between 45 and 80 Wh/kg, which is the lowest. However, it offers the highest cycle life of 1500, tripling the other batteries, has a fast charge time of one hour, and average overcharge. It also has a relatively higher self-discharge of 20%, temperature tolerance of -40 to 60°C, and peak load current of up to 20C. The battery requires regular maintenance through equalizing or topping charge each 30 to 60 days but has the lowest cost per cycle of $0.04 (Battery University, 2017). Therefore, it is more appropriate for smartphone energy needs.
Competitor material, NiMH batteries have a relatively higher energy density at a modest average of between 60-120 Wh/kg. However, the cells have a lower count cycle of between 300 to 500, low tolerance to overcharge, and moderate operating temperatures range of -20 to
60°C. The batteries have the highest discharge rate of 30% and a low load current of 5C. They also require regular maintenance after every 60 to 90 days but has a relatively her cost per cycle of $0.12 (Battery University, 2017). Therefore, they are not ideal for high-intensity use in mobile phones.
Lithium has a high-energy density of 100 to130 Wh/kg, which is the highest among the materials commonly used for smartphone batteries. It is also lightweight, which is another attractive characteristic. The battery has a low over-charge tolerance, load current peak of >2C, and small operating temperatures range of between 0 to 60°C, which makes it unsuitable for extreme conditions. It has a low cycle life of 300 to 500, which makes the battery to spoil fast and need for replacement. Therefore, it requires no maintenance but has the highest cost per cycle of $0.29 (Battery University, 2017). Spares are challenging to find and have even more reduced performance, which increases the batteries being discarded, increases the cost for the user, and possess risks to the environment.
Figure 1: Characteristics of Common Rechargeable Batteries
Ranking
NiCD is the top ranked material for smartphone batteries because it offers the most desirable qualities of fastest charge time, durability, reliability in extreme temperature, and lowest cost. NiMH is ranked second because it is also affordable, efficient in low temperatures, and high productivity due to high energy density. Lithium is ranked third because of high costs, short lifespan, and low tolerance to low temperatures and overcharge, which causes risks to users.
Product Specification
The proposed NiCD battery targets portability and high efficiency to allow for slim phones and space for other critical components. The product will be a 6V pack, with a maximum energy density of 80Wh/kg and a cell voltage of 3.0V. It will have a first charge time of one hour and target cycle life of 1500. It will also achieve the peak load current of 20C and the maximum operating temperature of between -40 and 60°C (Battery University, 2017). The high capacity is targeting advanced smartphones of the future with multiple functionalities such as high-resolution cameras larger screens, and operating systems.
Smartphones have become critical components of daily usage due to their multiple functionalities. The latest phones support advanced systems, which makes the individual dependent on them in most of their daily activities. However, the development is being hampered by the limitations of the current lithium batteries that deteriorates within a short time and also have reduced output. Therefore, a more efficient and durable NiCD battery is proposed.
References
Battery University. (2017). What is the best battery? Retrieved from https://batteryuniversity.com/learn/archive/whats_the_best_battery
Breeze, P. (2018). Power System Energy Storage Technologies. Cambridge, MA: Academic Press.
GP Batteries. (n.a.). NiCD technical Handbook: Nickel cadmium. Retrieved from http://www.scarpaz.com/Attic/Documents/NiCd.pdf
Morris, M., & Tosunoglu, S. (2012, November). Comparison of rechargeable battery technologies. In ASME Early Career Technical Conference, Atlanta, Georgia (pp. 2-12).
Sullivan, J. L., & Gaines, L. (2010). A review of battery life-cycle analysis: state of knowledge and critical needs (No. ANL/ESD/10-7). Argonne National Lab. (ANL), Argonne, IL (United States).
