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| Fig. 1: Diagram of how a Li-ion battery functions. (Source: Wikimedia Commons). |
The modern smart phone functions as the medium by which society functions as it handles innumerable forms of communication and mediates human interaction, while also acting as a source of entertainment and consumption. Considering the impact of the smart phone, nothing is more important than the battery that keeps these devices running, thus keeping daily life functioning. Without sacrificing phone performance, battery life is difficult to improve, as the ability to expand the Li-ion battery is currently limited. However, the layered anode and cathode sheets and liquid electrolyte that creates these batteries isn't done improving. The creation of greater battery life in today's culture is synonymous with a higher-functioning society, so the benefits of such advances cannot be understated.
Basic lithium-ion batteries have struggled to match the incredible expansion of internal processors, creating an imbalance between phone capabilities and battery life. Seemingly every day, a new feature is added to the already-impressive list of smart phone capabilities, but at the cost of shortened battery life. A Li-ion battery consists of a sealed bag of specifically layered anode and cathode sheets with separators in between. A liquid electrolyte permeates all of those layers and allows for ionic movement that creates energy. [1] The energy is created by ions moving from anode to cathode, and the amount of power a given battery can hold is thus based on how many ions can be contained in any single anode or cathode (Fig. 1). Here, the process of linear diffusion is described as the change in concentration as a function of distance and time. Because these batteries often contain lithiated metal oxide positives and carbon negatives, they have high cell voltages that directly relate correlate to high energy density. [2] The problem with Li-ion batteries is that they immediately begin degrading from the minute a smart phone turns on. Over time, the anodes and cathodes can't fit the same number of ions they once could, and this process is only exacerbated further if users allow their batteries to die completely on a regular basis. [2]
Another issue with the batteries can be attributed to the amount of energy they store. This number is and has been relatively the same, and changes to it create additional issues. Apple has continued to increase the mAh (milliampere hour) with each new generation of phones it releasesThe problem with Li-ion batteries beyond the fact that they are always degrading is that one solution only leads to another problem. Phones with smaller batteries have a shorter charge time. However, with a battery with a higher mAh, it takes far longer to charge. Also, a bigger battery means a less-compact phone, a feature that many consumers value today. [1]
Although the Li-ion battery hasn't upgraded the amount of energy it can store by an incredible amount, progress has been made in a different route - the charger. Batteries now charge and recharge in around half the time they used to. This is less from the actual battery technology and probably more closely tied to the technology of the chargers. [2] There is a balance, however, because a charger with too many watts has the potential to destroy a Li-ion battery. [3] Other technological advances may begin to aid phones in how they are able to charge and conserve battery life over time by alerting users of when the phone may not last from one charge to the next. [4] Another challenge relates to continuing the increase of battery life without too large an increase in the size of the battery itself. In the future, companies are looking to revolutionize charging through software updates that prompt a phone and its charger to interact and optimize the amount of energy necessary to push ions back to the anode. [2] Either way, under the status quo, Li-ion batteries should continue to improve, therefore continuing to advance the way technology affects daily life. [1]
© Sam Werner. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] M. Yoshio, R. J. Brodd, and A. Kozawa, eds., Lithium-Ion Batteries (Springer, 2009.
[2] E. Limer, "8 Essential Tips To Keep Your Phone's Battery Healthy," Popular Mechanics, 26 May 15.
[3] N. Ravi et al., "Context-Aware Battery Management for Mobile Phones," IEEE 4517397, 17 Mar 08.
[4] E. Eason, "Smartphone Battery Inadequacy," Physics 240. Stanford University, Fall 2010.
