In this blog post, we’ll explore the principles behind wireless charging—which emerged as a solution to the inconvenience of cables—as well as the characteristics of magnetic resonance and magnetic induction methods. We’ll also examine the potential of wireless charging technology as it expands beyond smartphones to encompass a wide range of electronic devices and everyday environments.
What’s the most popular seat in a café? You might think it’s a spot with a nice view or a quiet place to relax, but you’d be wrong. The correct answer is the seat with an outlet. In today’s world, where it’s hard to live without various portable electronic devices like smartphones, tablets, and laptops, charging is a non-negotiable issue. While power banks offer an alternative, we still can’t completely escape the constraints of cables. From broken cables and faulty connectors to the competition for charging spots at cafes, traditional charging methods present one challenge after another. “Wireless charging” has emerged as a technology to solve these inconveniences.
Wireless charging technology can be broadly divided into magnetic resonance and magnetic induction methods. Both methods utilize the basic principle of electromagnetic induction. Electricity and magnetism are closely linked, so a change in one affects the other. A classic example is how a magnetic field is generated around a current-carrying wire, and this magnetic field affects the direction of a compass. Conversely, a changing magnetic field can induce a current in a conductor. This is Faraday’s law of electromagnetic induction, and using changes in the magnetic field to induce electricity is the fundamental principle behind wireless charging technology. In this process, coils serve as the medium for generating and transmitting these changes in the magnetic field. When a current flows through one coil to generate a magnetic field, and this magnetic field affects the other coil, a current is induced in the opposing coil. The difference between the two wireless charging technologies lies in how these coils are utilized and under what conditions and at what distance the magnetic field is transmitted.
The magnetic resonance method transmits power via a magnetic field by tuning the coils to a resonant frequency. When a current-carrying coil forms the same resonance conditions as the opposite coil, energy can be transferred between the two coils. A key feature of systems tuned to the same resonance frequency is that they can resonate with each other even at a certain distance, allowing power to be transferred without the coils needing to be in exact contact. Therefore, as magnetic resonance technology advances further, it may become possible to charge multiple electronic devices simultaneously within a single charging area. In fact, the AirFuel Alliance is currently developing technology—called AirFuel Resonant, which uses magnetic resonance—to supply power to multiple devices simultaneously without requiring precise alignment of the charging positions. The goal is to charge various devices, such as smartphones and laptops, while maintaining a certain amount of spatial clearance on the charging surface.
However, magnetic resonance technology faces challenges that need to be addressed, including power loss, efficiency, charging range, and the influence of the surrounding environment. Power transfer efficiency can vary depending on the position and distance between the transmitter and receiver coils, as well as the surrounding environment; electromagnetic fields generated during wireless power transfer and related safety concerns must also be taken into account. Furthermore, since radio wave and electromagnetic field standards and certification requirements differ by country and region, both regulatory and technical conditions must be met to commercialize the technology on a large scale. The A4WP, which previously led the development of magnetic resonance technology, merged with the PMA in 2015 to form the AirFuel Alliance. Currently, the AirFuel Alliance is promoting standardization and technological development centered on next-generation wireless power technologies, such as magnetic resonance and RF methods. In particular, AirFuel Resonant highlights spatial freedom—the ability to charge multiple devices without precise positional alignment—as its key advantage.
Magnetic induction is a wireless charging technology, but it is primarily effective at close range. This technology, which has also been used in electric toothbrushes, transmits power via a magnetic field by placing two coils in close proximity. In other words, power is transmitted directly through electromagnetic induction between the two coils, without any separate transmission medium between them. Therefore, the charging pad and the smartphone must be placed close together. Unlike methods that use resonance frequencies to transmit power over relatively wide distances, magnetic induction induces power directly at close range. While spatial flexibility is limited because the device cannot be placed far from the charging pad, this method offers the advantage of being easy to implement in practical applications. The implementation is relatively simple and has long been used in commercial products; the Qi standard established by the Wireless Power Consortium (WPC) is a prime example. Qi has continued to evolve since its first specification was announced in 2010, and Qi2 was introduced in 2023. Qi2 improved alignment issues by introducing a method that uses magnets to align the charger and the device; in 2025, Qi2 25W, which supports higher output than the existing Qi2, was announced. As of 2026, the WPC is also developing the Qi2 50W standard, which supports even higher power output. In June 2026, a technical conference attended by several global companies validated the technical proposal and prototypes for Qi2 50W. However, Qi2 50W has not yet been finalized as a commercial standard; it is currently in the process of being developed as the next-generation specification.
Of course, it is no longer accurate to view wireless charging as a technology that is difficult to adopt on a mass scale, as was the case in the past. Wireless charging is already widely used, particularly for smartphones and wearable devices, and the adoption of Qi2 is expanding rapidly. According to the WPC, more than 1,200 Qi2-related products were certified in 2025 alone, and products supporting Qi2 25W are now beginning to appear in earnest in 2026. Furthermore, Qi2 25W supports approximately 70% more power than the previous Qi2 15W standard, and some certified products can now charge from 0% to 50% in about 30 minutes. Early wireless charging earned the unfortunate nickname “cool junk” due to its slow charging speeds, the need for precise alignment, and issues with heat generation and efficiency; however, technology is now rapidly advancing to overcome these limitations. In addition to advancements in magnetic resonance and magnetic induction methods, alignment technologies using magnets and higher-output charging standards continue to emerge. Just as the furniture company IKEA integrated wireless charging capabilities into its furniture, bringing the technology into everyday living spaces, wireless charging is no longer limited to simply charging smartphones. Research is also ongoing into the concept of applying wireless charging technology to roads, which could create an environment where electric vehicles receive power even while driving. It is easy to imagine how much could change: rooms free of cluttered cables, living spaces with reduced dependence on charging cables, and environments where charging infrastructure is integrated into roads and vehicles. Wireless charging is not merely a technology that eliminates a single cable; it is a technology that transforms the very way power is transmitted. Let’s watch to see what changes wireless charging technology will bring in the future.
