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Advances in fast charging and wireless charging technologies are revolutionizing product design across various industries, including industrial equipment and electric vehicles. These advancements are creating new opportunities and markets (Figure 1). Lithium-ion rechargeable batteries capable of fast charging are particularly driving growth in sectors like electric vehicles, while also accelerating the adoption of wireless charging solutions.

For instance, the market for power tools equipped with fast-charging batteries is booming. The inconvenience of dealing with power cords in industrial equipment and electric vehicles makes wireless charging a critical component for expanding these markets. Industrial devices such as drones and industrial robots, along with electric vehicles operating on fixed routes like trams, buses, and commercial vehicles, are driving the integration of wireless charging solutions. This trend is driven by improvements in charging safety and user convenience.

Resonance-based wireless charging is gaining significant attention. MIT showcased a magnetic field coupled resonance technique in June 2007, followed by Intel's announcement of an electric field coupled resonance technique in August 2008. While the initial efficiency was around 40%, these methods hold promise for enabling in-motion charging, sparking ongoing research and development efforts.

The electric field coupled resonance method developed by Takenaka Works offers another promising approach. Unlike traditional electromagnetic induction methods, this technique allows power transfer even when the transmitter and receiver are slightly misaligned. Additionally, it avoids issues like overheating and electromagnetic interference. Despite requiring closer proximity between the transmitter and receiver, this method provides a safer and more reliable solution compared to current electromagnetic induction technologies.

Dr. Kazuo Hara from the Bamboo Institute of Technology envisions embedding wireless charging systems in factory floors, office spaces, and residential buildings. Such systems could power industrial robots, construction machinery, medical equipment, and household appliances. Furthermore, the goal is to develop a quick-charging system for electric vehicles that involves extending a boom to touch the vehicle during parking.

Takenaka Works' electric field coupled resonance system operates in two modes: series resonance and parallel resonance. Series resonance offers a simpler circuit configuration, while parallel resonance ensures efficient power transmission even at lower voltages. Both aim for a transmission efficiency of 95%. Series resonance has already demonstrated a 90% efficiency in transmitting 100W to an incandescent bulb at 600kHz. Parallel resonance, though still in the testing phase, shows potential for efficient high-power applications.

Fast charging has already proven successful in the power tool industry. The adoption of lithium-ion rechargeable batteries in power tools began around 2004-2005 and has grown rapidly. According to Makita, a leading power tool manufacturer, the global supply of lithium-ion battery packs surged from 1 million units in Q1 2005 to 13 million units in Q1 2008. This growth is attributed to the lightweight nature of lithium-ion batteries, their comparable power output to plug-in types, and their ability to charge fully in as little as 15 minutes.

Goto Zongli, head of Makita's development planning department, admitted initial skepticism about transitioning from nickel-metal hydride to lithium-ion batteries. However, the combination of superior performance, portability, and fast charging capabilities has made lithium-ion batteries a preferred choice for many applications. These advancements are setting the stage for even more innovative developments in the near future.

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