CIO Co., Ltd. announced on September 18, 2026 the "SMARTCOBY ULTRA SLIM SS5K," a semi-solid-state power bank that packs 5000mAh of capacity into a body about 6.83mm thick, and launched the project on the crowdfunding platform Makuake[1]. The power bank supports magnetic wireless charging so it can be attached directly to a compatible smartphone, and its proprietary "NovaCore C3" safety design lets users check the battery's condition through a dedicated app[1].

Shaving Away 0.01mm at a Time

Power banks in the 5000mAh class usually get thicker as capacity increases. CIO previously ran a 3000mAh model called the "SMARTCOBY ULTRA SLIM 3K" on Makuake in 2025[2], and the new "SMARTCOBY ULTRA SLIM SS5K" builds on that experience, aiming to raise capacity to 5000mAh while keeping the same emphasis on thinness[1].

CIO says it reviewed every component — the casing, battery cell, internal structure, circuit board, and the surface that attaches to a phone — down to increments of 0.01mm. The exterior uses stainless steel, which keeps its rigidity even when machined thin; the casing itself is only about 0.30mm thick. The device comes in silver and black[1].

Semi-Solid Cells and Multiple Safety Tests

The battery cell, which has the biggest impact on overall thickness, is a semi-solid-state cell about 4.87mm thick. CIO says what matters is not the semi-solid format itself but which tests the cell has actually passed, and it lists short-circuit testing, high-temperature safety testing, drop testing, and crush testing among the safety checks the cell underwent[1].

"NovaCore C3" Makes Battery Health Visible

Battery degradation from repeated charge cycles is hard to see from the outside. The SMARTCOBY ULTRA SLIM SS5K addresses this with CIO's proprietary "NovaCore C3" safety design: connecting the device to a dedicated app over USB-C lets users check battery health, cycle count, and cell temperature during use. A built-in battery management system (BMS) also monitors voltage, current, and temperature, and throttles output if a set temperature threshold is reached[1].

Wireless Charging and Full Pass-Through Charging

The power bank supports magnetic wireless charging at up to 7.5W for compatible smartphones, plus a single USB-C port for wired charging at up to 20W. It also supports what CIO calls "complete pass-through charging," letting the device charge a phone wirelessly while the power bank itself is being charged. Plug the power bank in overnight, and both it and the phone can be topped up by morning[1].

CIO also designed the body's size and shape so it interferes less with a phone's camera module even when the phone is in a case, a detail specific to a battery meant to be worn stuck to the back of a smartphone[1].

Pricing and Lineup

The SMARTCOBY ULTRA SLIM SS5K's Makuake project began on September 18, 2026. The planned general retail price is 7,980 yen (tax included), with an early "super-super-early-bird" tier of 5,980 yen (tax included) limited to 300 units and a "super-early-bird" tier of 6,280 yen (tax included) limited to 500 units. Additional reward tiers are available; full details are on the Makuake project page[3].

Summary

CIO has announced the SMARTCOBY ULTRA SLIM SS5K, a 5000mAh power bank that comes in at roughly 6.83mm thick, and opened it for crowdfunding on Makuake. By combining a semi-solid-state cell, a battery of safety tests, and the health-monitoring "NovaCore C3" system, the product aims to balance thinness with safety. The planned retail price is 7,980 yen (tax included), with discounted pricing available for early backers.

Source [1]: https://prtimes.jp/main/html/rd/p/000000696.000043212.html

Source [2]: https://connectinternationalone.co.jp/cionews/crowdfunding/smartcoby-ultra-slim-3k/

Source [3]: https://www.makuake.com/project/ultra-slim-ss5k/