On August 25, 2026, Maxell announced a wireless-charging solid-state battery module matching the size and output voltage of a 1/2AA-format thionyl chloride lithium (ER) battery. The module packs a solid-state battery, a boost circuit, and a receiver circuit into a housing measuring 14.5mm in diameter and 25.2mm in height, outputting 3.6V. Two versions are available, rated for maximum temperatures of 125°C and 150°C respectively. However, both remain development products, and their "compatibility" with existing ER batteries extends only to dimensions and voltage—not to capacity or operating time, meaning they cannot simply replace existing batteries in any device.
Fitting a Battery and Two Circuits into a 1/2AA Form Factor
The new modules come in two variants: a 125°C-rated version using the mass-produced solid-state battery "PSB401010H," and a 150°C-rated version using the developmental "PSB401010T." Both output 3.6V and share the same 14.5mm-diameter, 25.2mm-height housing. Standard capacity measured at a 1mA load is 3.6mAh for the 125°C version and 2.7mAh for the 150°C version.
| Published Specification | 125°C-Rated Version | 150°C-Rated Version |
|---|---|---|
| Cell Used | PSB401010H (mass-produced) | PSB401010T (developmental) |
| Output Voltage | 3.6V | 3.6V |
| Standard Capacity (1mA load) | 3.6mAh | 2.7mAh |
| Operating Temperature Range (1mA load) | 0–125°C | 0–150°C |
| Charging Time (25°C) | 5.0 hours | 5.0 hours |
| Dimensions | 14.5mm dia. × 25.2mm height | 14.5mm dia. × 25.2mm height |
This table reveals a clear trade-off between high-temperature tolerance and capacity. While the upper temperature limit rose by 25°C (from 125°C to 150°C), capacity dropped by 0.9mAh, or 25%, from 3.6mAh to 2.7mAh. Even with matching 3.6V output, actual runtime per charge will vary depending on a sensor's standby current, measurement intervals, and peak current during wireless transmission. Maxell has not disclosed capacity characteristics at loads other than 1mA, maximum output, or charge-discharge cycle life. Evaluating actual load profiles will be necessary before adoption decisions can be made.
The predecessor ER-compatible module, announced in January 2026, measured 17.9mm in diameter and 50mm in height, offered 35mAh capacity, and charged via USB Micro-B at 5V. The August announcement reduced capacity while shrinking the housing to the 1/2AA format and integrating a wireless receiver circuit. The core innovation here lies less in the solid-state battery itself and more in the module design that enables contactless charging for compact sensors.
Targeting Sealed Temperature Loggers for Retort Sterilization
Maxell has identified temperature loggers used in retort food sterilization processes as its initial target application. High-temperature food manufacturing processes demand heat-resistant electronics for temperature recording. Additionally, minimizing openings for battery replacement or wired charging helps reduce moisture ingress. The ability to charge from outside the housing makes it easier to maintain a sealed structure.
Maxell is jointly validating practical applications with House Foods using food temperature loggers. The official program for the 27th Annual Meeting of the Japanese Society of Food Engineering lists a Maxell presentation titled "Development of a Solid-State Battery Module for Temperature Loggers," scheduled for August 31, 2026, at Industrial Plaza. The presenters are Toshihiro Araki and Yuji Honda.
Currently, only the fact of joint validation and the upcoming presentation have been disclosed. The number of loggers used, sterilization temperatures and hold times, and temperature measurement accuracy remain unknown. The communication method and waterproofing performance of the housing are also unpublished. Consequently, no data yet exists to support causal claims about measurement accuracy or durability in food processing applications. Inclusion in a conference program differs from publication in a peer-reviewed paper—this remains at the stage of a corporate presentation.
"Approximately 5x" Should Not Be Equated with 150°C Compatibility
The 150°C-rated version builds on electrode design changes Maxell announced in 2024. The company identified side reactions occurring at the interface between the positive electrode active material and solid electrolyte as the primary cause of high-temperature degradation, then revised the electrode materials and composition accordingly. In internal testing using the PSB401010H housing, Maxell set conditions of CCCV charging at 8mA/2.6V and constant-current discharge at 8mA with a 3% DOD cutoff at 150°C. DOD refers to depth of discharge; this test condition discharges only 3% of capacity per cycle.
According to published graphs, the point at which discharge cutoff voltage dropped to near 1.0V occurred at approximately 250 cycles for the conventional electrode specification and approximately 1,300 cycles for the new electrode specification. Maxell describes this difference as "approximately 5x." This change from roughly 250 to roughly 1,300 cycles represents experimental results obtained under limited cell test conditions—150°C, 8mA, 3% DOD cutoff. It is not a figure demonstrating that the newly announced module, complete with receiver and boost circuits, can operate five times longer in actual food processing environments.
Confusion with simulation values should also be avoided. The 2024 comparison represents experimental data, not theoretical prediction. However, the number of test cells, independent repetition counts, margin of error, and third-party verification cannot be confirmed from published materials. Sufficient material for evaluating reproducibility is lacking.
Peer-Reviewed Paper Explains Degradation Mechanism; Product Lifespan Data Remains Unpublished
Regarding degradation mechanisms in solid-state batteries, Maxell researchers Kazuki Furukawa and Masayuki Yamada, along with Kingo Ariyoshi of Osaka Metropolitan University, published a paper in the peer-reviewed journal Journal of Power Sources in 2025. Titled "Quantitative analysis of side-reaction rates and capacity fading mechanisms in all-solid-state Li-ion batteries," the paper appears in volume 643, article number 237001, with DOI 10.1016/j.jpowsour.2025.237001.
The experiments used test cells combining a lithium cobalt oxide (LCO) cathode, a lithium titanate (LTO) anode, and an argyrodite-type sulfide solid electrolyte. Electrode diameter was 9mm, the solid electrolyte layer measured 16mm, applied pressure at the electrode surface was 4MPa, and the primary test temperature was 105°C. In long-term testing, the first two cycles were measured at 0.25mA, the following 100 cycles at 1.5mA, and the final three cycles again at 0.25mA. The number of independent cell repetitions is not specified in the available experimental methodology.
The research team reported that, for the solid-state cells evaluated, capacity decline was governed more by state-of-charge (SOC) imbalance between the positive and negative electrodes than by degradation of the materials themselves. Using symmetric cell experiments, they calculated side-reaction currents for each electrode and presented a theoretical model linking SOC imbalance to capacity fade. This peer-reviewed research, combining experimentation with modeling, suggests potential improvements in predicting high-temperature battery lifespan. However, it did not test the 1/2AA module, wireless charging reception, or retort sterilization processes. The mechanisms identified in basic cell research should be read separately from guarantees about the lifespan of the complete product.
Practical Deployment Hinges on Load Conditions and Housing Materials
The dedicated charger operates on 5.0V USB power input and automatically stops after 5 hours. Its operating temperature range is 0–40°C, with dimensions of 65mm length, 52mm width, and 38mm height. Even though the module itself operates at 150°C, the charger is not rated for that temperature. Based on published specifications, the intended usage pattern involves charging outside the high-temperature process, then relying on stored power during the process itself.
The term "wireless charging" also comes with caveats. Maxell notes that certain housing materials may prevent power transfer, and states that chargers require dedicated designs tailored to each host device. The company has not disclosed compatibility with general standards like Qi, nor has it specified transmission distance or efficiency. This is not a component that can be retrofitted onto existing equipment without qualification.
Launch timing, pricing, and mass production plans remain unannounced. How much battery waste this technology can ultimately reduce will depend on how many times a single module can be recharged, how many years it can serve in field conditions, and the operational burden of managing dedicated chargers. If the August 31 presentation reveals real-world process conditions and results—and if operating time by load profile and full-module cycle life are subsequently published—the advantages of the 1/2AA format could translate into concrete design decisions for food factories and IoT devices.