Why do most universities only produce coin cell batteries?

Technical Threshold and Cost: The "Low-hanging fruit" of coin cell Batteries

The most core advantage of the coin cell battery lies in its irresistible "three highs and three lows" characteristics.

High throughput: Dozens or even hundreds of battery cells can be easily prepared in a single experiment, meeting the massive demands of material initial screening and condition optimization. This scale effect is irreplaceable when exploring new materials and new formulas.

High standardization: CR2032 coin cell cases, standard separator, fixed electrolyte volume, and simple tablet assembly process - the highly consistent physical form minimizes performance fluctuations caused by human operation and structural design, and the data is highly comparable.

High data comparability: Thanks to standardization, performance data (such as capacity and cycle life) based on power deduction among different laboratories and different literatures are relatively easy to be compared horizontally, becoming a "universal currency" for academic exchanges.

Low cost: The material cost of a single battery (excluding research and development) is only a few to tens of RMB. In contrast, assembling a pouch or cylindrical battery with a complex process that requires packaging equipment can cost tens or even hundreds of times more.

Low technical threshold: Assembly can be completed in a glove box without the need for expensive large-scale industrial equipment such as winding, liquid injection, formation, and packaging, significantly reducing the requirements for laboratory space and personnel skills.

Low time consumption: From the preparation of materials to the completion of power-on assembly and the start of testing, it usually only takes a few hours. The production of pouch cells, from the preparation of electrode sheets to the final test readiness, may take several days or even longer. In the scientific research competition that pursues rapid iteration, time is output.

These advantages make coin cell batteries the "most effortless lever" for university researchers, especially graduate students with limited resources, to explore the intrinsic properties of materials within limited time and funds. It is like a sharp and lightweight scalpel, allowing researchers to relatively "purely" analyze core scientific issues such as the reaction mechanism, capacity potential, and kinetic characteristics of the electrode material itself.

Academic system: The powerful shaping by the Invisible Hand

However, the prevalence of power cuts is by no means driven solely by technological convenience. The current academic evaluation system is like an invisible giant hand, profoundly shaping the preferences for research topics.

Impact factor orientation: One of the core driving forces for university research is to publish high-level papers (such as Nature, Science, JACS, AM, etc.). Top journals are almost exacting in their pursuit of "novelty" and "breakthrough". Rapidly verifying the high specific capacity, long cycle life or unique mechanism of a new material in a power-off system is far more likely to produce "impressive" data and attract the attention of editors and reviewers than slowly advancing engineering optimization in complex battery systems. An article demonstrating "new materials achieving astonishing performance in battery discharge" has a much lower difficulty and speed of publication than an engineering optimization paper titled "Mature Materials achieving a 10% performance improvement in practical Batteries".

The postgraduate training period is short: master's students usually only have 2 to 3 years, while doctoral students take about 5 years. It is extremely stressful to complete the topic proposal, experiments, thesis writing and defense within a limited time. The short cycle and quick result feedback of the power-off experiment make it inevitable for postgraduate students and their supervisors to give priority to research tools that can quickly accumulate data and reduce the risk of delayed graduation under the pressure of graduation.

Equipment dependence and path locking: The purchase of equipment in university laboratories often revolves around mainstream research directions. Once a complete circuit breaker preparation and testing platform is established, subsequent research naturally tends to continue using this mature system. Purchasing large-scale battery pilot lines or complex packaging equipment not only incurs high costs but also requires professional operation and maintenance personnel, which is an excessive burden for most research groups. This has led to a path dependence of "conducting research on whatever equipment is available", further strengthening the dominant position of power cuts.

A "safe" haven: Compared with the safety risks such as gas expansion, leakage, and thermal runaway that may exist in complex battery systems (such as large-capacity pouch batteries) during testing, the battery is much safer due to its small capacity (usually <10mAh) and robust structure. This is an additional point that cannot be ignored in the university environment with strict safety management.

Industrial Divide: The Arduous Leap from "miniature bonsai" to "towering trees"

The "excellent performance" derived from power-off in university laboratories is often regarded by the industrial sector as a carefully cultivated "miniature bonsai". There is a huge gap between its glamorous data and the actual demand for power batteries or energy storage batteries:

The structural differences are huge: The positive and negative electrodes of the battery are stacked face to face, while the internal structure of the practical wound/laminated battery is much more complex, with problems such as bending stress, interface contact differences, and uneven current distribution. Materials that perform well during power-off may experience a sudden decline in performance or even failure in the complex mechanical and electrochemical environment of practical batteries.

The process gap: The battery is made by dry-pressing a very small amount of material powder into sheets, which is completely different from the actual battery production processes such as slurry coating, roller pressing, and slitting. Laboratory tablet pressing cannot simulate the real effects of industrial roller pressing on electrode porosity, binder distribution and the formation of conductive networks. Many materials that perform well in tablet pressing may be unable to be applied in the coating process due to poor stability of the slurry or weak adhesion to the current collector.

Test condition distortion: Power-off tests typically employ extremely low current densities (such as 0.1C, 0.2C), mild temperature ranges, and shallow charging and discharging, among other idealized conditions. Practical batteries, however, need to operate stably under harsh conditions such as high charging rates (fast charging), wide temperature ranges (-30℃ to 60℃), deep charging and discharging, and long-term cycling. The "long cycle life" and "high rate performance" measured during power-off often shrink significantly under actual working conditions. Research comparisons show that the capacity retention rate of the same material after 500 cycles of power-off may be 90%, but it may only drop to 70% in soft packages.

Key engineering issues are missing: The power-off system completely avoids the crucial engineering challenges in practical batteries: electrolyte consumption and replenishment, gas production management, expansion stress, thermal management, packaging reliability, consistency and yield control, etc. These problems are often the core bottlenecks of industrialization, but they are systematically ignored in the research based on power deduction in universities. A senior battery engineer once sharply pointed out: "Power-down data is like a fairy tale, very beautiful, but has nothing to do with the real world." What we are more concerned about is whether the material will burst the shell in the 100Ah battery or whether lithium will precipitate during fast charging.

This disconnection has led to a large number of research achievements from universities becoming "empty talk on paper". What the industry needs is not materials with the "highest specific capacity" in laboratories, but materials and process solutions that can maintain stable performance, controllable costs, and safety and reliability in large-scale manufacturing.

The phenomenon that battery research in universities is "dominated" by coin cell batteries is the result of a complex game among the logic of scientific research efficiency, academic evaluation mechanisms, resource limitations and the actual industrialization demands. As a powerful tool for basic research, the value of power-off is beyond doubt.