Internal pressure regulation enables reliable electrochemical performance evaluation of lithium-ion full coin cell

Graphite-based full coin cells provide a more resource-efficient way to evaluate the electrochemical performance of materials compared to commercial lithium-ion batteries (LIB). However, in graphite-based coin cells, the inevitable internal pressure will affect the accurate evaluation of material electrochemical performance by inducing degradation of the active particles, altering the electrode pore distribution, and hindering ion transport, etc. This study uses an in-house tool to regulate and detect the internal pressure of coin cells, to minimize the negative impact of internal pressure on performance evaluation. Optimization of the internal pressure in the coin cells greatly improves materials-evaluation reliability in the capacity consistency, rate performance, and cycling stability. Under optimal internal pressure of 77 kPa the testing high-capacity electrodes achieve an excellent capacity consistency standard deviation of 0.66 mA h g−1 and a high capacity retention rate of 93.3% at 0.5C. Kinetics and thermodynamics analyses show that the loss of active lithium and polarization can be suppressed at optimal internal pressures, resulting in optimal electrochemical performance. The findings will provide general guidelines for the design and preparation of full coin cells for reliable evaluation in LIB.