January 5, 2024

Vikram Sarabhai Space Centre (VSSC)/ISRO has qualified 10 Ah Silicon–Graphite anode based high energy density Li-ion cells as a low weight and low cost alternative to present cells being used. The flight demonstration of the cells as a battery was successfully completed by powering a resistive load on-board the POEM-3 platform of PSLV-C58. The on-orbit voltage, current and temperature values of the battery were acquired through telemetry and found to match well with the predictions.

Compared to conventional Li-ion cells which use pure graphite as anode material, this cell uses Si-Graphite composite as anode material. This helps in accommodating more Lithium ions for a given unit mass of anode material and thus improves the energy density of the cell. In addition to the material change, this cell also employs cost effective hardware which are readily available and a crimped sealing based design which reduces the hardware cost and fabrication cost significantly. The energy density of the Silicon High energy Li-ion cells is 190 Wh/kg with an operating voltage of 4.2 to 2.8 V, against Lithium-ion cells (157 Wh/kg). During flight the battery system worked for 21 hours in 15 orbits delivering a capacity of 8.9 Ah with final drained voltage of 0.4 V.

Before inducting any new systems in operational vehicles &missions, VSSC subjects the system to rigorous qualification and flight demonstration as piggy back payloads. Same approach is followed for these cells also. The capability of the cells to survive and perform in harsh space environment was also successfully demonstrated through the POEM experiment.

Based on the confidence gained through this performance, these cells are poised to be used in upcoming operational missions where 35-40% battery mass saving is expected. The system find application both in space and ground use.