Saft is developing within the frame of the ARTES 8 Alphabus contract a "high specific energy cell". The purpose of this cell is to reduce the battery weight for the Alphabus satellite. The objective is to increase the specific energy by more than 25% of the existing VES140 cell. The specific energy target for the VES180 is 170 Wh/kg.
The development includes two main phases:
1. Validation of the mechanical design using the VES140 electrochemistry by performing a formal qualification of the VES140SA (A for 'attached'). This cell includes the modification of the VES140: the jelly roll is attached to the positive terminal and fixed in the tube for any vibration levels. See the picture of the internal view of the cell. This phase is close to the CDR of VES140SA.
2. Qualification of the new electrochemistry that leads to the increase of the specific energy. The electrode active materials, composition and thickness are change versus VES140.
click for larger image
The Key issues are :
- The qualification of the VE180 cell with high specific energy (>170 Wh/kg) in May and June 2005,
- Manufacturing the first batch for the Alphabus satellite
The main benefit is to save 50 to 60 kg at battery side with the improved specific energy.
The Cell specification summary is the following:
- Energy: 170 Wh at EOCV=4.1 V and C/1.5
- Specific energy: 160 Wh/kg at EOCV=4.1 V, C/1.5, 30 °C
- Energy loss:
- 15 years GEO 90 % DOD: cycling <2%; calendar<2 %
- 5 years LEO 30 % DOD: cycling <20 %: calendar<1%"
- Voltage range: 2.7 to 4.1 V
- Temperature range: 0 to 40 °C
- Vibration levels: loads of typical launchers
- Leak rate: 10-7 cm3.atm/s
|The VES180 performance increase is shown in the following graph where it is compared with the VES140:|
The development schedule is as follows:
- Electrochemical design PDR was held 8th December 2003,
- The VES140SA and VES180SA mechanical PDR was held 15 April 2004,
- The CDR VES140SA was held 18th November 2004,
- The CDR VES180SA is scheduled in May 05. The first EMs have been manufactured and are currently performing the first validation for the CDR,
- The QM cells are manufactured and have been prepared for qualification. The QR is scheduled in July 05.
The Qualification Review for VES140SA was held satisfactorily with minor actions in July 2007. The qualification will be made official by the board.
The Final Qualification Review for VES180SA is foreseen for May 2008. An intermediate Qualification Review is scheduled mid January 2008 for head down configuration.