Description
*On Delegation Request (formerly called Priority 2)
Objective: The objective is to develop a battery cell with 30% more specific energy at beginning of life, compared to the currently qualified Li ion cell, and with a capacity fade of 10% or less at end of life.
Targeted Improvements: Reduction of the mass and size of the flight GEO battery by 25%, depending of the capacity fade under the mission conditions. Maintaining European cell manufacturers worldwide leading position for space battery cells.
Description: The battery of GEO spacecraft contributes largely to the mass of the power sub-system. Decreasing the mass and volume of the battery will freespace and mass to accommodate payloads. SAFT VES180SA Li ion cell (155Wh/kg) has been developed and qualified under ARTES 8, and itis used in many GEO telecom satellites.
An evolution of the cell, SAFT VL51ES, is available for Telecom satellite platforms. However, it offers a modest specific energy increase compared to SAFT VES180SA. Increasing the specific energy of battery cell is challenging. Several TRP activities on electrochemical couples offering 250 Wh/kg or more have shown how difficult it is to increase significantly the specific energy of an electrochemical cell while preserving the other properties of the current state-of-the art Li ioncell (high cyclability, low self-discharge, high round-trip efficiency). Thus, an intermediate step, i.e. a Li ion cell with a specific energy around 220 Wh/kg at beginning of life is of interest for GEO platforms as it will allow to reduce the mass of the battery by about 25%. The current Li ion cell chemistry, based on insertion electrodes, can be modified to reach a specific energy higher than the one offered by the GEO space cell. High specific energy Li ion cells are available on the terrestrial market, like the Panasonic NCR18650B that offers 260 Wh/kg specific energy. But such cell is designed to be used at low depth of discharge, and not at high depth of discharge as requested by GEO missions.
In the proposed activity, the specific energy increase will have to be addressed, and also many other properties like ageing (cycling calendar), efficiency, temperature range, self-discharge, balancing, by-passneed. To further reduce the battery size, the new cell shall be capable to withstand some overcharging during the 15 years GEO mission.The battery is sized to meet the worst conditions of the longest eclipse with max RF transmission over lifetime, with margins. If overcharge is permitted, the battery could be designed to meet the majority of the possible operating conditions, leading to an optimisation of the battery size. The overcharge conditions and limitations shall be defined (maximum overcharge allowed, how many times per mission, maximum duration, depth of discharge, temperature). Li ion cell engineering models shall be designed, developed, manufactured and tested to validate the design concept and the expected performance improvements.
Procurement Policy: C(2) = A relevant participation (in terms of quality and quantity) of non-primes (incl. SMEs) is required. For additional information please go to EMITS news "Industrial Policy measures for non-primes, SMEs and RD entities in ESA programmes".
*On Delegation Request (formerly called Priority 2) activities will only be initiated on the explicit request of at least one National Delegation.