High Power Rechargeable Thermal Battery
Abstract
Report developed under STTR contract; a proof of concept for a portable, rechargeable thermal battery (RTB). Including a superinsulated case, a lightweight (10 lb) RTB can provide 250W for 2-6h at 140 Wh/kg with days of activation between recharging. It can also provide 1 kW pulses (30s) throughout its capacity The RTB at 10 lbs 250W fills a gap in power supply capability for ARMY field operations under which motor generators cannot be down-sized (about 40 lbs). Three accomplishments have lead to the portable RTB. (1) Increased specific energy by way of high rate, thick electrode LiAl/FeS2 with CuFeS2 cells. (No Ni or Co content); (2) A vacuum-insulated case enables versatility (3W heat loss for days of operation, no heat signature); and (3) High durability under abusive field conditions (safety discharge to 0 volts, no overheating at full power). Durability and safety are key features of the Phase I demonstration. A 4-cell battery RTB was operated for 140 cycles under full capacity, constant power discharges. More than twenty thermal cycles, some deactivations during charging or discharging, showed no ill effects. (It uses MgO powder separator). Overcharging and overdischarging posed no safety problems. The RTB has inherent battery charge/discharge balancing which remains a problem for Li-ion, Li/polymer batteries. Also RTB has no organic or Ni/Co compounds which avoids toxicity and explosion hazards. Improved RTB design gives prospect for low cost commercial battery applications. The elevated operating temperature of RTB provides a unique symbiotic-type technology with cheap getters (gas absorbers) forming/sustaining the vacuum insulated housing and dramatically-extending the operating life for 2-3 days after activation. It is immune to hot/cold ambient temperatures, and can be operated continuously with periodic charging. A 25 year shelf life can be anticipated.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 15, 1997
- Accession Number
- ADA362298
Entities
People
- Thomas D. Kaun