Thursday 20 December 2012

Tencel for Battery Applications

Marco Gallo of Lenzing AG, Lenzing (Austria) described the development of separators for alkaline batteries using Tencel.  Tencel can be refined in disc refiners and beaters to give a hgher proportion of microfibers and fewer cut fibres than pulps.  This leads to lighter, thinner papers with smaller pores and hence better insulation and conductivity than alternatives.  Cellulosics are normally blended with PVA fibres and bonded with PVA latex.  Tencel can be used in blend with pulp or viscose in the cellulosic portion according to the cost/benefits required.
New varieties of Tencel are under development which will allow further reductions in the weight of the separator required per battery.  These also improve the dimensional stability and durability of the paper in the strong alkalis used.  There were numerous questions:

  •         Can Tencel be used to obtain nanofibres?  Yes but at a cost which only works for some applications.
  •          What operating temperatures must the separator be designed for? -30 to +50C
  •          Is the whole furnish refined together?  No Tencel is refined separately.
  •          Is Tencel paper used in double-layer electrolytic capacitors?  Yes.
  •          Are fibrils lost through the wire?  Yes this is an issue which necessitates careful tuning of the refiner.
  •          Would Tencel be used in electric car batteries?  Yes – this is under development.

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