Merger and acquisitions by Apple. (Battery company?)

So far from what I know Apple has acquired around 21 companies. None of them being related to a battery manufacturing company. What I need to know is, has Apple ever acquired a battery manufacturing company? If not are there any rumours suggesting that they might in the near future?
With iCloud coming this fall, they must be looking ways of improving their products battery life. Any help or suggestions would be greatly appreciated!

Thanks guys.

Jason.

To anyone that may be interested, here are the list of the companies that Apple has acquired so far.

March 2, 1988\tNetwork Innovations\tSoftware\t United States\t—\t[7]
June 7, 1988\tOrion Network Systems\tSatellite communication systems\t United States\t—\t[8]
June 27, 1988\tStyleware\tComputer software\t United States\t—\t[9]
July 11, 1988\tNashoba Systems\tComputer software\t United States\t—\t[10]
January 3, 1989\tCoral Software\tComputer software\t United States\t—\t[11]
February 7, 1997\tNeXT\tComputer programming services\t United States\tUS$404,000,000\t[12]
September 2, 1997\tPower Computing-Clone-Making[note 1]\tClone computers\t United States\tUS$100,000,000\t[13]
January 8, 1999\tXemplar Education\tSoftware\t United Kingdom\tUS$4,926,000\t[14]
November 3, 1999\tRaycer Graphics\tComputer graphic chips\t United States\tUS$15,000,000\t[15]
January 7, 2000\tNetSelector\tInternet software\t United States\t—\t[16]
April 11, 2000\tAstarte-DVD Authoring Software[note 2]\tSoftware\t Germany\t—\t[17]
May 11, 2001\tbluebuzz\tInternet service provider\t United States\t—\t[18]
July 9, 2001\tSpruce Technologies[note 3]\tGraphics software\t United States\t—\t[19]
December 31, 2001\tPowerSchool\tOnline info systems services\t United States\tUS$62,000,000\t[20]
February 1, 2002\tNothing Real\tSpecial effects software\t United States\tUS$15,000,000\t[21]
April 4, 2002\tZayante\tSoftware\t United States\tUS$13,000,000\t[22]
June 11, 2002\tSilicon Grail Corp-Chalice[note 4]\tDigital effects software\t United States\t—\t[23]
June 20, 2002\tPropel Software\tSoftware\t United States\t—\t[24]
July 1, 2002\tEmagic\tMusic production software\t Germany\tUS$30,000,000\t[25]
March 2005\tSchemasoft\tSoftware\t Canada\t—\t[26]
April 2005\tFingerWorks\tGesture recognition company\t United States\t—\t[27][28]
October 16, 2006\tSilicon Color\tSoftware\t United States\t—\t[29]
December 4, 2006\tProximity\tSoftware\t Australia\t—\t[30]
April 24, 2008\tP.A. Semi\tSemiconductors\t United States\tUS$278,000,000\t[31]
July 7, 2009\tPlacebase\tMaps\t United States\t—\t[32]
December 6, 2009\tLala.com\tMusic streaming\t United States\tUS$17,000,000\t[33]
January 5, 2010\tQuattro Wireless\tMobile advertising\t United States\tUS$275,000,000\t[34]
April 27, 2010\tIntrinsity\tSemiconductors\t United States\tUS$121,000,000\t[35]
April 27, 2010\tSiri\tSoftware\t United States\t—\t[36]
July 14, 2010\tPoly9\tWeb-based mapping\t Canada\t—\t[37]