Patent ID: 7511874

Claim:
Electrochromic cell switchably connected to a battery ( 7 ) between first ( 8 ) and second ( 9 ) terminals to create a potential difference therebetween, said electrochromic cell comprising: a first layer ( 4 ) of inorganic, transparent electrochromic material; and a second layer ( 3 ) of inorganic, transparent electrolyte having cations and defined light absorption characteristics such that said cations migrate from said second layer to said first layer when the potential difference is applied across said electrochromic cell to modify said defined light absorption characteristics and said cations migrate from said first layer to said second layer when the potential difference is removed from said electrochromic cell returning said second layer ( 3 ) to its defined light absorption characteristics wherein said cations are Na + cations and said second layer ( 3 ) includes at least one compound defined by the of general formula: Na 1+x Zr 2 Si x P 3âˆ’x O 12 in which x is chosen to respond to the following conditions: 1.6â‰¦xâ‰¦2.4.