Abstract: The present invention relates to a data collection system and a data collection method in a sensor network, enabling sensor modules to consume lower amounts of power. The base station transmits data collection request signals to one or more sensor modules which are lower than the base station by 1 in a tree structure. Each sensor module which has received the data collection request signal transfers the signal to one or more sensor modules which are lower than the module by 1. The base station regards the transfer of the signal as ACK for the data collection request signal transmitted therefrom to the sensor module which is lower than the base station by 1. The transmission of a data collection acknowledgement signal starts from a sensor module at the low-order end. When a sensor module receives the data collection acknowledgement signal from a downstream sensor module which is lower than the module by 1, the module transmits the signal to an upstream sensor module which is higher than the module by 1.

Abstract: A cathode active material for a lithium-ion secondary battery includes a spinel lithium manganese composite oxide expressed by the general formula: Lia(NixMn2−x−q−rQqRr)O4, wherein 0.4≦x≦0.6, 0<q, 0≦r, x+q+r<2, 0<a<1.2, Q is at least one element selected from the group consisting of Na, K and Ca, and R is at least one element selected from the group consisting of Li, Be, B, Mg and Al.

Abstract: A cathode active material for a secondary battery including a lithium-manganese composite oxide having a spinel structure and represented by the following general formula (I), Lia(MxMn2-x-y-zYyAz)(O4-wZw) (I), wherein 0.5≦x≦1.2, 0≦y, 0≦z, x+y+z<2, 0≦a≦1.2 and 0≦w≦1; M contains at least Co and may further contains at least one element selected from the group consisting of Ni, Fe, Cr and Cu; Y is at least one element selected lo from the group consisting of Li, Be, B, Na, Mg, Al, K and Ca; A is at least one of Ti and Si; and Z is at least one of F and Cl. When the cathode active material for the secondary battery is used as the cathode for the a secondary battery, a higher operating can be realized while suppressing the reliability reduction such as the capacity decrease after the cycles and the deterioration of the crystalline structure at a higher temperature.