Disclosed are a lithium transition metal oxide and a lithium secondary battery, in which a ratio of average particle diameter D50 of the lithium transition metal oxide to average particle diameter D50 of a transition metal precursor for preparation of the lithium transition metal oxide satisfies the condition represented by Equation 3 below:

[00001]$\begin{array}{cc}0<\frac{\begin{array}{c}\mathrm{Average}\mathrm{particle}\mathrm{diameter}D50\mathrm{of}\mathrm{lithium}\mathrm{transition}\\ \mathrm{metal}\mathrm{oxide}\end{array}}{\begin{array}{c}\mathrm{Average}\mathrm{particle}\mathrm{diameter}D50\mathrm{of}\mathrm{transition}\mathrm{metal}\\ \mathrm{precursor}\end{array}}<1.2.& \left(3\right)\end{array}$

Disclosed are a lithium transition metal oxide and a lithium secondary battery, in which a ratio of average particle diameter D50 of the lithium transition metal oxide to average particle diameter D50 of a transition metal precursor for preparation of the lithium transition metal oxide satisfies the condition represented by Equation 3 below:

[00001]$\begin{array}{cc}0<\frac{\begin{array}{c}\mathrm{Average}\mathrm{particle}\mathrm{diameter}D50\mathrm{of}\mathrm{lithium}\mathrm{transition}\\ \mathrm{metal}\mathrm{oxide}\end{array}}{\begin{array}{c}\mathrm{Average}\mathrm{particle}\mathrm{diameter}D50\mathrm{of}\mathrm{transition}\mathrm{metal}\\ \mathrm{precursor}\end{array}}<1.2.& \left(3\right)\end{array}$

Provided are a positive electrode active material with which a nonaqueous electrolyte secondary battery having a high energy density can be obtained, a nickel-manganese composite hydroxide suitable as a precursor of the positive electrode active material, and production methods capable of easily producing these in an industrial scale. Provided is a nickel-manganese composite hydroxide represented by General Formula (1): Ni.sub.xMn.sub.yM.sub.z(OH).sub.2+α and containing a secondary particle formed of a plurality of flocculated primary particles. The nickel-manganese composite hydroxide has a half width of a diffraction peak of a (001) plane obtained by X-ray diffraction measurement of at least 0.10° and up to 0.40° and has a degree of sparsity/density represented by [(void area within secondary particle/cross section of secondary particle)×100](%) of at least 0.5% and up to 10%. Also provided is a production method of the nickel-manganese composite hydroxide.

Provided are a positive electrode active material with which a nonaqueous electrolyte secondary battery having a high energy density can be obtained, a nickel-manganese composite hydroxide suitable as a precursor of the positive electrode active material, and production methods capable of easily producing these in an industrial scale. Provided is a nickel-manganese composite hydroxide represented by General Formula (1): Ni.sub.xMn.sub.yM.sub.z(OH).sub.2+α and containing a secondary particle formed of a plurality of flocculated primary particles. The nickel-manganese composite hydroxide has a half width of a diffraction peak of a (001) plane obtained by X-ray diffraction measurement of at least 0.10° and up to 0.40° and has a degree of sparsity/density represented by [(void area within secondary particle/cross section of secondary particle)×100](%) of at least 0.5% and up to 10%. Also provided is a production method of the nickel-manganese composite hydroxide.

Disclosed are actuators containing an active layer comprising at least one metal hydroxide, the active layer having a first volume under no stimulation and a second volume either greater than or smaller than the first volume under stimulation; and a passive layer comprising a porous polymer membrane, the passive layer having an elastic modulus at least half of an elastic modulus of the active layer.

Disclosed are actuators containing an active layer comprising at least one metal hydroxide, the active layer having a first volume under no stimulation and a second volume either greater than or smaller than the first volume under stimulation; and a passive layer comprising a porous polymer membrane, the passive layer having an elastic modulus at least half of an elastic modulus of the active layer.

There is provided a cathode active material precursor for a non-aqueous electrolyte secondary battery that is a complex metal hydroxide with a flow factor of 10 or greater to 20 or smaller.

A positive electrode active material including a nickel-containing lithium transition metal oxide containing nickel in an amount of 60 mol % or more based on a total number of moles of transition metals excluding lithium, and a coating layer which is formed on a surface of the nickel-containing lithium transition metal oxide and includes a lithium-containing inorganic compound, a nickel oxide, and a nickel oxyhydroxide is provided. A method of preparing the positive electrode active material, and a positive electrode for a lithium secondary battery and a lithium secondary battery which include the positive electrode active material are also provided.

A method of preparing a positive electrode active material includes mixing a lithium raw material with a high nickel-containing transition metal hydroxide containing nickel in an amount of 60 mol % or more based on a total number of moles of the transition metal hydroxide and sintering the mixture to prepare a positive electrode active material, wherein the sintering includes a sintering step of heat-treating at 700° C. to 900° C. for 8 hours to 12 hours, a cooling step of cooling to room temperature, and an aging step of having a holding time when a temperature reaches a specific point during the cooling step. A positive electrode active material which is prepared by the method and has a reduced moisture content, and a positive electrode for a lithium secondary battery and a lithium secondary battery which include the positive electrode active material are also provided.

A method of preparing a positive electrode active material includes mixing a lithium raw material with a high nickel-containing transition metal hydroxide containing nickel in an amount of 60 mol % or more based on a total number of moles of the transition metal hydroxide and sintering the mixture to prepare a positive electrode active material, wherein the sintering includes a sintering step of heat-treating at 700° C. to 900° C. for 8 hours to 12 hours, a cooling step of cooling to room temperature, and an aging step of having a holding time when a temperature reaches a specific point during the cooling step. A positive electrode active material which is prepared by the method and has a reduced moisture content, and a positive electrode for a lithium secondary battery and a lithium secondary battery which include the positive electrode active material are also provided.