POSITIVE ELECTRODE ACTIVE MATERIAL FOR LITHIUM SECONDARY BATTERY, METHOD FOR MANUFACTURING THE SAME, LITHIUM SECONDARY BATTERY ELECTRODE, AND LITHIUM SECONDARY BATTERY

PROBLEM TO BE SOLVED: To increase the initial efficiency of a lithium secondary battery.SOLUTION: A positive electrode active material for a lithium secondary battery comprises particles of a lithium transition metal composite oxide. The lithium transition metal composite oxide particles have an α-NaFeOtype structure, and include Ni, Co and Mn as a transition metal (Me), in which the mole ratio Ni/Me of Ni to Me is given by Ni/Me≥0.4. The lithium transition metal composite oxide particles have two or more peaks in a particle size distribution, and have at least one peak on a particle diameter side larger than a diameter showing a maximum peak. A method for manufacturing the positive electrode active material for a lithium secondary battery comprises the steps of: mixing particles of a precursor of the transition metal compound including Ni, Co and Mn with a lithium compound, and a fluorine source including fluorine of 2.5 mol% or more to the precursor; and baking the resultant mixture at a temperature over 950°C, thereby manufacturing the lithium transition metal composite oxide particles.SELECTED DRAWING: Figure 1 【課題】リチウム二次電池の初期効率を向上させる。【解決手段】リチウム遷移金属複合酸化物粒子を含有するリチウム二次電池用正極活物質であって、前記リチウム遷移金属複合酸化物粒子は、α−ＮａＦｅＯ２型構造を有し、遷移金属（Ｍｅ）としてＮｉ、Ｃｏ及びＭｎを含み、Ｍｅに対するＮｉのモル比Ｎｉ／ＭｅがＮｉ／Ｍｅ≧０．４であり、粒度分布において２つ以上のピークを有するとともに、最大ピークを示す粒径よりも大粒径側に少なくとも１つのピークを有する、リチウム二次電池用正極活物質である。また、Ｎｉ、Ｃｏ及びＭｎを含む遷移金属化合物の前駆体粒子に、リチウム化合物と、前記前駆体に対して２．５ｍｏｌ％以上のフッ素を含むフッ素源とを混合し、９５０℃を超える温度で焼成して、前記リチウム遷移金属複合酸化物粒子を製造する、前記リチウム二次電池用正極活物質の製造方法である。【選択図】図１