An electrochemical cell comprises an anode, a cathode and an electrolyte composition, wherein the anode comprises as anode active material a combination of at least a carbon material and a silicon material; and the electrolyte composition comprises a solvent, from 0.5 wt. % to 70 wt. %, based on the total weight of the electrolyte, of a fluorinated acyclic carboxylic acid ester compound, from 0.5 wt. % 10 wt. %, based on the total weight of the electrolyte, of a fluorinated cyclic carbonate compound; and an electrolyte salt.

A positive electrode (100) includes a positive electrode current collector (110), a positive electrode mixture (120), and a mixture (130). The positive electrode current collector (110) has a first surface (112). The first surface (112) of the positive electrode current collector (110) includes a first region (112a), a second region (112b), and a third region (112c). The positive electrode (100) satisfies the following expression (1).

0≤L3/(L1+L3)≤0.075  (1)

Here, L1 is a length of the positive electrode (100) of the first region (112a) of the positive electrode (100) in one direction (first direction (X)), and L3 is a length of the third region (112c) of the positive electrode (100) in the one direction (first direction (X)).

A positive-electrode active material contains a compound that has a crystal structure belonging to a space group FM3-M and contains is represented by the composition formula (1) and an insulating compound,
Li.sub.xMe.sub.yO.sub.αF.sub.β  (1)
wherein Me denotes one or two or more elements selected from the group consisting of Mn, Co, Ni, Fe, Al, B, Ce, Si, Zr, Nb, Pr, Ti, W, Ge, Mo, Sn, Bi, Cu, Mg, Ca, Ba, Sr, Y, Zn, Ga, Er, La, Sm, Yb, V, and Cr, and the following conditions are satisfied.
1.7≤x≤2.2
0.8≤y≤1.3
1≤α≤2.5
0.5≤β≤2

A porous silicon composite including: a porous silicon composite cluster comprising a porous silicon composite secondary particle and a second carbon flake on at least one surface of the porous silicon composite secondary particle; and a carbonaceous layer on the porous silicon composite cluster, the carbonaceous layer comprising amorphous carbon, wherein the porous silicon composite secondary particle comprises an aggregate of two or more silicon primary particles, the two or more silicon primary particles comprise silicon, a silicon suboxide of the formula SiO.sub.x, wherein 0<x<2 on a surface of the silicon, and a first carbon flake on at least one surface of the silicon suboxide, the silicon suboxide is in a form of a film, a matrix, or a combination thereof, and the first carbon flake and the second carbon flake are each independently present in a form of a film, particles, a matrix, or a combination thereof. Also a method of preparing the porous silicon composite, a carbon composite, an electrode, and a device, each including the porous silicon composite, and a lithium battery including the electrode.

A sacrificial positive active material for a lithium-ion electrochemical element which is a compound of formula (Li.sub.2O).sub.x (MnO.sub.2).sub.y(MnO).sub.z(MO.sub.a).sub.t in which: x+y+z+t=1; 1−x−y≥0; 0.97≥x≥0.6; y≤0.45; x −0.17; y≥0; y+z>0; t≥0; 1≤a<3. M is selected from the group consisting of Fe, Co, Ni, B, Al, Ti, Si, V, Mo, Zr and a mixture thereof.

A negative electrode for a rechargeable lithium and a rechargeable lithium battery, and the negative electrode includes a current collector and a negative active material layer positioned on the current collector, wherein the negative active material layer includes a plurality of holes at a hole density of about 90 pt/mm.sup.2 or more.

An electrochemical cell comprises an anode, a cathode and an electrolyte composition, wherein the anode comprises as anode active material a combination of at least a carbon material and a silicon material; and the electrolyte composition comprises a solvent, from 0.5 wt. % to 70 wt. %, based on the total weight of the electrolyte, of a fluorinated acyclic carbonate compound, from 0.5 wt. % to 10 wt. %, based on the total weight of the electrolyte, of a fluorinated cyclic carbonate compound; and an electrolyte salt.

Particulate electrode active material with an average particle diameter in the range of from 2 to 20 μm (D50) having a general formula Li.sub.1+xTM.sub.1−xO.sub.2 wherein TM is a combination of Ni, Co and Al, and, optionally, at least one more metal selected from Mg, Ti, Zr, Nb, Ta, Mo, Mn, and W, with at least 80 mole-% of TM being Ni, and wherein x is in the range of from zero to 0.2, wherein the Co content at the outer surface of the secondary particles is higher than at the center of the secondary particles by a factor of at most 5 or by at most 30 mol-%, referring to TM.

Porous carbon particles, and a positive electrode active material and a lithium secondary battery including the same. This may improve the energy density of the lithium secondary battery by applying a porous electrode containing micropores and mesopores and having a uniform size distribution and shape as a positive electrode material.

The invention provides filamentous organism-derived carbonaceous materials doped with organic and/or inorganic compounds, and methods of making the same. In certain embodiments, these carbonaceous materials are used as electrodes in solid state batteries and/or lithium-ion batteries. In another aspect, these carbonaceous materials are used as a catalyst, catalyst support, adsorbent, filter and/or other carbon-based material or adsorbent. In yet another aspect, the invention provides battery devices incorporating the carbonaceous electrode materials.