Positive electrode, secondary battery, battery pack, and vehicle

Abstract

According to one embodiment, a positive electrode includes positive electrode active material particles, polymer fibers and inorganic solid particles. The polymer fibers have an average fiber diameter of 1 nm to 100 nm.

1 . A positive electrode comprising a positive electrode active material-containing layer that contains positive electrode active material particles,
 polymer fibers having an average fiber diameter of 1 nm to 100 nm, and   inorganic solid particles.   
     
     
         2 . The positive electrode of  claim 1 , wherein the polymer fibers include cellulose fibers. 
     
     
         3 . The positive electrode of  claim 1 , wherein the inorganic solid particles include at least one material selected from the group consisting of Al 2 O 3 , TiO 2 , ZrO 2 , and a phosphate compound. 
     
     
         4 . The positive electrode of  claim 3 , wherein the phosphate compound has a NASICON structure and is expressed as Li 1+y Al x M 2−x (PO 4 ) 3  (M represents at least one element selected from the group consisting of Ti, Ge, Sr, Sn, Zr, and Ca for 0≤x≤1 and 0≤y≤1). 
     
     
         5 . The positive electrode of  claim 1 , wherein a content of the polymer fibers in the positive electrode active material-containing layer ranges from 0.2 wt % to 5 wt %, and a content of the inorganic solid particles in the positive electrode active material-containing layer ranges from 0.5 wt % to 10 wt %. 
     
     
         6 . The positive electrode of  claim 1 , wherein the positive electrode active material particles comprise at least one material selected from the group consisting of a lithium manganese composite oxide, a lithium cobalt composite oxide, a lithium nickel composite oxide, a lithium nickel cobalt composite oxide, a lithium cobalt aluminum composite oxide, a lithium nickel aluminum composite oxide, a lithium manganese nickel composite oxide having a spinel structure, a lithium manganese cobalt composite oxide, a lithium-containing phosphate compound having an olivine structure, a fluorinated iron sulfate, and a lithium nickel cobalt manganese composite oxide. 
     
     
         7 . The positive electrode of  claim 1 , wherein the positive electrode active material particles comprise Li x Ni 1−y−z CO y Mn z O 2 , where 0<x≤1.1, 0<y≤0.5, 0<z≤0.5, 0<1−y−z<1. 
     
     
         8 . A secondary battery comprising:
 the positive electrode according to  claim 1 ;   a negative electrode; and   an electrolyte.   
     
     
         9 . The secondary battery of  claim 8 , wherein the negative electrode includes a titanium-containing oxide. 
     
     
         10 . The secondary battery of  claim 9 , wherein the titanium-containing oxide includes at least one material selected from the group consisting of a lithium titanium oxide having a spinel structure, a monoclinic titanium oxide, and a niobium titanium oxide. 
     
     
         11 . A battery pack comprising the secondary battery according to  claim 8 . 
     
     
         12 . The battery pack of  claim 11 , further comprising:
 an external power distribution terminal; and   a protective circuit.   
     
     
         13 . The battery pack of  claim 11 , which comprises plural of the secondary battery, and the secondary batteries are electrically connected in series, in parallel, or in a combination of series connection and parallel connection. 
     
     
         14 . A vehicle comprising the battery pack according to  claim 11 . 
     
     
         15 . The vehicle of  claim 14 , further comprising a mechanism configured to convert kinetic energy of the vehicle into regenerative energy.