Liquid electrolyte containing a flammable organic solvent is used for a presently commercialized lithium battery, so that a safety device for restraining temperature rise during a short circuit is necessary therefor. In contrast, an all solid lithium battery in which the liquid electrolyte is replaced with a solid electrolyte layer may intend the simplification of the safety device by reason of not using the organic solvent.
Various studies have been made in the field of the all solid lithium battery. For example, in Patent Literature 1, a cathode membrane for an all solid lithium secondary battery containing lithium ion conductive material particles including sulfur, phosphorus and lithium, in which a membrane thickness is 10 to 300 μm and a voidage is 30% or less, is disclosed. In addition, compressing at a pressure of 30 MPa or more is disclosed as a manufacturing method of the cathode membrane.
On the other hand, with regard to a technique on a lithium secondary battery using liquid electrolyte, in Patent Literature 2, active material particles having a shell part composed of a lithium transition metal oxide, a hollow part formed inside the shell part, and a through-hole for piercing through the shell part are disclosed. Similarly, in Patent Literature 3, a storage element using an active material as secondary particles formed so that plural primary particles assemble to have a hollow area inside is disclosed.