Large-volume-change lithium battery electrodes

A battery electrode material, comprising:

• primary particles formed of Si;
• and
• a secondary particle defining multiple, closed internal volumes,
• wherein the secondary particle consists of a homogeneous amorphous composition,
• wherein a number of the closed internal volumes is at least 100,
• wherein the primary particles are disposed within the closed internal volumes bounded by the homogeneous amorphous composition of the secondary particle,
• wherein a single primary particle is disposed within each closed internal volume,
• wherein, for at least one cycling state of Si, at least one primary particle occupies less than 100% of a respective closed internal volume to define a void space, such that a ratio of a volume of the void space relative to a volume of the primary particle inside the closed internal volume is between 1:2 and 2.9:1, and the void space is devoid of carbon.