Layered oxides LiNi
x
Co
y
Mn
z
O2 are
widely used as the main cathode material for high-energy lithium-ion
batteries. Over long-term cycling, irreversible phase transformations
in layered oxides usually occur along with the loss of active lithium,
which directly reflects in the sharp decrease of capacity. However,
it is difficult to accurately and rapidly determine lithium content
in aged materials, raising extreme impediments in the direct recycling
of layered oxides. Herein, we propose a facile method for quick and
accurate calculation of the residual lithium content through the developed
relationship of shear strain and the states of charge. Based on this
recognization, a discharge capacity close to the original capacity
of the pristine material is achieved in the regenerated material by
combining a hydrothermal method with annealing treatment. The recycled
material demonstrates a dramatic improvement in electrochemical properties,
especially the high rate performance. This method not only effectively
realizes the quantitative regeneration of cathode materials but also
provides a possible strategy for the future development of direct
regeneration.