Abstract: A measurement system may include a diffusive cavity including a reflective internal surface and one or more ports, a sample chamber located within the diffusive cavity, and a light source to direct measurement light into the diffusive cavity through one of the one or more ports of the diffusive cavity. The diffusive cavity may uniform illumination of the sample through diffusive reflection of at least one of the measurement light from the light source or scattered measurement light from the sample. The system may further include two or more detectors to capture light exiting at least one of the one or more ports. The system may further include a controller to receive detection signals from the two or more detectors indicative of the scattering of the measurement light by the sample and determine one or more time-varying properties of the sample based on the detection signals.

Abstract: An electrochemical apparatus includes an electrode assembly, where the electrode assembly includes a positive electrode plate, a negative electrode plate, and a separator for separating the positive electrode plate and the negative electrode plate. The positive electrode plate includes a positive electrode current collector, a positive electrode active material layer, and a non-active material layer. The positive electrode active material layer is formed on a surface of the positive electrode current collector, and the non-active material layer is formed on a surface of the positive electrode active material layer away from the positive electrode current collector. In a first direction, the non-active material layer has a thickness of 1 µm to 20 µm, where the first direction is a thickness direction of the positive electrode current collector. A diffusion rate of lithium ions in the non-active material layer is less than that in the positive active material layer.

Abstract: An electrochemical device includes a positive electrode plate which includes a positive active material layer and a negative electrode plate which includes a negative current collector, a first negative active material layer, and a second negative active material layer. In a length direction, the first negative active material layer includes a first edge and a second edge opposite to the first edge. In the length direction, the second negative active material layer includes a third edge and a fourth edge opposite to the third edge. In the length direction, the positive active material layer includes a fifth edge and a sixth edge opposite to the fifth edge. The third edge protrudes beyond the first edge and the fifth edge in the length direction. A distance between the first edge and the fifth edge in the length direction of the negative electrode plate is less than 2 mm.