Analysis of Causes of Heat Loss of Lithium Ion Battery Positive Materials

　　Author ：Iflowpower – Portable Power Station Supplier

The electric vehicle represented by Tesra is used to use NCA, NCM811 or NCM622 high nickel-based material as a lithium ion battery positive material. However, this high-nickel layer-shaped positive electrode material has safety problems, Canadian light source energy storage group Dr. Zhou Wei, Dr.

Wang Jian, Wang Jian, a Chemical Imaging Line Station and deputy professor of Xiamen University of Science and Technology, for the first time, the phase distribution of complex composite electrode heat until the complex composite electrode heat out of control, and multi-phase separation phenomenon before and after heat loss. Relevance is visualized by nano-level, and it is found that thermal out of control may be closely correlated with the distribution of conductors and binders. The lithium ion battery represented by NCA, NCM811 or NCM622 has the advantages of high capacity, low cost, and environmental hazards.

At present, the electric vehicle represented by Tesla is used. However, there is a problem in the presence of safety of high nickel layered positive electrodes, especially at high temperature lower material decomposition, release oxygen, causes thermal out of control, resulting in battery combustion explosion. From the perspective of basic theory, in-depth understanding of the phase separation of solid state electrodes under thermal out-of control is important to fundamentally solve the stability defects of this material intrinsic.

From the perspective of practical analysis, the behavior of the study phase is separated in the actual porous composite electrode, and corresponds to the size effect of the positive electrode material, the correlation between crystal surface regulation, and surface passivation film, is the basis research and actual application phase. Combined ideal method. However, this idea must have advanced characterization means to be realized.

Dr. Zhou Wei, the Canadian Light Source Storage Group, and Dr. Wang Jian in the Chemical Imaging Line station works closely with the deputy professor of the road secretary of Xiamen University of Technology to innovate the transmission X-ray scanning of elements and orbit selectivity, chemical and electronic structures.

MicroT (PEEM) is used to study the behavior of phase separation of thermostatic acid lithium lithium laminate particles in the porous electrode. This work is reported as a research highlight in the form of the ChemicalCommunications. Through the in situ student, the authors used the phase distribution of the complex composite electrode heat until the complex composite electrode thermal out of control, and the correlation of the various phase separation phenomena in the correlation before and after thermal out-of-control was visualized.

Visualization. The heat loss before and after the phase separation in a single electrode particle level exhibits unpredictable unevenness. This non-uniformization and particle size, crystal surface structure is not obvious, but the distribution of conductive agents and binders is closely correlated.

This is the first time to achieve nano visualization separated by the same particles before and after the heat loss, and associate it with its electrode environment. This means of further deepening the thermal displacement behavior of the laminated material is significant, suitable for promoting the reactive mechanism, attenuation mechanism of other electrode systems to study the thermal out of control. The article first uses the elemental sensitivity of the elements of PEEM with respect to the electrode component, including lithium cobaltate, PVDF, and distribution of electrically conductive carbon black.

Before the heat loss, the conductive agent and the binder are mixed uniformly coexist, but this agglomeration is uneven in the surface of the lithium cobaltate particles and the particles. The thermal loss of the PVDF is obvious, while the conductive carbon black is still uniformly distributed in lithium cobalt acid in the form of agglomeration. PEEM can reach a spatial resolution of 100 nm, and can be imaged on 50 um electrode surface.

High spatial resolution and high-imaging interval achieve high resolution imaging of multi-particles. The morphology of lithium cobaltate particles can be used to study the thermal displacement behavior of the same electrode particles before and after thermostat. The latest discovery of conductive agents, the distribution of the binder may result in a lithium-ion battery positive material thermal out-of-control diagram 1.

The elemental distribution and correlation and correlation diagram of after thermostat (A, B) (C, D) are separated into each The absorption spectrum of the cobalt element of the pixel unit cobalt element uses a single phase, including the spectral decomposition fitting of CO2 + (thermal out-controlled release oxygen formation), CO3 + (LCO) or CO3.5 + (normal full charge LCO). Highly unevenness of phase separation is well reflected in Figures C and D.

If the phase separation map is obtained with the resulting element profile, this phase separation has great correlation with the distribution of the conductive carbon black before and after thermal loss. The thermostat has significantly reduced the size of the phase separation. It is different from the conclusions obtained by chemical charging after chemical charging by chemical charging in the past.

The effects of electrode particles, size, and crystal surface orientation are far less than particulate environment, especially the effect of conductive agent.