In the failure analysis laboratory of energy accumulation new energy, a PN20160715001 numbered battery pack is being slowly dismantled. It was born in 2016 and retired last month after ten years of loading and service, with a cumulative cycle of more than 5,000 times. This is not an ordinary retired battery, but a "living file"-it records the design decisions, material selection and technological level of the previous generation of products, and it is also today ten years later, the most objective technical evaluation is given.

Box disassembly: the physical mark of ten years of wind and frost. The protective coating on the surface of the box appears partial pulverization and slight corrosion, but the overall structure is complete without deformation and crack. The aging of the sealing ring is obvious, and the elastic modulus decreases by about 40% compared with the new product, which explains the slight leakage in the later air tightness test. This discovery directly promoted the current double protection upgrade of "anodic oxidation + fluorocarbon coating", and the weatherproof life goal was raised to 20 years.

Cell dismantling: the design in the aging portrait echoes. The average capacity retention rate of cell at the edge of the module is 75%, while that at the center is 81%. The 3% difference points to the "edge effect" of the thermal management design in that year-the heat dissipation condition of the center cell is better than that of the edge, and the aging rate is differentiated after long-term operation. This discovery directly promoted the development of liquid cooling design of the current "bionic flow channel", aiming to compress the temperature difference of the whole package from 8℃ of that year to within 3℃.

BMS backtracking: the "time capsule" in the data ". Historical data show that in the first three years, it operated at a relatively mild 1C rate, and the attenuation was gentle; In the fourth year, the operation strategy was adjusted, and it frequently participated in 2C fast charge, and the attenuation slope became steeper. This data provides empirical support for the current "elastic SOC window" and "segmented fast charge" algorithms-achieving dynamic balance between income and life span.

material aging: ten years of changes in the micro world. Under scanning electron microscope, SEI film thickness on the surface of lithium iron phosphate particles increased from several nanometers to about 50 nanometers, and microcracks appeared on the edge of some particles; trace of lithium deposition is detected in the local area of negative graphite-"evidence" that lithium ions are not completely embedded during low-temperature fast charging ". These microscopic findings have promoted the pre-research of advanced technologies such as "wide temperature range electrolyte" and "gradient coating.

Energy gathering new energy will be dismantled and retired battery it is called "technical archaeology"-not for nostalgia, but for digging the long-term echo of design decisions from the sedimentary layer of time. Every retired battery is a "living teaching material". It will not lie or cater to it. It will only use the capacity attenuation curve, internal resistance growth slope and material micro-morphology to give the most objective technical evaluation.

When the industry is driven by the pressure of short-term performance, juanneng new energy chooses to look back at those "veterans" regularly and listen to the voice of time. Because we know very well that the real technology leads, not standing on the top of the mountain laughing at people who are still climbing, but when others have not seen the mountain, they begin to measure its height.