  Despite the ever-increasing use across different sectors, the lithium-ion
batteries (LiBs) have continually seen serious concerns over their thermal
vulnerability. The LiB operation is associated with the heat generation and
buildup effect, which manifests itself more strongly, in the form of highly
uneven thermal distribution, for a LiB pack consisting of multiple cells. If
not well monitored and managed, the heating may accelerate aging and cause
unwanted side reactions. In extreme cases, it will even cause fires and
explosions, as evidenced by a series of well-publicized incidents in recent
years. To address this threat, this paper, for the first time, seeks to
reconstruct the three-dimensional temperature field of a LiB pack in real time.
The major challenge lies in how to acquire a high-fidelity reconstruction with
constrained computation time. In this study, a three-dimensional thermal model
is established first for a LiB pack configured in series. Although spatially
resolved, this model captures spatial thermal behavior with a combination of
high integrity and low complexity. Given the model, the standard Kalman filter
is then distributed to attain temperature field estimation at substantially
reduced computational complexity. The arithmetic operation analysis and
numerical simulation illustrate that the proposed distributed estimation
achieves a comparable accuracy as the centralized approach but with much less
computation. This work can potentially contribute to the safer operation of the
LiB packs in various systems dependent on LiB-based energy storage, potentially
widening the access of this technology to a broader range of engineering areas.
