Lithium Metal Battery Pack Endplate Control for Uniform Pressure
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Solution Overview
Problem
Lithium metal batteries face challenges with cell swelling and varying surface pressures between the beginning of life (BOL) and end of life (EOL), leading to accelerated degradation and potential short circuits.
Innovation Solution
A battery system configuration that includes a housing with stacked battery cells, an endplate with support bodies that adjust surface pressure, and a pressure sensor to detect swelling and adjust the surface pressure dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium metal battery uses lithium negative electrode instead of carbon material, then energy density is improved, but cell swelling and surface pressure variation occur
Solution Approach 1:
The endplate is designed to be movable along the stacking direction of battery cells, allowing it to dynamically adjust its position in response to cell swelling. This dynamic adjustment maintains uniform surface pressure on the cells throughout charging and discharging cycles, preventing the harmful effects of pressure variation while preserving the high energy density benefits of lithium metal batteries
Solution Approach 2:
A pressure sensor is integrated into the system to detect surface pressure conditions in real-time. The sensor provides feedback about the pressure state, which triggers automatic adjustment of the endplate position through the actuator. This closed-loop feedback mechanism ensures that surface pressure remains uniform despite cell swelling, resolving the contradiction between high energy density and structural stability
2Stability of the object's composition
If buffer pad is inserted in battery module, then cell swelling is accommodated, but surface pressure uniformity deteriorates
Solution Approach 1:
The invention removes the traditional buffer pad component from the battery module and replaces it with a movable endplate system. This extraction eliminates the pressure non-uniformity problem caused by buffer pads while still accommodating cell swelling through the endplate's positional adjustments, thereby maintaining both swelling accommodation and pressure uniformity
3Reliability
If surface pressure is increased to prevent short circuit, then reliability is improved, but cell degradation accelerates
Solution Approach 1:
The system dynamically changes the surface pressure parameter by adjusting the endplate position rather than maintaining a constantly high pressure. The pressure is modulated according to actual cell conditions detected by the pressure sensor, providing sufficient pressure to prevent short circuits while avoiding excessive pressure that would accelerate degradation, thus extending battery lifespan
Data Source
AI summary
A battery pack for a vehicle, and more particularly, to a battery system capable of implementing a uniform surface pressure of a lithium metal battery. The battery system includes a plurality of battery cells stacked in a housing, an endplate positioned at one end of the housing, and positioned on a cell disposed at a distal end among the plurality of battery cells, and the endplate being configured to provide a surface pressure toward the plurality of battery cells, a plurality of frames positioned at peripheries of the plurality of battery cells with respect to the plurality of battery cells, a plurality of support bodies connected to the endplate while penetrating the plurality of frames in a direction toward the plurality of battery cells, and a pressure sensor positioned on the endplate.