Parallel Battery Assembly for Self-Discharge Protection
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Solution Overview
Problem
All-solid lithium ion batteries face self-discharge issues leading to irreversible damage when not recharged for extended periods, which existing solutions fail to adequately address without modifying the load or recharge source.
Innovation Solution
An assembly of two all-solid thin-film lithium ion batteries with different electrochemical structures and voltage ranges, where a secondary battery with a smaller capacity and specific materials delays the critical discharge threshold of the primary battery by operating in parallel and disconnecting from the load when voltage reaches a certain threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single all-solid lithium ion battery is used, then the battery structure is simple, but the battery suffers irreversible damage during extended chargeless periods due to self-discharge
Solution Approach 1:
The battery system is segmented into two distinct batteries: a first all-solid lithium ion battery for normal operation and a second all-solid lithium ion battery specifically designed to protect against extended chargeless periods. Each battery has optimized electrochemical structures suited to its function, with the second battery having a lower voltage range tailored for protection mode operation.
Solution Approach 2:
The second battery acts as an intermediary protective element between the load and the first battery. When the first battery voltage drops below the threshold, the second battery activates to maintain the voltage within safe ranges, preventing irreversible damage to the first battery during extended periods without recharging.
2Reliability
If a second battery is added to protect against self-discharge damage, then the protection capability is improved, but the battery assembly complexity increases
Solution Approach 1:
Both batteries are electrically connected in parallel, merging their protective functions into a single integrated assembly. The control circuit manages both batteries through unified voltage monitoring and threshold comparison, coordinating their operation as a combined protection system rather than separate independent systems.
Solution Approach 2:
The second battery serves multiple functions: it acts as a voltage buffer during normal operation, activates as a protective source when the first battery voltage drops below the threshold, and maintains the overall voltage within safe ranges during extended chargeless periods. This multi-functionality reduces the need for additional dedicated protection components.
3Reliability
If the second battery operates with a lower voltage range, then the protection against over-discharge is improved, but the available capacity for power delivery is reduced
Solution Approach 1:
Each battery is designed with electrochemical structures optimized for its specific functional role. The first battery uses materials optimized for high voltage operation and power delivery, while the second battery uses materials optimized for lower voltage operation and protection functions. This local optimization ensures each battery performs its designated function efficiently without compromise.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively extends the lifetime of the primary battery by compensating for leakage currents and preventing irreversible damage during extended non-recharge periods without increasing battery size or complexity.
Implementation Method 1
a self-discharge phenomenon which, if lasting too long, damages the battery, occurs at the internal structure level of the battery
Data Source
AI summary
An assembly of batteries includes a first battery and a second battery electrically connected in parallel. The first battery is configured to deliver a battery capacity in a first power supply voltage range. The second battery is configured to deliver a battery capacity in a second voltage range. An upper limit of the second voltage range is set between upper and lower limits of the first voltage range. In an operating system, if supplied battery power falls below a threshold, the parallel connected first and second batteries are disconnected from the load.